Retinitis Pigmentosa Stem Cell Treatment

Stem Cell Treatmtent for Retinitis Pigmentosa

 
stem cell treatment for retinitis pigmentosa

Stem Cell Treatment for Retinitis Pigmentosa

Retinitis Pigmentosa treatments using stem cells is now an option...

Retinitis pigmentosa is a group of genetic eye conditions that leads to incurable blindness. In the progression of symptoms for Retinitis pigmentosa, night blindness generally precedes tunnel vision by years or even decades. Many people with Retinitis pigmentosa do not become legally blind until their 40s or 50s and retain some sight all their lives. Others go completely blind from Retinitis pigmentosa, in some cases as early as childhood. Progression of Retinitis pigmentosa is different in each case.

Retinitis pigmentosa is a type of progressive retinal dystrophy, a group of inherited disorders in which abnormalities of the photoreceptors (rods and cones) or the retinal pigment epithelium of the retina lead to progressive visual loss. Affected individuals first experience defective dark adaptation or nyctalopia (night blindness), followed by reduction of the peripheral visual field (known as tunnel vision) and, sometimes, loss of central vision late in the course of the disease.

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Stem Cell Treatment for Retinitis Pigmentosa

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Related Articles GeneReviews® Book. 1993 Authors: Adam MP, Ardinger HH, Pagon RA, Wallace SE, Bean LJH, Stephens K, Amemiya A Abstract CLINICAL CHARACTERISTICS: Mitochondrial DNA (mtDNA)-associated Leigh syndrome and NARP (neurogenic muscle weakness, ataxia, and retinitis pigmentosa) are part of a continuum of progressive neurodegenerative disorders caused by abnormalities of mitochondrial energy generation. Leigh syndrome (or subacute necrotizing encephalomyelopathy) is characterized by onset of symptoms typically between ages three and 12 months, often following a viral infection. Decompensation (often with elevated lactate levels in blood and/or CSF) during an intercurrent illness is typically associated with psychomotor retardation or regression. Neurologic features include hypotonia, spasticity, movement disorders (including chorea), cerebellar ataxia, and peripheral neuropathy. Extraneurologic manifestations may include hypertrophic cardiomyopathy. About 50% of affected individuals die by age three years, most often as a result of respiratory or cardiac failure. NARP is characterized by proximal neurogenic muscle weakness with sensory neuropathy, ataxia, and pigmentary retinopathy. Onset of symptoms, particularly ataxia and learning difficulties, is often in early childhood. Individuals with NARP can be relatively stable for many years, but may suffer episodic deterioration, often in association with viral illnesses. DIAGNOSIS/TESTING: The diagnosis of mtDNA-associated Leigh syndrome is established clinically in a proband with progressive neurologic disease with motor and intellectual developmental delay, signs and symptoms of brain stem and/or basal ganglia disease, raised lactate concentration in blood and/or cerebrospinal fluid, and any one of the following: Characteristic features on brain imaging. Typical neuropathologic changes. Typical neuropathology in a similarly affected sib. Identification of a pathogenic variant in one of the 14 mitochondrial genes known to be involved in mtDNA-associated Leigh syndrome confirms the diagnosis. The diagnosis of NARP is established in a proband with suggestive clinical features and identification of a heteroplasmic pathogenic variant in one of the three mitochondrial genes known to be involved in NARP. MANAGEMENT: Treatment of manifestations: Supportive treatment includes use of sodium bicarbonate or sodium citrate for acute exacerbations of acidosis and antiepileptic drugs for seizures. Dystonia is treated with benzhexol, baclofen, tetrabenazine, and gabapentin alone or in combination, or by injections of botulinum toxin. Anticongestive therapy may be required for cardiomyopathy. Regular nutritional assessment of daily caloric intake and adequacy of diet and psychological support for the affected individual and family are essential. Surveillance: Neurologic, ophthalmologic, and cardiologic evaluations at regular intervals to monitor progression and appearance of new symptoms. Care is frequently coordinated by a biochemical geneticist in North America, and by a metabolic physician/pediatrician elsewhere in the world. Agents/circumstances to avoid: Sodium valproate and barbiturates, anesthesia, and dichloroacetate. GENETIC COUNSELING: Mitochondrial DNA-associated Leigh syndrome and NARP are transmitted by maternal inheritance. The father of a proband is not at risk of having the mtDNA pathogenic variant. The mother of a proband usually has the mtDNA pathogenic variant and may or may not have symptoms. In most cases, the mother has a much lower proportion of abnormal mtDNA than the proband and usually remains asymptomatic or develops only mild symptoms. Occasionally the mother has a substantial proportion of abnormal mtDNA and develops severe symptoms in adulthood. Offspring of males with a mtDNA pathogenic variant are not at risk; all offspring of females with a mtDNA pathogenic variant are at risk of inheriting the pathogenic variant. The risk to offspring of a female proband of developing symptoms depends on the tissue distribution and proportion of abnormal mtDNA. Prenatal diagnosis and preimplantation genetic diagnosis for couples at increased risk of having children with mtDNA-associated Leigh syndrome or NARP are possible by analysis of mtDNA extracted from non-cultured fetal cells or from single blastomeres, respectively. However, long-term outcome cannot be reliably predicted on the basis of molecular genetic test results. PMID: 20301352
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Related Articles Recent advances in treatment of retinitis pigmentosa. Curr Stem Cell Res Ther. 2015;10(3):258-65 Authors: He Y, Zhang Y, Su G Abstract Retinitis pigmentosa (RP) is a group of inherited retinal disorders characterized by the progressive photoreceptors and pigment epithelial cells dysfunction. It is the most common retinal degeneration, responsible for loss of vision of most people worldwide. Until now its exact pathogenesis and etiology are not clear. So far there is no approved therapy. New approaches for RP therapy include cell transplantation, gene therapy, cytokine therapy, nutrition therapy, and hyperbaric oxygen therapy. Such therapies for retinal degenerative diseases are limited in their efficacy. This paper reviews the relevant documents, especially recent researches, and reviews advances in the treatment of RP. PMID: 25345673 [PubMed - indexed for MEDLINE]
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Related Articles Proceedings: debilitating eye diseases. Stem Cells Transl Med. 2014 Dec;3(12):1393-7 Authors: Caras IW, Littman N, Abo A Abstract Debilitating eye diseases such as age-related macular degeneration and retinitis pigmentosa currently represent a large unmet medical need that could potentially be addressed by stem cell therapy. A number of novel stem cell-based cellular therapies are now under development to treat a variety of eye diseases. The approaches being taken by the California Institute for Regenerative Medicine, together with its grantees, are discussed. PMID: 25378652 [PubMed - indexed for MEDLINE]
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Related Articles Genetic background and light-dependent progression of photoreceptor cell degeneration in Prominin-1 knockout mice. Invest Ophthalmol Vis Sci. 2014 Nov 20;56(1):164-76 Authors: Dellett M, Sasai N, Nishide K, Becker S, Papadaki V, Limb GA, Moore AT, Kondo T, Ohnuma S Abstract PURPOSE: Mutations in the Prominin-1 (Prom1) gene are known to cause retinitis pigmentosa and Stargardt disease, both of which are associated with progressive photoreceptor cell death. There are no effective therapies for either disorder. The aim of this study was to investigate the mechanism of the retinal degeneration in Prom1-deficient mouse models. METHODS: We constructed Prom1 knockout mice with two distinct genetic backgrounds of C57BL/6 and C57BL/6xCBA/NSlc, and investigated the photoreceptor degeneration by means of histology and functional tests.. In addition, we examined the effect of light on the Prom1(-/-) retina by rearing the mice in the normal light/dark cycle and completely dark conditions. Finally, we investigated if the retinoic-acid derivative Fenretinide slowed the pace of retinal degeneration in these mouse models. RESULTS: The Prom1(-/-)-knockout mice with both backgrounds developed photoreceptor degeneration after eye opening, but the CB57/BL6-background mice developed photoreceptor cell degeneration much faster than the C57BL/6xCBA/NSlc mice, demonstrating genetic background dependency.. Interestingly, our histologic and functional examination showed that the photoreceptor cell degeneration of Prom1-knockout mice was light-dependent, and was almost completely inhibited when the mutant mice were kept in the dark. The Prom1-knockout retina showed strong downregulation of expression of the visual cycle components, Rdh12 and Abca4. Furthermore, administration of Fenretinide, which lowers the level of the toxic lipofuscin, slowed the degeneration of photoreceptor cells. CONCLUSIONS: These findings improve our understanding of the mechanism of cell death in Prominin-1-related disease and provide evidence that fenretinide may be worth studying in human disease. PMID: 25414197 [PubMed - indexed for MEDLINE]
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Related Articles Patient-specific induced pluripotent stem cells (iPSCs) for the study and treatment of retinal degenerative diseases. Prog Retin Eye Res. 2015 Jan;44:15-35 Authors: Wiley LA, Burnight ER, Songstad AE, Drack AV, Mullins RF, Stone EM, Tucker BA Abstract Vision is the sense that we use to navigate the world around us. Thus it is not surprising that blindness is one of people's most feared maladies. Heritable diseases of the retina, such as age-related macular degeneration and retinitis pigmentosa, are the leading cause of blindness in the developed world, collectively affecting as many as one-third of all people over the age of 75, to some degree. For decades, scientists have dreamed of preventing vision loss or of restoring the vision of patients affected with retinal degeneration through drug therapy, gene augmentation or a cell-based transplantation approach. In this review we will discuss the use of the induced pluripotent stem cell technology to model and develop various treatment modalities for the treatment of inherited retinal degenerative disease. We will focus on the use of iPSCs for interrogation of disease pathophysiology, analysis of drug and gene therapeutics and as a source of autologous cells for cell transplantation and replacement. PMID: 25448922 [PubMed - indexed for MEDLINE]
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Related Articles Intravitreal autologous bone marrow CD34+ cell therapy for ischemic and degenerative retinal disorders: preliminary phase 1 clinical trial findings. Invest Ophthalmol Vis Sci. 2014 Dec 09;56(1):81-9 Authors: Park SS, Bauer G, Abedi M, Pontow S, Panorgias A, Jonnal R, Zawadzki RJ, Werner JS, Nolta J Abstract PURPOSE: Because human bone marrow (BM) CD34+ stem cells home into damaged tissue and may play an important role in tissue repair, this pilot clinical trial explored the safety and feasibility of intravitreal autologous CD34+ BM cells as potential therapy for ischemic or degenerative retinal conditions. METHODS: This prospective study enrolled six subjects (six eyes) with irreversible vision loss from retinal vascular occlusion, hereditary or nonexudative age-related macular degeneration, or retinitis pigmentosa. CD34+ cells were isolated under Good Manufacturing Practice conditions from the mononuclear cellular fraction of the BM aspirate using a CliniMACs magnetic cell sorter. After intravitreal CD34+ cell injection, serial ophthalmic examinations, microperimetry/perimetry, fluorescein angiography, electroretinography (ERG), optical coherence tomography (OCT), and adaptive optics OCT were performed during the 6-month follow-up. RESULTS: A mean of 3.4 million (range, 1-7 million) CD34+ cells were isolated and injected per eye. The therapy was well tolerated with no intraocular inflammation or hyperproliferation. Best-corrected visual acuity and full-field ERG showed no worsening after 6 months. Clinical examination also showed no worsening during follow-up except among age-related macular degeneration subjects in whom mild progression of geographic atrophy was noted in both the study eye and contralateral eye at 6-month follow-up, concurrent with some possible decline on multifocal ERG and microperimetry. Cellular in vivo imaging using adaptive optics OCT showed changes suggestive of new cellular incorporation into the macula of the hereditary macular degeneration study eye. CONCLUSIONS: Intravitreal autologous BM CD34+ cell therapy appears feasible and well tolerated in eyes with ischemic or degenerative retinal conditions and merits further exploration. (ClinicalTrials.gov number, NCT01736059.). PMID: 25491299 [PubMed - indexed for MEDLINE]
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Related Articles Stem cells as tools for studying the genetics of inherited retinal degenerations. Cold Spring Harb Perspect Med. 2014 Dec 11;5(5):a017160 Authors: Wiley LA, Burnight ER, Mullins RF, Stone EM, Tucker BA Abstract The ability to provide early clinical intervention for inherited disorders is heavily dependent on knowledge of a patient's disease-causing mutations and the resultant pathophysiologic mechanism(s). Without knowing a patient's disease-causing gene, and how gene mutations alter the health and functionality of affected cells, it would be difficult to develop and deliver patient-specific molecular or small molecule therapies. Many believe that the field of stem cell biology holds the keys to the future development of disease-, patient-, and cell-specific therapies. In the case of the eye, which is susceptible to an extremely common late-onset degenerative disease known as age-related macular degeneration, stem cell-based therapies could increase the quality of life for millions of patients worldwide. Furthermore, autologous, patient-specific induced pluripotent stem cells could be a viable source to treat rare Mendelian retinal degenerative diseases such as retinitis pigmentosa, Stargardt disease, and Best disease, to name a few. PMID: 25502747 [PubMed - indexed for MEDLINE]
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Related Articles Enhanced differentiation and delivery of mouse retinal progenitor cells using a micropatterned biodegradable thin-film polycaprolactone scaffold. Tissue Eng Part A. 2015 Apr;21(7-8):1247-60 Authors: Yao J, Ko CW, Baranov PY, Regatieri CV, Redenti S, Tucker BA, Mighty J, Tao SL, Young MJ Abstract The deterioration of retinal tissue in advanced stages of retinitis pigmentosa and age-related macular degeneration and the lack of signaling cues for laminar regeneration are significant challenges highlighting the need for a tissue engineering approach to retinal repair. In this study, we fabricated a biodegradable thin-film polycaprolactone (PCL) scaffold with varying surface topographies using microfabrication techniques. Mouse retinal progenitor cells (mRPCs) cultured on PCL scaffolds exhibited enhanced potential to differentiate toward a photoreceptor fate in comparison to mRPCs cultured on control substrates, suggesting that PCL scaffolds are promising as substrates to guide differentiation of mRPCs toward a photoreceptor fate in vitro before transplantation. When cocultured with the retinal explants of rhodopsin null mice, mRPC/PCL constructs showed increased mRPC integration rates compared to directly applied dissociated mRPCs. Moreover, these mRPC/PCL constructs could be delivered into the subretinal space of rhodopsin null mice with minimal disturbance of the host retina. Whether cocultured with retinal explants or transplanted into the subretinal space, newly integrated mRPCs localized to the outer nuclear layer and expressed appropriate markers of photoreceptor fate. Thus, the PCL scaffold provides a platform to guide differentiation and organized delivery of mRPCs as a practical strategy to repair damaged retina. PMID: 25517296 [PubMed - indexed for MEDLINE]
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Related Articles Deprivation of bFGF Promotes Spontaneous Differentiation of Human Embryonic Stem Cells into Retinal Pigment Epithelial Cells. J Stem Cells. 2015;10(3):159-70 Authors: Ferguson LR, Balaiya S, Mynampati BK, Sambhav K, Chalam KV Abstract BACKGROUND: The retinal pigment epithelium (RPE), an important tissue monolayer of retina, sustains visual function and retinal homeostasis. In disease conditions such as Retinitis Pigmentosa (RP) and Age related Macular degeneration (AMD), the integrity and functional capacity of RPE monolayer is compromised. Human embryonic stem cells derived RPE (hESC-RPE) is ideal for cell based therapy because of their ability to morphologically and functionally mimic native fetal and adult RPE. However protocols for optimum culture of hESC-RPE are not well established. AIM: To describe a simplified protocol for differentiating human embryonic stem cells (hESC) into retinal pigment epithelial cells. METHODS: hESC (WA09-DL-11) cell lines were grown with standard stem cell culture protocol. After cell colonies were established, basic fibroblast growth factor (bFGF) was deprived (day 0). hESC colonies expressing pigmentation were characterized for expression of RPE65 and Zonular occludens--1 (ZO-1) with immunocytochemistry on days 0, 36, 42, 56 and 70 and western blot analysis on days 0, 40, 48, 53 and 63. In addition, morphological assessment was conducted on transformed cells longitudinally. RESULTS: Pigmented cells were noted 36 days after deprivation of bFGF from growth media. Immunofluorescence demonstrated progressive up regulation of RPE specific proteins (ZO-1 & RPE 65). Immunofluorescence of ZO-1 (in pixels) was (3.08 ± 0.31) on day 42, (5.33 ± 0.89, p = 0.0001) on day 56 and (4.87 ± 0.57, p = 0.0011) on day 70. Similarly expression of RPE 65 was (2.44 ± 0.31) on day 42, which continued to increase (4.23 ± 0.60, p = 0.0011) on day 56 and (5.59 ± 0.36, p < 0.0001) on day 70. Protein expression patterns using western blot confirmed the trends seen in immunofluorescence. Western blot analysis of ZO-1 expression (in optical density unit) was 272.57 ± 31.75 on day 40, 4212.20 ± 911.31 (p = 0.0004) on day 48, 5182.43 ± 1230.38 (p = 0.030) on day 53 and 5848.76 ± 241.04 (p < 0.0001) on day 63. Protein expression of RPE 65 was 1607.64 ± 247.76 on day 40, 2448.07 ± 152.66 on day 48 and (2341.15 ± 52.84) on day 63. hESC-RPE cells displayed a series of specific morphological changes (cytoplasmic, nuclear pigmentary and cell shape) over the course of time frame. By day 70, cells with hexagonal pattern, dark dense nucleus and uniform cytoplasm were noted in densely pigmented RPE colonies. CONCLUSION: bFGF deprivation leads to successful differentiation of hESC into RPE cells. Longitudinal transformative changes were confirmed with measurement of ZO-1 and RPE 65, specific markers of RPE. PMID: 27125061 [PubMed - indexed for MEDLINE]
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Related Articles Efficient delivery and functional expression of transfected modified mRNA in human embryonic stem cell-derived retinal pigmented epithelial cells. J Biol Chem. 2015 Feb 27;290(9):5661-72 Authors: Hansson ML, Albert S, González Somermeyer L, Peco R, Mejía-Ramírez E, Montserrat N, Izpisua Belmonte JC Abstract Gene- and cell-based therapies are promising strategies for the treatment of degenerative retinal diseases such as age-related macular degeneration, Stargardt disease, and retinitis pigmentosa. Cellular engineering before transplantation may allow the delivery of cellular factors that can promote functional improvements, such as increased engraftment or survival of transplanted cells. A current challenge in traditional DNA-based vector transfection is to find a delivery system that is both safe and efficient, but using mRNA as an alternative to DNA can circumvent these major roadblocks. In this study, we show that both unmodified and modified mRNA can be delivered to retinal pigmented epithelial (RPE) cells with a high efficiency compared with conventional plasmid delivery systems. On the other hand, administration of unmodified mRNA induced a strong innate immune response that was almost absent when using modified mRNA. Importantly, transfection of mRNA encoding a key regulator of RPE gene expression, microphthalmia-associated transcription factor (MITF), confirmed the functionality of the delivered mRNA. Immunostaining showed that transfection with either type of mRNA led to the expression of roughly equal levels of MITF, primarily localized in the nucleus. Despite these findings, quantitative RT-PCR analyses showed that the activation of the expression of MITF target genes was higher following transfection with modified mRNA compared with unmodified mRNA. Our findings, therefore, show that modified mRNA transfection can be applied to human embryonic stem cell-derived RPE cells and that the method is safe, efficient, and functional. PMID: 25555917 [PubMed - indexed for MEDLINE]
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Related Articles Rat BMSCs initiate retinal endogenous repair through NGF/TrkA signaling. Exp Eye Res. 2015 Mar;132:34-47 Authors: Jian Q, Li Y, Yin ZQ Abstract Müller cells can completely repair retinal injury by acting as endogenous stem/progenitor cells in lower-order vertebrates. However, a safe and effective approach to activate progenitor potential of retinal Müller cells in higher-order vertebrates, which rarely re-enter the cell cycle, is a bottleneck problem. In the present study, Royal College of Surgeon's (RCS) rats were subjected to rat bone marrow mesenchymal stem cells (rBMSCs) subretinal space transplantation. Electroretinography (ERG) recordings showed that the b-wave amplitudes and ONL thicknesses statistically increased after transplantation. The number of Müller cells expressing proliferative, stem/progenitor and neuronal markers significantly increased after rBMSCs transplantation in vivo or after co-culturing with rBMSCs in vitro. The cultured rBMSCs could secrete nerve growth factor (NGF). In addition, we confirmed that NGF or NGF-neutralizing antibody could activate or depress Müller cells dedifferentiation, both in vivo and in vitro. Furthermore, Müller cells expressing high levels of the NGF receptor neurotrophic tyrosine kinase receptor type 1 (TrkA) were observed in the retinas of rats transplanted with rBMSCs. Moreover, the protein expression of downstream elements of NGF/TrkA signaling, such as p-PI3K, p-Akt and p-CREB, increased in Müller cells in the retinas of rBMSCs-treated rats in vivo or in Müller cells co-cultured with rBMSCs in vitro. Blocking TrkA with K-252a reduced the number of dedifferentiated Müller cells and the expression of NGF/TrkA signaling in vitro. Thus, rBMSCs might initiate endogenous regenerative mechanisms, which may constitute a new therapeutic strategy for retinal dystrophic diseases. PMID: 25584870 [PubMed - indexed for MEDLINE]
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Related Articles Personalized therapeutic strategies for patients with retinitis pigmentosa. Expert Opin Biol Ther. 2015 Mar;15(3):391-402 Authors: Zheng A, Li Y, Tsang SH Abstract INTRODUCTION: Retinitis pigmentosa (RP) encompasses many different hereditary retinal degenerations that are caused by a vast array of different gene mutations and have highly variable disease presentations and severities. This heterogeneity poses a significant therapeutic challenge, although an answer may eventually be found through two recent innovations: induced pluripotent stem cells (iPSCs) and clustered regularly interspaced short palindromic repeats (CRISPR)/Cas genome editing. AREAS COVERED: This review discusses the wide-ranging applications of iPSCs and CRISPR-including disease modelling, diagnostics and therapeutics - with an ultimate view towards understanding how these two technologies can come together to address disease heterogeneity and orphan genes in a novel personalized medicine platform. An extensive literature search was conducted in PubMed and Google Scholar, with a particular focus on high-impact research published within the last 1 - 2 years and centered broadly on the subjects of retinal gene therapy, iPSC-derived outer retina cells, stem cell transplantation and CRISPR/Cas gene editing. EXPERT OPINION: For the retinal pigment epithelium, autologous transplantation of gene-corrected grafts derived from iPSCs may well be technically feasible in the near future. Photoreceptor transplantation faces more significant unresolved technical challenges but remains an achievable, if more distant, goal given the rapid pace of advancements in the field. PMID: 25613576 [PubMed - indexed for MEDLINE]
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Related Articles Gene expression changes during retinal development and rod specification. Mol Vis. 2015;21:61-87 Authors: Mansergh FC, Carrigan M, Hokamp K, Farrar GJ Abstract PURPOSE: Retinitis pigmentosa (RP) typically results from individual mutations in any one of >70 genes that cause rod photoreceptor cells to degenerate prematurely, eventually resulting in blindness. Gene therapies targeting individual RP genes have shown efficacy at clinical trial; however, these therapies require the surviving photoreceptor cells to be viable and functional, and may be economically feasible for only the more commonly mutated genes. An alternative potential treatment strategy, particularly for late stage disease, may involve stem cell transplants into the photoreceptor layer of the retina. Rod progenitors from postnatal mouse retinas can be transplanted and can form photoreceptors in recipient adult retinas; optimal numbers of transplantable cells are obtained from postnatal day 3-5 (P3-5) retinas. These cells can also be expanded in culture; however, this results in the loss of photoreceptor potential. Gene expression differences between postnatal retinas, cultured retinal progenitor cells (RPCs), and rod photoreceptor precursors were investigated to identify gene expression patterns involved in the specification of rod photoreceptors. METHODS: Microarrays were used to investigate differences in gene expression between cultured RPCs that have lost photoreceptor potential, P1 retinas, and fresh P5 retinas that contain significant numbers of transplantable photoreceptors. Additionally, fluorescence-activated cell sorting (FACS) sorted Rho-eGFP-expressing rod photoreceptor precursors were compared with Rho-eGFP-negative cells from the same P5 retinas. Differential expression was confirmed with quantitative polymerase chain reaction (q-PCR). RESULTS: Analysis of the microarray data sets, including the use of t-distributed stochastic neighbor embedding (t-SNE) to identify expression pattern neighbors of key photoreceptor specific genes, resulted in the identification of 636 genes differentially regulated during rod specification. Forty-four of these genes when mutated have previously been found to cause retinal disease. Although gene function in other tissues may be known, the retinal function of approximately 61% of the gene list is as yet undetermined. Many of these genes' promoters contain binding sites for the key photoreceptor transcription factors Crx and Nr2e3; moreover, the genomic clustering of differentially regulated genes appears to be non-random. CONCLUSIONS: This study aids in understanding gene expression differences between rod photoreceptor progenitors versus cultured RPCs that have lost photoreceptor potential. The results provide insights into rod photoreceptor development and should expedite the development of cell-based treatments for RP. Furthermore, the data set includes a large number of retinopathy genes; less-well-characterized genes within this data set are a resource for those seeking to identify novel retinopathy genes in patients with RP (GEO accession: GSE59201). PMID: 25678762 [PubMed - indexed for MEDLINE]
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Related Articles Protective Effects of Human iPS-Derived Retinal Pigmented Epithelial Cells in Comparison with Human Mesenchymal Stromal Cells and Human Neural Stem Cells on the Degenerating Retina in rd1 mice. Stem Cells. 2015 May;33(5):1543-53 Authors: Sun J, Mandai M, Kamao H, Hashiguchi T, Shikamura M, Kawamata S, Sugita S, Takahashi M Abstract Retinitis pigmentosa (RP) is a group of visual impairments characterized by progressive rod photoreceptor cell loss due to a genetic background. Pigment epithelium-derived factor (PEDF) predominantly secreted by the retinal pigmented epithelium (RPE) has been reported to protect photoreceptors in retinal degeneration models, including rd1. In addition, clinical trials are currently underway outside Japan using human mesenchymal stromal cells and human neural stem cells to protect photoreceptors in RP and dry age-related macular degeneration, respectively. Thus, this study aimed to investigate the rescue effects of induced pluripotent stem (iPS)-RPE cells in comparison with those types of cells used in clinical trials on photoreceptor degeneration in rd1 mice. Cells were injected into the subretinal space of immune-suppressed 2-week-old rd1 mice. The results demonstrated that human iPS-RPE cells significantly attenuated photoreceptor degeneration on postoperative days (PODs) 14 and 21 and survived longer up to at least 12 weeks after operation than the other two types of graft cells with less immune responses and apoptosis. The mean PEDF concentration in the intraocular fluid in RPE-transplanted eyes was more than 1 µg/ml at PODs 14 and 21, and this may have contributed to the protective effect of RPE transplantation. Our findings suggest that iPS-RPE cells serve as a competent source to delay photoreceptor degeneration through stable survival in degenerating ocular environment and by releasing neuroprotective factors such as PEDF. PMID: 25728228 [PubMed - indexed for MEDLINE]
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Related Articles Interactome analysis reveals that FAM161A, deficient in recessive retinitis pigmentosa, is a component of the Golgi-centrosomal network. Hum Mol Genet. 2015 Jun 15;24(12):3359-71 Authors: Di Gioia SA, Farinelli P, Letteboer SJ, Arsenijevic Y, Sharon D, Roepman R, Rivolta C Abstract Defects in FAM161A, a protein of unknown function localized at the cilium of retinal photoreceptor cells, cause retinitis pigmentosa, a form of hereditary blindness. By using different fragments of this protein as baits to screen cDNA libraries of human and bovine retinas, we defined a yeast two-hybrid-based FAM161A interactome, identifying 53 bona fide partners. In addition to statistically significant enrichment in ciliary proteins, as expected, this interactome revealed a substantial bias towards proteins from the Golgi apparatus, the centrosome and the microtubule network. Validation of interaction with key partners by co-immunoprecipitation and proximity ligation assay confirmed that FAM161A is a member of the recently recognized Golgi-centrosomal interactome, a network of proteins interconnecting Golgi maintenance, intracellular transport and centrosome organization. Notable FAM161A interactors included AKAP9, FIP3, GOLGA3, KIFC3, KLC2, PDE4DIP, NIN and TRIP11. Furthermore, analysis of FAM161A localization during the cell cycle revealed that this protein followed the centrosome during all stages of mitosis, likely reflecting a specific compartmentalization related to its role at the ciliary basal body during the G0 phase. Altogether, these findings suggest that FAM161A's activities are probably not limited to ciliary tasks but also extend to more general cellular functions, highlighting possible novel mechanisms for the molecular pathology of retinal disease. PMID: 25749990 [PubMed - indexed for MEDLINE]
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Related Articles Quality of life in patients with retinitis pigmentosa submitted to intravitreal use of bone marrow-derived stem cells (Reticell -clinical trial). Stem Cell Res Ther. 2015 Mar 14;6:29 Authors: Siqueira RC, Messias A, Messias K, Arcieri RS, Ruiz MA, Souza NF, Martins LC, Jorge R Abstract INTRODUCTION: Retinitis pigmentosa (RP) is a severe neurodegenerative disease of the retina that can lead to blindness. Even without treatment, a clinical study with the use of stem cells is currently underway and the results are being evaluated. In the present report we assess the vision-related quality of life in patients with RP submitted to intravitreal use of bone marrow-derived stem cells. METHOD: The study included 20 patients with RP submitted to intravitreal use of bone marrow-derived stem cells. We evaluate the vision-related quality of life (VRQOL) of patients using the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25). Patients were scheduled to answer the questionnaire before treatment and 3 and 12 months after treatment. RESULTS: All patients completed the survey as scheduled. There was a statistically significant improvement (P<0.05) in the quality of life of patients 3 months after treatment, whereas by the 12th month there was no statistically significant difference from baseline. CONCLUSIONS: Cell therapy with intravitreal use of bone marrow-derived stem cells can improve the quality of life of patients with RP, although the improvement is lost with time. A larger number of cases will be necessary to evaluate the repercussions of this therapy on the quality of life of these patients. TRIAL REGISTRATION: Clinicaltrials.gov: NCT01560715 . Registered March 19, 2012. PMID: 25890251 [PubMed - indexed for MEDLINE]
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Related Articles Selective elimination of mitochondrial mutations in the germline by genome editing. Cell. 2015 Apr 23;161(3):459-469 Authors: Reddy P, Ocampo A, Suzuki K, Luo J, Bacman SR, Williams SL, Sugawara A, Okamura D, Tsunekawa Y, Wu J, Lam D, Xiong X, Montserrat N, Esteban CR, Liu GH, Sancho-Martinez I, Manau D, Civico S, Cardellach F, Del Mar O'Callaghan M, Campistol J, Zhao H, Campistol JM, Moraes CT, Izpisua Belmonte JC Abstract Mitochondrial diseases include a group of maternally inherited genetic disorders caused by mutations in mtDNA. In most of these patients, mutated mtDNA coexists with wild-type mtDNA, a situation known as mtDNA heteroplasmy. Here, we report on a strategy toward preventing germline transmission of mitochondrial diseases by inducing mtDNA heteroplasmy shift through the selective elimination of mutated mtDNA. As a proof of concept, we took advantage of NZB/BALB heteroplasmic mice, which contain two mtDNA haplotypes, BALB and NZB, and selectively prevented their germline transmission using either mitochondria-targeted restriction endonucleases or TALENs. In addition, we successfully reduced human mutated mtDNA levels responsible for Leber's hereditary optic neuropathy (LHOND), and neurogenic muscle weakness, ataxia, and retinitis pigmentosa (NARP), in mammalian oocytes using mitochondria-targeted TALEN (mito-TALENs). Our approaches represent a potential therapeutic avenue for preventing the transgenerational transmission of human mitochondrial diseases caused by mutations in mtDNA. PAPERCLIP. PMID: 25910206 [PubMed - indexed for MEDLINE]
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Related Articles RPGR: Its role in photoreceptor physiology, human disease, and future therapies. Exp Eye Res. 2015 Sep;138:32-41 Authors: Megaw RD, Soares DC, Wright AF Abstract Mammalian photoreceptors contain specialised connecting cilia that connect the inner (IS) to the outer segments (OS). Dysfunction of the connecting cilia due to mutations in ciliary proteins are a common cause of the inherited retinal dystrophy retinitis pigmentosa (RP). Mutations affecting the Retinitis Pigmentosa GTPase Regulator (RPGR) protein is one such cause, affecting 10-20% of all people with RP and the majority of those with X-linked RP. RPGR is located in photoreceptor connecting cilia. It interacts with a wide variety of ciliary proteins, but its exact function is unknown. Recently, there have been important advances both in our understanding of RPGR function and towards the development of a therapy. This review summarises the existing literature on human RPGR function and dysfunction, and suggests that RPGR plays a role in the function of the ciliary gate, which controls access of both membrane and soluble proteins to the photoreceptor outer segment. We discuss key models used to investigate and treat RPGR disease and suggest that gene augmentation therapy offers a realistic therapeutic approach, although important questions still remain to be answered, while cell replacement therapy based on retinal progenitor cells represents a more distant prospect. PMID: 26093275 [PubMed - indexed for MEDLINE]
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Related Articles Using Stem Cells to Model Diseases of the Outer Retina. Comput Struct Biotechnol J. 2015;13:382-9 Authors: Yvon C, Ramsden CM, Lane A, Powner MB, da Cruz L, Coffey PJ, Carr AJ Abstract Retinal degeneration arises from the loss of photoreceptors or retinal pigment epithelium (RPE). It is one of the leading causes of irreversible blindness worldwide with limited effective treatment options. Generation of induced pluripotent stem cell (IPSC)-derived retinal cells and tissues from individuals with retinal degeneration is a rapidly evolving technology that holds a great potential for its use in disease modelling. IPSCs provide an ideal platform to investigate normal and pathological retinogenesis, but also deliver a valuable source of retinal cell types for drug screening and cell therapy. In this review, we will provide some examples of the ways in which IPSCs have been used to model diseases of the outer retina including retinitis pigmentosa (RP), Usher syndrome (USH), Leber congenital amaurosis (LCA), gyrate atrophy (GA), juvenile neuronal ceroid lipofuscinosis (NCL), Best vitelliform macular dystrophy (BVMD) and age related macular degeneration (AMD). PMID: 26106463 [PubMed]
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Related Articles Retinitis Pigmentosa Treatment with Western Medicine and Traditional Chinese Medicine Therapies. J Ophthalmol. 2015;2015:421269 Authors: Xu J, Peng Q Abstract Current management of retinitis pigmentosa (RP) includes an attempt at slowing down the degenerative process through therapies that use either Western or traditional Chinese medicine (TCM). Novel therapies in Western medicine (WM) include use of tailor-made gene therapy, transplantation of stem cells, or neuroprotection treatment. TCM treatment includes two major approaches. These are orally applied herbal decoctions and acupuncture. In fact, all TCM treatments are based on the differentiation of a symptom-complex, which is the characteristic essence of TCM. Thus, diagnosed RP may be treated via the liver, the kidney, and the spleen. The principle behind these treatments is to invigorate the blood and brighten the eyes by toning up the liver and the kidney. Also treatments to cope with deficiencies in the two concepts that are unique and fundamental to TCM are considered: Qi or "vital energy" and Yin and Yang or the harmony of all the opposite elements and forces that make up existence. In particular, the Qi deficiency that results from blood stasis is addressed in these treatments. This paper also puts forward the existing problems and the prospect of the future development on integrating TCM with WM. PMID: 26124961 [PubMed]
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Related Articles Patient-Specific iPSC-Derived RPE for Modeling of Retinal Diseases. J Clin Med. 2015 Mar 31;4(4):567-78 Authors: Nguyen HV, Li Y, Tsang SH Abstract Inherited retinal diseases, such as age-related macular degeneration and retinitis pigmentosa, are the leading cause of blindness in the developed world. Currently, treatments for these conditions are limited. Recently, considerable attention has been given to the possibility of using patient-specific induced pluripotent stem cells (iPSCs) as a treatment for these conditions. iPSCs reprogrammed from adult somatic cells offer the possibility of generating patient-specific cell lines in vitro. In this review, we will discuss the current literature pertaining to iPSC modeling of retinal disease, gene therapy of iPSC-derived retinal pigmented epithelium (RPE) cells, and retinal transplantation. We will focus on the use of iPSCs created from patients with inherited eye diseases for testing the efficacy of gene or drug-based therapies, elucidating previously unknown mechanisms and pathways of disease, and as a source of autologous cells for cell replacement. PMID: 26239347 [PubMed]
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Related Articles Use of induced pluripotent stem-cell technology to understand photoreceptor cytoskeletal dynamics in retinitis pigmentosa. Lancet. 2015 Feb 26;385 Suppl 1:S69 Authors: Megaw R, Mellough C, Wright A, Lako M, Ffrench-Constant C Abstract BACKGROUND: Retinitis pigmentosa, which affects one in 3000 people, causes blindness and has no treatment. Mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene cause 20% of all cases. Recent work suggests that RPGR, localised to the photoreceptor connecting cilium, regulates rhodopsin transport to the outer segment through its effect on the turnover of actin. We set out to establish a novel model for RPGR disease to test the hypothesis that RPGR mutations lead to retinal degeneration due to a dysregulation of the actin cytoskeleton. METHODS: Patients with RPGR mutations and their unaffected relatives were recruited and skin biopsy samples taken. Fibroblast lines were established and reprogrammed to generate induced pluripotent stem cell (iPSC) lines. A three-dimensional organogenesis protocol was optimised whereby embryoid bodies were formed and patterned towards an eye field fate in a 100-day retinal differentiation protocol, allowing three-dimensional optic cups to form. RPGR-mutated cultures were compared with their healthy controls. FINDINGS: Mutant and wild-type iPSC lines were generated and characterised. Differentiation of all lines resulted in the generation of optic cups in a self-organising manner after 100 days in culture. These cultures contained mature photoreceptors, as evidenced by morphology and both RNA and protein expression. Photoreceptor cultures from RGPR-mutated iPSCs had increased actin polymerisation compared with controls (mean confocal pixel intensity count 59·02 [SD 16·24] vs 23·70 [8·20], p=0·0081). This finding was confirmed by assessment of F-actin with western blot. Pathways regulating actin turnover were explored; western blot analysis showed a reduction in both Src and ERK phosphorylation in RGPR-mutated photoreceptor cultures. An unbiased protein array confirmed this reduction in ERK and Src activation. Several other pathways were also shown to be dysregulated in the RGPR-mutated photoreceptor cultures. INTERPRETATION: This study supports the hypothesis that RPGR mutations lead to actin dysregulation. We have identified several pathways that are interrupted in RPGR-mutant photoreceptor cultures and could be contributing to disease. This study is the first use, to our knowledge, of human iPSCs with retinitis pigmentosa-causing mutations to look at pathophysiology of disease. FUNDING: Wellcome Trust. PMID: 26312891 [PubMed]
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Related Articles Animal modelling for inherited central vision loss. J Pathol. 2016 Jan;238(2):300-10 Authors: Kostic C, Arsenijevic Y Abstract Disease-causing variants of a large number of genes trigger inherited retinal degeneration leading to photoreceptor loss. Because cones are essential for daylight and central vision such as reading, mobility, and face recognition, this review focuses on a variety of animal models for cone diseases. The pertinence of using these models to reveal genotype/phenotype correlations and to evaluate new therapeutic strategies is discussed. Interestingly, several large animal models recapitulate human diseases and can serve as a strong base from which to study the biology of disease and to assess the scale-up of new therapies. Examples of innovative approaches will be presented such as lentiviral-based transgenesis in pigs and adeno-associated virus (AAV)-gene transfer into the monkey eye to investigate the neural circuitry plasticity of the visual system. The models reported herein permit the exploration of common mechanisms that exist between different species and the identification and highlighting of pathways that may be specific to primates, including humans. PMID: 26387748 [PubMed - indexed for MEDLINE]
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Related Articles Stem cells in clinical trials for treatment of retinal degeneration. Expert Opin Biol Ther. 2016;16(1):7-14 Authors: Klassen H Abstract INTRODUCTION: After decades of basic science research involving the testing of regenerative strategies in animal models of retinal degenerative diseases, a number of clinical trials are now underway, with additional trials set to begin shortly. These efforts will evaluate the safety and preliminary efficacy of cell-based products in the eyes of patients with a number of retinal conditions, notably including age-related macular degeneration, retinitis pigmentosa and Stargardt's disease. AREAS COVERED: This review considers the scientific work and early trials with fetal cells and tissues that set the stage for the current clinical investigatory work, as well the trials themselves, specifically those either now completed, underway or close to initiation. The cells of interest include retinal pigment epithelial cells derived from embryonic stem or induced pluripotent stem cells, undifferentiated neural or retinal progenitors or cells from the vascular/bone marrow compartment or umbilical cord tissue. EXPERT OPINION: Degenerative diseases of the retina represent a popular target for emerging cell-based therapeutics and initial data from early stage clinical trials suggest that short-term safety objectives can be met in at least some cases. The question of efficacy will require additional time and testing to be adequately resolved. PMID: 26414165 [PubMed - indexed for MEDLINE]
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Related Articles Cell Cycle Proteins and Retinal Degeneration: Evidences of New Potential Therapeutic Targets. Adv Exp Med Biol. 2016;854:371-7 Authors: Arsenijevic Y Abstract During different forms of neurodegenerative diseases, including the retinal degeneration, several cell cycle proteins are expressed in the dying neurons from Drosophila to human revealing that these proteins are a hallmark of neuronal degeneration. This is true for animal models of Alzheimer's, and Parkinson's diseases, Amyotrophic Lateral Sclerosis and for Retinitis Pigmentosa as well as for acute injuries such as stroke and light damage. Longitudinal investigation and loss-of-function studies attest that cell cycle proteins participate to the process of cell death although with different impacts, depending on the disease. In the retina, inhibition of cell cycle protein action can result to massive protection. Nonetheless, the dissection of the molecular mechanisms of neuronal cell death is necessary to develop adapted therapeutic tools to efficiently protect photoreceptors as well as other neuron types. PMID: 26427434 [PubMed - indexed for MEDLINE]
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Related Articles Regenerative Medicine: Solution in Sight. Adv Exp Med Biol. 2016;854:543-8 Authors: Wang Q, Stern JH, Temple S Abstract The retina, like other central nervous system tissues, has poor regenerative properties in humans. Therefore, diseases that cause retinal cell loss, such as Age-related macular degeneration (AMD), retinitis pigmentosa (RP), Leber congenital amaurosis, Usher syndrome, glaucoma, and diabetic retinopathy, typically result in permanent visual impairment. Stem cell technologies have revolutionized our ability to produce neural cells in abundant supply. Much stem cell research effort is focused on producing the required cell types for cell replacement, or to generate disease-in-a-dish models to elucidate novel disease mechanisms for therapeutic development. Here we review the recent advances in stem cell studies relevant to producing RPE and retinal cells, and highlight future directions. PMID: 26427457 [PubMed - indexed for MEDLINE]
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Related Articles Human umbilical tissue-derived cells rescue retinal pigment epithelium dysfunction in retinal degeneration. Stem Cells. 2016 Feb;34(2):367-79 Authors: Cao J, Murat C, An W, Yao X, Lee J, Santulli-Marotto S, Harris IR, Inana G Abstract Retinal pigment epithelium (RPE) cells perform many functions crucial for retinal preservation and vision. RPE cell dysfunction results in various retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration (AMD). Currently, there are no effective treatments for retinal degeneration except for a small percentage of individuals with exudative AMD. Cell therapies targeting RPE cells are being developed in the clinic for the treatment of retinal degeneration. Subretinal injection of human umbilical tissue-derived cells (hUTC) in the Royal College of Surgeons (RCS) rat model of retinal degeneration was shown to preserve photoreceptors and visual function. However, the precise mechanism remains unclear. Here, we demonstrate that hUTC rescue phagocytic dysfunction in RCS RPE cells in vitro. hUTC secrete receptor tyrosine kinase (RTK) ligands brain-derived neurotrophic factor (BDNF), hepatocyte growth factor (HGF), and glial cell-derived neurotrophic factor (GDNF), as well as opsonizing bridge molecules milk-fat-globule-epidermal growth factor 8 (MFG-E8), growth arrest-specific 6 (Gas6), thrombospondin (TSP)-1, and TSP-2. The effect of hUTC on phagocytosis rescue in vitro is mimicked by recombinant human proteins of these factors and is abolished by siRNA-targeted gene silencing in hUTC. The bridge molecules secreted from hUTC bind to the photoreceptor outer segments and facilitate their ingestion by the RPE. This study elucidates novel cellular mechanisms for the repair of RPE function in retinal degeneration through RTK ligands and bridge molecules, and demonstrates the potential of using hUTC for the treatment of retinal degenerative diseases. PMID: 26523756 [PubMed - indexed for MEDLINE]
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Related Articles In Vivo CRISPR/Cas9 Gene Editing Corrects Retinal Dystrophy in the S334ter-3 Rat Model of Autosomal Dominant Retinitis Pigmentosa. Mol Ther. 2016 Mar;24(3):556-63 Authors: Bakondi B, Lv W, Lu B, Jones MK, Tsai Y, Kim KJ, Levy R, Akhtar AA, Breunig JJ, Svendsen CN, Wang S Abstract Reliable genome editing via Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9 may provide a means to correct inherited diseases in patients. As proof of principle, we show that CRISPR/Cas9 can be used in vivo to selectively ablate the rhodopsin gene carrying the dominant S334ter mutation (Rho(S334)) in rats that model severe autosomal dominant retinitis pigmentosa. A single subretinal injection of guide RNA/Cas9 plasmid in combination with electroporation generated allele-specific disruption of Rho(S334), which prevented retinal degeneration and improved visual function. PMID: 26666451 [PubMed - indexed for MEDLINE]
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Related Articles Concise Review: Patient-Specific Stem Cells to Interrogate Inherited Eye Disease. Stem Cells Transl Med. 2016 Feb;5(2):132-40 Authors: Giacalone JC, Wiley LA, Burnight ER, Songstad AE, Mullins RF, Stone EM, Tucker BA Abstract Whether we are driving to work or spending time with loved ones, we depend on our sense of vision to interact with the world around us. Therefore, it is understandable why blindness for many is feared above death itself. Heritable diseases of the retina, such as glaucoma, age-related macular degeneration, and retinitis pigmentosa, are major causes of blindness worldwide. The recent success of gene augmentation trials for the treatment of RPE65-associated Leber congenital amaurosis has underscored the need for model systems that accurately recapitulate disease. With the advent of patient-specific induced pluripotent stem cells (iPSCs), researchers are now able to obtain disease-specific cell types that would otherwise be unavailable for molecular analysis. In the present review, we discuss how the iPSC technology is being used to confirm the pathogenesis of novel genetic variants, interrogate the pathophysiology of disease, and accelerate the development of patient-centered treatments. Significance: Stem cell technology has created the opportunity to advance treatments for multiple forms of blindness. Researchers are now able to use a person's cells to generate tissues found in the eye. This technology can be used to elucidate the genetic causes of disease and develop treatment strategies. In the present review, how stem cell technology is being used to interrogate the pathophysiology of eye disease and accelerate the development of patient-centered treatments is discussed. PMID: 26683869 [PubMed - indexed for MEDLINE]
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Related Articles Transplantation of human embryonic stem cell-derived retinal tissue in two primate models of retinal degeneration. Proc Natl Acad Sci U S A. 2016 Jan 05;113(1):E81-90 Authors: Shirai H, Mandai M, Matsushita K, Kuwahara A, Yonemura S, Nakano T, Assawachananont J, Kimura T, Saito K, Terasaki H, Eiraku M, Sasai Y, Takahashi M Abstract Retinal transplantation therapy for retinitis pigmentosa is increasingly of interest due to accumulating evidence of transplantation efficacy from animal studies and development of techniques for the differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells into retinal tissues or cells. In this study, we aimed to assess the potential clinical utility of hESC-derived retinal tissues (hESC-retina) using newly developed primate models of retinal degeneration to obtain preparatory information regarding the potential clinical utility of these hESC-retinas in transplantation therapy. hESC-retinas were first transplanted subretinally into nude rats with or without retinal degeneration to confirm their competency as a graft to mature to form highly specified outer segment structure and to integrate after transplantation. Two focal selective photoreceptor degeneration models were then developed in monkeys by subretinal injection of cobalt chloride or 577-nm optically pumped semiconductor laser photocoagulation. The utility of the developed models and a practicality of visual acuity test developed for monkeys were evaluated. Finally, feasibility of hESC-retina transplantation was assessed in the developed monkey models under practical surgical procedure and postoperational examinations. Grafted hESC-retina was observed differentiating into a range of retinal cell types, including rod and cone photoreceptors that developed structured outer nuclear layers after transplantation. Further, immunohistochemical analyses suggested the formation of host-graft synaptic connections. The findings of this study demonstrate the clinical feasibility of hESC-retina transplantation and provide the practical tools for the optimization of transplantation strategies for future clinical applications. PMID: 26699487 [PubMed - indexed for MEDLINE]
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Related Articles Cell-Based Therapy for Degenerative Retinal Disease. Trends Mol Med. 2016 Feb;22(2):115-134 Authors: Zarbin M Abstract Stem cell-derived retinal pigment epithelium (RPE) and photoreceptors (PRs) have restored vision in preclinical models of human retinal degenerative disease. This review discusses characteristics of stem cell therapy in the eye and the challenges to clinical implementation that are being confronted today. Based on encouraging results from Phase I/II trials, the first Phase II clinical trials of stem cell-derived RPE transplantation are underway. PR transplant experiments have demonstrated restoration of visual function in preclinical models of retinitis pigmentosa and macular degeneration, but also indicate that no single approach is likely to succeed in overcoming PR loss in all cases. A greater understanding of the mechanisms controlling synapse formation as well as the immunoreactivity of transplanted retinal cells is urgently needed. PMID: 26791247 [PubMed - indexed for MEDLINE]
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Related Articles Precision Medicine: Genetic Repair of Retinitis Pigmentosa in Patient-Derived Stem Cells. Sci Rep. 2016 Jan 27;6:19969 Authors: Bassuk AG, Zheng A, Li Y, Tsang SH, Mahajan VB Abstract Induced pluripotent stem cells (iPSCs) generated from patient fibroblasts could potentially be used as a source of autologous cells for transplantation in retinal disease. Patient-derived iPSCs, however, would still harbor disease-causing mutations. To generate healthy patient-derived cells, mutations might be repaired with new gene-editing technology based on the bacterial system of clustered regularly interspersed short palindromic repeats (CRISPR)/Cas9, thereby yielding grafts that require no patient immunosuppression. We tested whether CRISPR/Cas9 could be used in patient-specific iPSCs to precisely repair an RPGR point mutation that causes X-linked retinitis pigmentosa (XLRP). Fibroblasts cultured from a skin-punch biopsy of an XLRP patient were transduced to produce iPSCs carrying the patient's c.3070G > T mutation. The iPSCs were transduced with CRISPR guide RNAs, Cas9 endonuclease, and a donor homology template. Despite the gene's repetitive and GC-rich sequences, 13% of RPGR gene copies showed mutation correction and conversion to the wild-type allele. This is the first report using CRISPR to correct a pathogenic mutation in iPSCs derived from a patient with photoreceptor degeneration. This important proof-of-concept finding supports the development of personalized iPSC-based transplantation therapies for retinal disease. PMID: 26814166 [PubMed - indexed for MEDLINE]
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Related Articles Cell therapy for retinal disease. Curr Opin Ophthalmol. 2016 May;27(3):185-90 Authors: Ehmann D, Shahlaee A, Ho AC Abstract PURPOSE OF REVIEW: The following review will provide an update on stem cell therapy with a focus on completed and ongoing human trials. RECENT FINDINGS: Significant progress has brought stem cell therapy from proof-of-concept animal models to human clinical trials. Although in its infancy, valuable safety and efficacy data are starting to emerge from trials looking at cell therapies for age-related macular degeneration, Stargardt's macular dystrophy, retinitis pigmentosa, and ischemic retinopathies. SUMMARY: Although clinical trials continue to enroll and evaluate stem cell therapy in patients with retinal diseases, preliminary results using both cellular replacement and trophic models have provided initial support for this exciting therapy. Results of these pivotal trials will form a key foundation for moving forward toward the ultimate goal of preventing blinding disease. PMID: 26859132 [PubMed - indexed for MEDLINE]
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Related Articles Hopes, Promises, and Future Directions of Gene and Cell Therapies in France. Hum Gene Ther. 2016 Feb;27(2):96-7 Authors: Cartier N, Cordelier P PMID: 26886830 [PubMed - indexed for MEDLINE]
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Related Articles Gene and Cell Therapies: Inserm at the Heart of Biomedical Revolutions. Hum Gene Ther. 2016 Feb;27(2):98-9 Authors: Lévy Y PMID: 26886831 [PubMed - indexed for MEDLINE]
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Related Articles Activation of type 5 metabotropic glutamate receptor promotes the proliferation of rat retinal progenitor cell via activation of the PI-3-K and MAPK signaling pathways. Neuroscience. 2016 May 13;322:138-51 Authors: Zhang Z, Hu F, Liu Y, Ma B, Chen X, Zhu K, Shi Y, Wei T, Xing Y, Gao Y, Lu H, Liu Y, Kang Q Abstract The metabotropic glutamate receptor 5 (mGluR5) regulates neurogenesis in the brain, but the effect of mGluR5 on retinal progenitor cells (RPCs) remains unknown. In this study, we found that mGluR5 promoted the proliferation of rat RPCs with activation of the phosphatidylinositol-3-kinase (PI-3-K) and mitogen-activated protein kinase (MAPK) signaling pathways in vitro. The mGluR5 agonist (S)-3,5-dihydroxyphenylglycine hydrate (DHPG) increased the cellular viability in a concentration- and time-dependent manner, whereas the mGluR5 antagonist 6-methyl-2-(phenylethynyl)pyridine hydrochloride (MTEP) had the opposite effect, as shown by 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine hydrochloride (MTT) assay. Treatment with DHPG (100 μM) also promoted the proliferation of RPCs, as indicated by 5-Bromo-2-deoxyUridine (BrdU) staining and flow cytometry, and likewise, MTEP (100 μM) and mGluR5 knockdown abolished the action of mGluR5 activity. Western blot demonstrated that the activation of mGluR5 enhanced the expression of Cyclin D1 and the phosphorylation level of PKC however, MTEP or mGluR5 knockdown also abrogated the effect of DHPG on RPCs. Furthermore, we found that activation of the extracellular signal-regulated protein kinase (ERK) and protein kinase B (AKT) signaling pathways was involved in the proliferation of RPC. After DHPG treatment, the levels of both p-ERK1/2 and p-AKT increased in a time-dependent manner. Then we used MTEP, mGluR5 knockdown, the ERK1/2 inhibitor U0126 and the AKT inhibitor LY294002 to pretreat the cells, and all of them clearly eliminated the influence of DHPG. These results demonstrated that mGluR5 regulates neurogenesis in RPCs through the MAPK and PI-3-K signaling pathways, and these findings may motivate a pharmacological study investigating a potential mechanism for the treatment of retinal diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). PMID: 26902516 [PubMed - indexed for MEDLINE]
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Related Articles Retinal Remodeling: Concerns, Emerging Remedies and Future Prospects. Front Cell Neurosci. 2016;10:38 Authors: Krishnamoorthy V, Cherukuri P, Poria D, Goel M, Dagar S, Dhingra NK Abstract Deafferentation results not only in sensory loss, but also in a variety of alterations in the postsynaptic circuitry. These alterations may have detrimental impact on potential treatment strategies. Progressive loss of photoreceptors in retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration, leads to several changes in the remnant retinal circuitry. Müller glial cells undergo hypertrophy and form a glial seal. The second- and third-order retinal neurons undergo morphological, biochemical and physiological alterations. A result of these alterations is that retinal ganglion cells (RGCs), the output neurons of the retina, become hyperactive and exhibit spontaneous, oscillatory bursts of spikes. This aberrant electrical activity degrades the signal-to-noise ratio in RGC responses, and thus the quality of information they transmit to the brain. These changes in the remnant retina, collectively termed "retinal remodeling", pose challenges for genetic, cellular and bionic approaches to restore vision. It is therefore crucial to understand the nature of retinal remodeling, how it affects the ability of remnant retina to respond to novel therapeutic strategies, and how to ameliorate its effects. In this article, we discuss these topics, and suggest that the pathological state of the retinal output following photoreceptor loss is reversible, and therefore, amenable to restorative strategies. PMID: 26924962 [PubMed]
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Related Articles Stem cell therapy for a debilitating retinal disorder. Lab Anim (NY). 2016 Apr;45(4):125 Authors: Niemeyer JE PMID: 27003341 [PubMed - indexed for MEDLINE]
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Related Articles Ocular Stem Cell Research from Basic Science to Clinical Application: A Report from Zhongshan Ophthalmic Center Ocular Stem Cell Symposium. Int J Mol Sci. 2016 Mar 22;17(3):415 Authors: Ouyang H, Goldberg JL, Chen S, Li W, Xu GT, Li W, Zhang K, Nussenblatt RB, Liu Y, Xie T, Chan CC, Zack DJ Abstract Stem cells hold promise for treating a wide variety of diseases, including degenerative disorders of the eye. The eye is an ideal organ for stem cell therapy because of its relative immunological privilege, surgical accessibility, and its being a self-contained system. The eye also has many potential target diseases amenable to stem cell-based treatment, such as corneal limbal stem cell deficiency, glaucoma, age-related macular degeneration (AMD), and retinitis pigmentosa (RP). Among them, AMD and glaucoma are the two most common diseases, affecting over 200 million people worldwide. Recent results on the clinical trial of retinal pigment epithelial (RPE) cells from human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) in treating dry AMD and Stargardt's disease in the US, Japan, England, and China have generated great excitement and hope. This marks the beginning of the ocular stem cell therapy era. The recent Zhongshan Ophthalmic Center Ocular Stem Cell Symposium discussed the potential applications of various stem cell types in stem cell-based therapies, drug discoveries and tissue engineering for treating ocular diseases. PMID: 27102165 [PubMed - indexed for MEDLINE]
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Related Articles Retinal regeneration by transplantation of retinal tissue derived from human embryonic or induced pluripotent stem cells. Inflamm Regen. 2016;36:2 Authors: Shirai H, Mandai M Abstract Rodent studies have recently demonstrated substantial integration of transplanted photoreceptors, with potential synaptic connection and functional restoration. Consequently, photoreceptor transplantation therapy for retinitis pigmentosa is attracting a growing interest in the field of translational research. Differentiation strategies for the formation of three-dimensional (3D) retinal tissue that are suitable for graft preparation have also been introduced via the use of human embryonic stem cells (hESCs) and human induced pluripotent stem cells. We have recently shown that hESC-derived retinal tissue (hESC-retina) can survive, mature, and potentially integrate with host secondary neurons following transplantation into two established primate models of retinal degeneration. Our data demonstrated the feasibility of deploying hESC-retina transplantation as a new remedy with which to restore the vision of patients with end-stage retinal degenerative diseases. In the present mini-review, we provide a short introduction of photoreceptor transplantation research. PMID: 29259675 [PubMed]
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Related Articles Retinal Structure Measurements as Inclusion Criteria for Stem Cell-Based Therapies of Retinal Degenerations. Invest Ophthalmol Vis Sci. 2016 04 01;57(5):ORSFn1-9 Authors: Jacobson SG, Matsui R, Sumaroka A, Cideciyan AV Abstract PURPOSE: We reviewed and illustrated the most optimal retinal structural measurements to make in stem cell clinical trials. METHODS: Optical coherence tomography (OCT) and autofluorescence (AF) imaging were used to evaluate patients with severe visual loss from nonsyndromic and syndromic retinitis pigmentosa (RP), ABCA4-Stargardt disease, and nonneovascular age-related macular degeneration (AMD). Outer nuclear layer (ONL), rod outer segment (ROS) layer, inner retina, ganglion cell layer (GCL), and nerve fiber layer (NFL) thicknesses were quantified. RESULTS: All patients had severely reduced visual acuities. Retinitis pigmentosa patients had limited visual fields; maculopathy patients had central scotomas with retained peripheral function. For the forms of RP illustrated, there was detectable albeit severely reduced ONL across the scanned retina, and normal or hyperthick GCL and NFL. Maculopathy patients had no measurable ONL centrally; it became detectable with eccentricity. Some maculopathy patients showed unexpected GCL losses. Autofluorescence imaging illustrated central losses of RPE integrity. A hypothetical scheme to relate patient data with different phases of retinal remodeling in animal models of retinal degeneration was presented. CONCLUSIONS: Stem cell science is advancing, but it is not too early to open the discussion of criteria for patient selection and monitoring. Available clinical tools, such as OCT and AF imaging, can provide inclusion/exclusion criteria and robust objective outcomes. Accepting that early trials may not lead to miraculous cures, we should be prepared to know why-scientifically and clinically-so we can improve subsequent trials. We also must determine if retinal remodeling is an impediment to efficacy. PMID: 27116670 [PubMed - indexed for MEDLINE]
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Related Articles Complication of Autologous Stem Cell Transplantation in Retinitis Pigmentosa. JAMA Ophthalmol. 2016 06 01;134(6):711-2 Authors: Boudreault K, Justus S, Lee W, Mahajan VB, Tsang SH PMID: 27149677 [PubMed - indexed for MEDLINE]
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Related Articles EPIRETINAL MEMBRANE FORMATION AFTER INTRAVITREAL AUTOLOGOUS STEM CELL IMPLANTATION IN A RETINITIS PIGMENTOSA PATIENT. Retin Cases Brief Rep. 2017 Summer;11(3):227-231 Authors: Kim JY, You YS, Kim SH, Kwon OW Abstract METHODS: A retrospective case report of a retinitis pigmentosa patient who underwent vitrectomy for epiretinal membrane after intravitreal autologous stem cell implantation. RESULTS: A 71-year-old female RP patient came to our clinic for ophthalmic evaluation after intravitreal autologous stem cell injection. Four months ago, she underwent intravitreal autologous stem cell injection for both eyes at another hospital. New thick epiretinal membrane (ERM) with extensive macular pucker was found on her left eye. She underwent pars plana vitrectomy and membranectomy. After biopsy, many CD34-positive stem cells were detected in ERM specimen. CONCLUSION: This is the first report of ERM formation following intravitreal autologous stem cells injection. CD34-positive stem cells were detected in a human eye at 4 months after injection. Further studies are needed to determine how stem cells caused ERM and how long they would stay in the eye. PMID: 27171917 [PubMed - indexed for MEDLINE]
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Related Articles OFD1, as a Ciliary Protein, Exhibits Neuroprotective Function in Photoreceptor Degeneration Models. PLoS One. 2016;11(5):e0155860 Authors: Wang J, Chen X, Wang F, Zhang J, Li P, Li Z, Xu J, Gao F, Jin C, Tian H, Zhang J, Li W, Lu L, Xu GT Abstract Ofd1 is a newly identified causative gene for Retinitis pigmentosa (RP), a photoreceptor degenerative disease. This study aimed to examine Ofd1 localization in retina and further to investigate its function in photoreceptor degeneration models. Ofd1 localization in rat retina was examined using immunofluorescence. N-methyl-N-nitrosourea (MNU)-induced rats and Royal College of Surgeons (RCS) rats were used as photoreceptor degeneration models. The expression pattern of Ofd1, other ciliary associated genes and Wnt signaling pathway genes were examined in rat models. Furthermore, pEGFP-Ofd1-CDS and pSUPER-Ofd1-shRNA were constructed to overexpress and knockdown the expression level in 661W and R28 cells. MNU was also used to induce cell death. Cilia formation was observed using immunocytochemistry (ICC). Reactive oxygen species (ROS) were detected using the 2', 7'-Dichlorofluorescin diacetate (DCFH-DA) assay. Apoptosis genes expression was examined using qRT-PCR, Western blotting and fluorescence-activated cell sorting (FACS). Ofd1 localized to outer segments of rat retina photoreceptors. Ofd1 and other ciliary proteins expression levels increased from the 1st and 4th postnatal weeks and decreased until the 6th week in the RCS rats, while their expression consistently decreased from the 1st and 7th day in the MNU rats. Moreover, Wnt signaling pathway proteins expression was significantly up-regulated in both rat models. Knockdown of Ofd1 expression resulted in a smaller population, shorter length of cell cilia, and lower cell viability. Ofd1 overexpression partially attenuated MNU toxic effects by reducing ROS levels and mitigating apoptosis. To the best of our knowledge, this is the first study demonstrating Ofd1 localization and its function in rat retina and in retinal degeneration rat models. Ofd1 plays a role in controlling photoreceptor cilium length and number. Importantly, it demonstrates a neuroprotective function by protecting the photoreceptor from oxidative stress and apoptosis. These data have expanded our understanding of Ofd1 function beyond cilia, and we concluded that ofd1 neuroprotection could be a potential treatment strategy in retina degeneration models. PMID: 27196396 [PubMed - indexed for MEDLINE]
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Related Articles Human neural progenitor cells decrease photoreceptor degeneration, normalize opsin distribution and support synapse structure in cultured porcine retina. Brain Res. 2016 09 01;1646:522-534 Authors: Mollick T, Mohlin C, Johansson K Abstract Retinal neurodegenerative disorders like retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy and retinal detachment decrease retinal functionality leading to visual impairment. The pathological events are characterized by photoreceptor degeneration, synaptic disassembly, remodeling of postsynaptic neurons and activation of glial cells. Despite intense research, no effective treatment has been found for these disorders. The current study explores the potential of human neural progenitor cell (hNPC) derived factors to slow the degenerative processes in adult porcine retinal explants. Retinas were cultured for 3 days with or without hNPCs as a feeder layer and investigated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), immunohistochemical, western blot and quantitative real time-polymerase chain reaction (qRT-PCR) techniques. TUNEL showed that hNPCs had the capacity to limit photoreceptor cell death. Among cone photoreceptors, hNPC coculture resulted in better maintenance of cone outer segments and reduced opsin mislocalization. Additionally, maintained synaptic structural integrity and preservation of second order calbindin positive horizontal cells was also observed. However, Müller cell gliosis only seemed to be alleviated in terms of reduced Müller cell density. Our observations indicate that at 3 days of coculture, hNPC derived factors had the capacity to protect photoreceptors, maintain synaptic integrity and support horizontal cell survival. Human neural progenitor cell applied treatment modalities may be an effective strategy to help maintain retinal functionality in neurodegenerative pathologies. Whether hNPCs can independently hinder Müller cell gliosis by utilizing higher concentrations or by combination with other pharmacological agents still needs to be determined. PMID: 27369448 [PubMed - indexed for MEDLINE]
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Related Articles Function of human pluripotent stem cell-derived photoreceptor progenitors in blind mice. Sci Rep. 2016 07 13;6:29784 Authors: Barnea-Cramer AO, Wang W, Lu SJ, Singh MS, Luo C, Huo H, McClements ME, Barnard AR, MacLaren RE, Lanza R Abstract Photoreceptor degeneration due to retinitis pigmentosa (RP) is a primary cause of inherited retinal blindness. Photoreceptor cell-replacement may hold the potential for repair in a completely degenerate retina by reinstating light sensitive cells to form connections that relay information to downstream retinal layers. This study assessed the therapeutic potential of photoreceptor progenitors derived from human embryonic and induced pluripotent stem cells (ESCs and iPSCs) using a protocol that is suitable for future clinical trials. ESCs and iPSCs were cultured in four specific stages under defined conditions, resulting in generation of a near-homogeneous population of photoreceptor-like progenitors. Following transplantation into mice with end-stage retinal degeneration, these cells differentiated into photoreceptors and formed a cell layer connected with host retinal neurons. Visual function was partially restored in treated animals, as evidenced by two visual behavioral tests. Furthermore, the magnitude of functional improvement was positively correlated with the number of engrafted cells. Similar efficacy was observed using either ESCs or iPSCs as source material. These data validate the potential of human pluripotent stem cells for photoreceptor replacement therapies aimed at photoreceptor regeneration in retinal disease. PMID: 27405580 [PubMed - indexed for MEDLINE]
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Related Articles [Therapeutical effect of growth-associated protein 43 (GAP43) gene-modified bone marrow mesenchymal stem cell transplantation on rat retinal degenerative diseases]. Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi. 2016 Aug;32(8):1041-4 Authors: Yang J, Xie M, Zheng W, Hu J, Qu Q Abstract Objective To investigate the potential of the treatment of growth-associated protein 43 (GAP43) gene-modified bone marrow-derived mesenchymal stem cells (BMSCs) for retinitis pigmentosa (RP). Methods BMSCs were isolated and cultured by adherence method. By transfecting GAP43 gene into BMSCs via a lentivirus vector, we got GAP43 gene-modified BMSCs. Sixty-three Royal College of Surgeons (RCS) rats were randomly divided into three groups: experimental group, negative control group and blank control group. The experimental rats received subretinal injection of GAP43 gene-modified BMSCs. The negative control rats received subretinal injection of BMSCs. The control rats received subretinal injection of PBS. Thirty days after transplanting, the retinal thickness was detected by optical coherence tomography (OCT), and the expression of rhodopsin in RCS rat retinas was examined by Western blotting. Results Compared with the blank control group and the negative control group, 30 days after GAP43 gene-modified BMSC transplantation, the retinal thickness of the experimental group remarkably increased and the expression of rhodopsin significantly rose. Conclusion GAP43 gene-modified BMSC transplantation can increase survival photoreceptor cells and delay retinal degeneration. PMID: 27412933 [PubMed - indexed for MEDLINE]
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Related Articles Signaling Networks of Retinal Ganglion Cell Formation and the Potential Application of Stem Cell-Based Therapy in Retinal Degenerative Diseases. Hum Gene Ther. 2016 08;27(8):609-20 Authors: Wu N, Wang Y, Yang L, Cho KS Abstract Retinal degenerative diseases such as age-related macular degeneration, retinitis pigmentosa, and glaucoma result in permanent loss of retinal neurons and vision. Stem cell therapy could be a novel treatment strategy to restore visual function. In an ideal situation, a homogenous population of stem cell-derived retinal neurons with high purity is used for replacement therapy. Thus, it is crucial to elucidate the molecular mechanisms that regulate the development of retinal progenitor cells and subsequent generation of specific retinal neurons. Here, recent findings concerning the intrinsic and extrinsic factors that regulate retinal progenitor cell maintenance and differentiation are summarized, especially transcriptional factors and extrinsic signals. Understanding these mechanisms is indispensable because they have potential clinical applications, chiefly the generation of specific retinal cells such as retinal ganglion cells to treat glaucoma and other optic neuropathy diseases. PMID: 27466076 [PubMed - indexed for MEDLINE]
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Related Articles cGMP production of patient-specific iPSCs and photoreceptor precursor cells to treat retinal degenerative blindness. Sci Rep. 2016 07 29;6:30742 Authors: Wiley LA, Burnight ER, DeLuca AP, Anfinson KR, Cranston CM, Kaalberg EE, Penticoff JA, Affatigato LM, Mullins RF, Stone EM, Tucker BA Abstract Immunologically-matched, induced pluripotent stem cell (iPSC)-derived photoreceptor precursor cells have the potential to restore vision to patients with retinal degenerative diseases like retinitis pigmentosa. The purpose of this study was to develop clinically-compatible methods for manufacturing photoreceptor precursor cells from adult skin in a non-profit cGMP environment. Biopsies were obtained from 35 adult patients with inherited retinal degeneration and fibroblast lines were established under ISO class 5 cGMP conditions. Patient-specific iPSCs were then generated, clonally expanded and validated. Post-mitotic photoreceptor precursor cells were generated using a stepwise cGMP-compliant 3D differentiation protocol. The recapitulation of the enhanced S-cone phenotype in retinal organoids generated from a patient with NR2E3 mutations demonstrated the fidelity of these protocols. Transplantation into immune compromised animals revealed no evidence of abnormal proliferation or tumor formation. These studies will enable clinical trials to test the safety and efficiency of patient-specific photoreceptor cell replacement in humans. PMID: 27471043 [PubMed - indexed for MEDLINE]
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Related Articles Retinitis Pigmentosa: Progress and Perspective. Asia Pac J Ophthalmol (Phila). 2016 Jul-Aug;5(4):265-71 Authors: Zhang Q Abstract Retinitis pigmentosa is the most common form of hereditary retinal degeneration causing blindness. Great progress has been made in the identification of the causative genes. Gene diagnosis will soon become an affordable routine clinical test because of the wide application of next-generation sequencing. Gene-based therapy provides hope for curing the disease. Investigation into the molecular pathways from mutation to rod cell death may reveal targets for developing new treatment. Related progress with existing systematic review is briefly summarized so that readers may find the relevant references for in-depth reading. Future trends in the study of retinitis pigmentosa are also discussed. PMID: 27488069 [PubMed - indexed for MEDLINE]
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Related Articles Mutations in CEP78 Cause Cone-Rod Dystrophy and Hearing Loss Associated with Primary-Cilia Defects. Am J Hum Genet. 2016 Sep 01;99(3):770-776 Authors: Nikopoulos K, Farinelli P, Giangreco B, Tsika C, Royer-Bertrand B, Mbefo MK, Bedoni N, Kjellström U, El Zaoui I, Di Gioia SA, Balzano S, Cisarova K, Messina A, Decembrini S, Plainis S, Blazaki SV, Khan MI, Micheal S, Boldt K, Ueffing M, Moulin AP, Cremers FPM, Roepman R, Arsenijevic Y, Tsilimbaris MK, Andréasson S, Rivolta C Abstract Cone-rod degeneration (CRD) belongs to the disease spectrum of retinal degenerations, a group of hereditary disorders characterized by an extreme clinical and genetic heterogeneity. It mainly differentiates from other retinal dystrophies, and in particular from the more frequent disease retinitis pigmentosa, because cone photoreceptors degenerate at a higher rate than rod photoreceptors, causing severe deficiency of central vision. After exome analysis of a cohort of individuals with CRD, we identified biallelic mutations in the orphan gene CEP78 in three subjects from two families: one from Greece and another from Sweden. The Greek subject, from the island of Crete, was homozygous for the c.499+1G>T (IVS3+1G>T) mutation in intron 3. The Swedish subjects, two siblings, were compound heterozygotes for the nearby mutation c.499+5G>A (IVS3+5G>A) and for the frameshift-causing variant c.633delC (p.Trp212Glyfs(∗)18). In addition to CRD, these three individuals had hearing loss or hearing deficit. Immunostaining highlighted the presence of CEP78 in the inner segments of retinal photoreceptors, predominantly of cones, and at the base of the primary cilium of fibroblasts. Interaction studies also showed that CEP78 binds to FAM161A, another ciliary protein associated with retinal degeneration. Finally, analysis of skin fibroblasts derived from affected individuals revealed abnormal ciliary morphology, as compared to that of control cells. Altogether, our data strongly suggest that mutations in CEP78 cause a previously undescribed clinical entity of a ciliary nature characterized by blindness and deafness but clearly distinct from Usher syndrome, a condition for which visual impairment is due to retinitis pigmentosa. PMID: 27588451 [PubMed - indexed for MEDLINE]
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Related Articles Reprogramming towards anabolism impedes degeneration in a preclinical model of retinitis pigmentosa. Hum Mol Genet. 2016 10 01;25(19):4244-4255 Authors: Zhang L, Justus S, Xu Y, Pluchenik T, Hsu CW, Yang J, Duong JK, Lin CS, Jia Y, Bassuk AG, Mahajan VB, Tsang SH Abstract Retinitis pigmentosa (RP) is an incurable neurodegenerative condition featuring photoreceptor death that leads to blindness. Currently, there is no approved therapeutic for photoreceptor degenerative conditions like RP and atrophic age-related macular degeneration (AMD). Although there are promising results in human gene therapy, RP is a genetically diverse disorder, such that gene-specific therapies would be practical in a small fraction of patients with RP. Here, we explore a non-gene-specific strategy that entails reprogramming photoreceptors towards anabolism by upregulating the mechanistic target of rapamycin (mTOR) pathway. We conditionally ablated the tuberous sclerosis complex 1 (Tsc1) gene, an mTOR inhibitor, in the rods of the Pde6bH620Q/H620Q preclinical RP mouse model and observed, functionally and morphologically, an improvement in the survival of rods and cones at early and late disease stages. These results elucidate the ability of reprogramming the metabolome to slow photoreceptor degeneration. This strategy may also be applicable to a wider range of neurodegenerative diseases, as enhancement of nutrient uptake is not gene-specific and is implicated in multiple pathologies. Enhancing anabolism promoted neuronal survival and function and could potentially benefit a number of photoreceptor and other degenerative conditions. PMID: 27516389 [PubMed - indexed for MEDLINE]
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Related Articles In vivo genome editing via CRISPR/Cas9 mediated homology-independent targeted integration. Nature. 2016 12 01;540(7631):144-149 Authors: Suzuki K, Tsunekawa Y, Hernandez-Benitez R, Wu J, Zhu J, Kim EJ, Hatanaka F, Yamamoto M, Araoka T, Li Z, Kurita M, Hishida T, Li M, Aizawa E, Guo S, Chen S, Goebl A, Soligalla RD, Qu J, Jiang T, Fu X, Jafari M, Esteban CR, Berggren WT, Lajara J, Nuñez-Delicado E, Guillen P, Campistol JM, Matsuzaki F, Liu GH, Magistretti P, Zhang K, Callaway EM, Zhang K, Belmonte JC Abstract Targeted genome editing via engineered nucleases is an exciting area of biomedical research and holds potential for clinical applications. Despite rapid advances in the field, in vivo targeted transgene integration is still infeasible because current tools are inefficient, especially for non-dividing cells, which compose most adult tissues. This poses a barrier for uncovering fundamental biological principles and developing treatments for a broad range of genetic disorders. Based on clustered regularly interspaced short palindromic repeat/Cas9 (CRISPR/Cas9) technology, here we devise a homology-independent targeted integration (HITI) strategy, which allows for robust DNA knock-in in both dividing and non-dividing cells in vitro and, more importantly, in vivo (for example, in neurons of postnatal mammals). As a proof of concept of its therapeutic potential, we demonstrate the efficacy of HITI in improving visual function using a rat model of the retinal degeneration condition retinitis pigmentosa. The HITI method presented here establishes new avenues for basic research and targeted gene therapies. PMID: 27851729 [PubMed - indexed for MEDLINE]
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Related Articles Gene and cell-based therapies for inherited retinal disorders: An update. Am J Med Genet C Semin Med Genet. 2016 12;172(4):349-366 Authors: Sengillo JD, Justus S, Tsai YT, Cabral T, Tsang SH Abstract Retinal degenerations present a unique challenge as disease progression is irreversible and the retina has little regenerative potential. No current treatments for inherited retinal disease have the ability to reverse blindness, and current dietary supplement recommendations only delay disease progression with varied results. However, the retina is anatomically accessible and capable of being monitored at high resolution in vivo. This, in addition to the immune-privileged status of the eye, has put ocular disease at the forefront of advances in gene- and cell-based therapies. This review provides an update on gene therapies and randomized control trials for inherited retinal disease, including Leber congenital amaurosis, choroideremia, retinitis pigmentosa, Usher syndrome, X-linked retinoschisis, Leber hereditary optic neuropathy, and achromatopsia. New gene-modifying and cell-based strategies are also discussed. © 2016 Wiley Periodicals, Inc. PMID: 27862925 [PubMed - indexed for MEDLINE]
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Related Articles Subretinal adipose tissue-derived mesenchymal stem cell implantation in advanced stage retinitis pigmentosa: a phase I clinical safety study. Stem Cell Res Ther. 2016 12 01;7(1):178 Authors: Oner A, Gonen ZB, Sinim N, Cetin M, Ozkul Y Abstract BACKGROUND: This prospective clinical case series aimed to investigate the safety of subretinal adipose tissue-derived mesenchymal stem cell (ADMSC) implantation in advanced stage retinitis pigmentosa (RP). METHODS: This study included 11 patients with end-stage RP who received subretinal implantation of ADMSCs. All patients had a total visual field defect and five of them only had light perception. The best corrected visual acuity (BCVA) in the study was 20/2000. All patients had undetectable electroretinography (ERG). The worst eye of the patient was operated on and, after total vitrectomy with a 23 gauge, ADMSCs were injected subretinally. Patients were evaluated at day 1, at weeks 1-4, and then once a month for 6 months, postoperatively. BCVA, anterior segment and fundus examination, color photography, and optical coherence tomography (OCT) were carried out at each visit. Fundus fluorescein angiography (FFA), perimetry, and ERG recordings were performed before treatment and at the end of month 6, and anytime if necessary during the follow-up. RESULTS: All 11 patients completed the 6-month follow-up. None of them had systemic complications. Five patients had no ocular complications. One of the patients experienced choroidal neovascular membrane (CNM) at the implantation site and received an intravitreal anti-vascular endothelial growth factor drug once. Five patients had epiretinal membrane around the transplantation area and at the periphery, and received a second vitrectomy and silicon oil injection. There was no statistically significant difference in BCVA and ERG recordings from baseline. Only one patient experienced an improvement in visual acuity (from 20/2000 to 20/200), visual field, and ERG. Three patients mentioned that the light and some colors were brighter than before and there was a slight improvement in BCVA. The remaining seven patients had no BCVA improvement (five of them only had light perception before surgery). CONCLUSIONS: Stem cell treatment with subretinal implantation of ADMSCs seems to have some ocular complications and should be applied with caution. The results of this study provide the first evidence of the short-term safety of ADMSCs in humans, and clarifies the complications of the therapy which would be beneficial for future studies. To optimize the cell delivery technique and to evaluate the effects of this therapy on visual acuity and the quality of life of these patients, future studies with a larger number of cases will be necessary. PMID: 27906070 [PubMed - indexed for MEDLINE]
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Related Articles Immunosuppression via Loss of IL2rγ Enhances Long-Term Functional Integration of hESC-Derived Photoreceptors in the Mouse Retina. Cell Stem Cell. 2017 03 02;20(3):374-384.e5 Authors: Zhu J, Cifuentes H, Reynolds J, Lamba DA Abstract Loss of photoreceptors is a common endpoint in degenerative retinal diseases. Human pluripotent stem cells provide a potential source for photoreceptor replacement, but, even in mouse models, the efficiency and efficacy of transplantation-based repair remains poor. In this study, we examined the degree to which immune rejection contributes to these disappointing outcomes using an immunodeficient IL2 receptor γ (IL2rγ)-null mouse model. Our results show that prevention of cell rejection in the normal and degenerating retinal environment significantly improves long-term survival and integration of hESC-derived donor retinal cells. Transplanted cells are able to differentiate into mature photoreceptors expressing various opsins and can functionally integrate into congenitally blind mice. Our work suggests that even though the retina is often considered immune-privileged, suppression of host immune-mediated cell rejection may well be a useful approach for improving long-term integration of transplanted cells with a view to successful clinical outcomes. PMID: 28089909 [PubMed - indexed for MEDLINE]
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Related Articles Cell-based therapeutic strategies for replacement and preservation in retinal degenerative diseases. Prog Retin Eye Res. 2017 05;58:1-27 Authors: Jones MK, Lu B, Girman S, Wang S Abstract Cell-based therapeutics offer diverse options for treating retinal degenerative diseases, such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP). AMD is characterized by both genetic and environmental risks factors, whereas RP is mainly a monogenic disorder. Though treatments exist for some patients with neovascular AMD, a majority of retinal degenerative patients have no effective therapeutics, thus indicating a need for universal therapies to target diverse patient populations. Two main cell-based mechanistic approaches are being tested in clinical trials. Replacement therapies utilize cell-derived retinal pigment epithelial (RPE) cells to supplant lost or defective host RPE cells. These cells are similar in morphology and function to native RPE cells and can potentially supplant the responsibilities of RPE in vivo. Preservation therapies utilize supportive cells to aid in visual function and photoreceptor preservation partially by neurotrophic mechanisms. The goal of preservation strategies is to halt or slow the progression of disease and maintain remaining visual function. A number of clinical trials are testing the safety of replacement and preservation cell therapies in patients; however, measures of efficacy will need to be further evaluated. In addition, a number of prevailing concerns with regards to the immune-related response, longevity, and functionality of the grafted cells will need to be addressed in future trials. This review will summarize the current status of cell-based preclinical and clinical studies with a focus on replacement and preservation strategies and the obstacles that remain regarding these types of treatments. PMID: 28111323 [PubMed - indexed for MEDLINE]
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Related Articles Insights from Genetic Model Systems of Retinal Degeneration: Role of Epsins in Retinal Angiogenesis and VEGFR2 Signaling. J Nat Sci. 2017 Jan;3(1): Authors: Dong Y, Cai X, Wu Y, Liu Y, Deng L, Chen H Abstract The retina is a light sensitive tissue that contains specialized photoreceptor cells called rods and cones which process visual signals. These signals are relayed to the brain through interneurons and the fibers of the optic nerve. The retina is susceptible to a variety of degenerative diseases, including age-related macular degeneration (AMD), diabetic retinopathy (DR), retinitis pigmentosa (RP) and other inherited retinal degenerations. In order to reveal the mechanism underlying these diseases and to find methods for the prevention/treatment of retinal degeneration, animal models have been generated to mimic human eye diseases. In this paper, several well-characterized and commonly used animal models are reviewed. Of particular interest are the contributions of these models to our understanding of the mechanisms of retinal degeneration and thereby providing novel treatment options including gene therapy, stem cell therapy, nanomedicine, and CRISPR/Cas9 genome editing. Role of newly-identified adaptor protein epsins from our laboratory is discussed in retinal angiogenesis and VEGFR2 signaling. PMID: 28191500 [PubMed]
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Related Articles Multimodal Delivery of Isogenic Mesenchymal Stem Cells Yields Synergistic Protection from Retinal Degeneration and Vision Loss. Stem Cells Transl Med. 2017 Feb;6(2):444-457 Authors: Bakondi B, Girman S, Lu B, Wang S Abstract We previously demonstrated that subretinal injection (SRI) of isogenic mesenchymal stem cells (MSCs) reduced the severity of retinal degeneration in Royal College of Surgeons rats in a focal manner. In contrast, intravenous MSC infusion (MSCIV ) produced panoptic retinal rescue. By combining these treatments, we now show that MSCIV supplementation potentiates the MSCSRI -mediated rescue of photoreceptors and visual function. Electrophysiological recording from superior colliculi revealed 3.9-fold lower luminance threshold responses (LTRs) and 22% larger functional rescue area from combined treatment compared with MSCSRI alone. MSCIV supplementation of sham (saline) injection also improved LTRs 3.4-fold and enlarged rescue areas by 27% compared with saline alone. We confirmed the involvement of MSC chemotaxis for vision rescue by modulating C-X-C chemokine receptor 4 activity before MSCIV but without increased retinal homing. Rather, circulating platelets and lymphocytes were reduced 3 and 7 days after MSCIV , respectively. We demonstrated MSCSRI -mediated paracrine support of vision rescue by SRI of concentrated MSC-conditioned medium and assessed function by electroretinography and optokinetic response. MSC-secreted peptides increased retinal pigment epithelium (RPE) metabolic activity and clearance of photoreceptor outer segments ex vivo, which was partially abrogated by antibody blockade of trophic factors in concentrated MSC-conditioned medium, or their cognate receptors on RPE. These data support multimodal mechanisms for MSC-mediated retinal protection that differ by administration route and synergize when combined. Thus, using MSCIV as adjuvant therapy might improve cell therapies for retinal dystrophy and warrants further translational evaluation. Stem Cells Translational Medicine 2017;6:444-457. PMID: 28191768 [PubMed - in process]
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Related Articles Endoscope-Assisted and Controlled Argus II Epiretinal Prosthesis Implantation in Late-Stage Retinitis Pigmentosa: A Report of 2 Cases. Case Rep Ophthalmol. 2016 Sep-Dec;7(3):315-324 Authors: Özmert E, Demirel S Abstract Several different approaches for restoring sight in subjects who are blind due to outer retinal degeneration are currently under investigation, including stem cell therapy, gene therapy, and visual prostheses. Although many different types of visual prostheses have shown promise, to date, the Argus II Epiretinal Prosthesis System, developed in a clinical setting over the course of 10 years, is the world's first and only retinal prosthesis that has been approved by the United States Food and Drug Administration (FDA) and has been given the CE-Mark for sale within the European Economic Area (EEA). The incidence of serious adverse events from Argus II implantation decreased over time after minor changes in the implant design and improvements in the surgical steps used for the procedure had been made. In order to further decrease the scleral incision-related complications and enhance the assessment of the tack position and the contact between the array and the inner macular surface, we used an ophthalmic endoscope during the regular course of Argus II implantation surgery in 2 patients with late-stage retinitis pigmentosa in an attempt to improve the anatomical and functional outcomes. PMID: 28203188 [PubMed]
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Related Articles Mertk gene expression and photoreceptor outer segment phagocytosis by cultured rat bone marrow mesenchymal stem cells. Mol Vis. 2017;23:8-19 Authors: Peng RM, Hong J, Jin Y, Sun YZ, Sun YQ, Zhang P Abstract BACKGROUND: Bone marrow mesenchymal stem cells (BM-MSCs) are multipotential stem cells that have been used for a broad spectrum of indications. Several investigations have used BM-MSCs to promote photoreceptor survival and suggested that BM-MSCs are a potential source of cell replacement therapy for some forms of retinal degeneration. PURPOSE: To investigate the expression of the MER proto-oncogene, tyrosine kinase (Mertk), involved in the disruption of RPE phagocytosis and the onset of autosomal recessive retinitis pigmentosa in rat BM-MSCs and to compare phagocytosis of the photoreceptor outer segment (POS) by BM-MSCs and RPE cells in vitro. METHODS: MSCs were isolated from the bone marrow of Brown Norway rats. Reverse transcription-PCR (RT-PCR) and western blot analyses were used to examine the expression of Mertk. The phagocytized POS was detected with double fluorescent labeling, transmission electron microscopy, and scanning electron microscopy. RESULTS: Mertk expression did not differ among the first three passages of BM-MSCs. Mertk gene expression was greater in the BM-MSCs than the RPE cells. Mertk protein expression in the BM-MSCs was similar to that in the RPE cells in the primary passage and was greater than that in the RPE cells in the other two passages. BM-MSCs at the first three passages phagocytized the POS more strongly than the RPE cells. The process of BM-MSC phagocytosis was similar to that of the RPE cells. CONCLUSIONS: BM-MSCs may be an effective cell source for treating retinal degeneration in terms of phagocytosis of the POS. PMID: 28210098 [PubMed - indexed for MEDLINE]
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Related Articles Rescue of the MERTK phagocytic defect in a human iPSC disease model using translational read-through inducing drugs. Sci Rep. 2017 03 03;7(1):51 Authors: Ramsden CM, Nommiste B, R Lane A, Carr AF, Powner MB, J K Smart M, Chen LL, Muthiah MN, Webster AR, Moore AT, Cheetham ME, da Cruz L, Coffey PJ Abstract Inherited retinal dystrophies are an important cause of blindness, for which currently there are no effective treatments. In order to study this heterogeneous group of diseases, adequate disease models are required in order to better understand pathology and to test potential therapies. Induced pluripotent stem cells offer a new way to recapitulate patient specific diseases in vitro, providing an almost limitless amount of material to study. We used fibroblast-derived induced pluripotent stem cells to generate retinal pigment epithelium (RPE) from an individual suffering from retinitis pigmentosa associated with biallelic variants in MERTK. MERTK has an essential role in phagocytosis, one of the major functions of the RPE. The MERTK deficiency in this individual results from a nonsense variant and so the MERTK-RPE cells were subsequently treated with two translational readthrough inducing drugs (G418 & PTC124) to investigate potential restoration of expression of the affected gene and production of a full-length protein. The data show that PTC124 was able to reinstate phagocytosis of labeled photoreceptor outer segments at a reduced, but significant level. These findings represent a confirmation of the usefulness of iPSC derived disease specific models in investigating the pathogenesis and screening potential treatments for these rare blinding disorders. PMID: 28246391 [PubMed - in process]
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Related Articles [Research progress of treatment strategies for retinitis pigmentosa]. Zhonghua Yan Ke Za Zhi. 2017 Feb 11;53(2):148-153 Authors: Qian TW, Xu X Abstract Retinitis pigmentosa (RP) is a genetically heterogeneous group of hereditary retinal disorders characterized by photoreceptor cell death, associated with night blindness, vision loss, progressive peripheral visual field loss and abnormalities in the electroretinogram. A number of gene defects have so far been associated with RP, which cause a progressive loss of rod photoreceptor function, followed by cone photoreceptor dysfunction and eventually complete blindness. The rate of blindness related to RP is high. At present there is no effective therapeutic strategy for RP. In recent years, with the progress of molecular biology technique, many new therapeutic approaches have become promising. This article summarizes the pathogenesis of RP and gives a brief overview of related research progress of RP therapeutic strategies. (Chin J Ophthalmol, 2017, 53: 148-153). PMID: 28260368 [PubMed - indexed for MEDLINE]
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Related Articles Combined transplantation of human mesenchymal stem cells and human retinal progenitor cells into the subretinal space of RCS rats. Sci Rep. 2017 03 15;7(1):199 Authors: Qu L, Gao L, Xu H, Duan P, Zeng Y, Liu Y, Yin ZQ Abstract Retinitis pigmentosa (RP) is one of hereditary retinal diseases characterized by the loss of photoreceptors. Cell transplantation has been clinically applied to treat RP patients. Human retinal progenitor cells (HRPCs) and human bone marrow-derived mesenchymal stem cells (HBMSCs) are the two commonly and practically used stem cells for transplantation. Since combined transplantation could be a promising way to integrate the advantages of both stem cell types, we transplanted HRPCs and HBMSCs into the subretinal space (SRS) of Royal College of Surgeons (RCS) rats. We report that HRPCs/HBMSCs combined transplantation maintains the electroretinogram results much better than HRPCs or HBMSCs single transplantations. The thickness of outer nuclear layer also presented a better outcome in the combined transplantation. Importantly, grafted cells in the combination migrated better, both longitudinally and latitudinally, than single transplantation. The photoreceptor differentiation of grafted cells in the retina of RCS rats receiving combined transplantation also showed a higher ratio than single transplantation. Finally, activation of microglia and the gliosis of Müller cells were more effectively suppressed in combined transplantation, indicating better immunomodulatory and anti-gliosis effects. Taken together, combining the transplantation of HRPCs and HBMSCs is a more effective strategy in stem cell-based therapy for retinal degenerative diseases. PMID: 28298640 [PubMed - indexed for MEDLINE]
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Related Articles Intravitreal Injection of Bone Marrow Mesenchymal Stem Cells in Patients with Advanced Retinitis Pigmentosa; a Safety Study. J Ophthalmic Vis Res. 2017 Jan-Mar;12(1):58-64 Authors: Satarian L, Nourinia R, Safi S, Kanavi MR, Jarughi N, Daftarian N, Arab L, Aghdami N, Ahmadieh H, Baharvand H Abstract PURPOSE: To examine the safety of a single intravitreal injection of autologous bone Marrow Mesenchymal stem cells (MSCs) in patients with advanced retinitis pigmentosa (RP). METHODS: A prospective, phase I, nonrandomized, open-label study was conducted on 3 eyes of 3 volunteers with advanced RP. Visual acuity, slit-lamp examination, fundus examination, optical coherence tomography, fundus auto-fluorescence, fluorescein angiography and multifocal electroretinography were performed before and after an intravitreal injection of approximately one-million MSCs. The patients were followed for one year. Further evaluation of MSCs was performed by injection of these cells into the mouse vitreous cavity. RESULTS: No, adverse events were observed in eyes of 2 out of 3 patients after transplantation of MSCs. These patients reported improvements in perception of the light after two weeks, which lasted for 3 months. However, severe fibrous tissue proliferation was observed in the vitreous cavity and retrolental space of the third patient's eye, which led to tractional retinal detachment (TRD), iris neovascularization and formation of mature cataract. Injection of this patient's MSCs into the vitreous cavity of mice also resulted in fibrosis; however, intravitreal injections of the two other patients' cells into the mouse vitreous did not generate any fibrous tissue. CONCLUSION: Intravitreal injection of autologous bone marrow MSCs into patients' eyes with advanced RP does not meet safety standards. Major side effects of this therapy can include fibrosis and TRD. We propose thorough evaluation of MSCs prior to transplantation by intravitreal injection in the laboratory animals.\. PMID: 28299008 [PubMed]
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Related Articles Retina tissue engineering by conjunctiva mesenchymal stem cells encapsulated in fibrin gel: Hypotheses on novel approach to retinal diseases treatment. Med Hypotheses. 2017 Apr;101:75-77 Authors: Soleimannejad M, Ebrahimi-Barough S, Nadri S, Riazi-Esfahani M, Soleimani M, Tavangar SM, Ai J Abstract BACKGROUND: Retinitis pigmentosa (RP) and age related macular degeneration (AMD) are two retinal diseases that progress by photoreceptor cells death. In retinal transplantation studies, stem and progenitor cells inject into the sub retinal space or vitreous and then these cells can be migrate to the site of retinal degeneration and locate in the host retina and restitute vision. PRESENTATION OF THE HYPOTHESIS: Our hypothesis suggests that using human conjunctiva stem cells (as the source for increasing the number of human stem cells progenitor cells in retina dysfunction diseases) with fibrin gel and also assessing its relating in vitro (cellular and molecular processes) and in vivo (vision tests and pathology) could be a promising strategy for treatment of AMD and RP disorders. TESTING THE HYPOTHESIS: In this idea, we describe a novel approach for retina tissue engineering with differentiation of conjunctiva mesenchymal stem cells (CJMSCs) into photoreceptor-like cells in fibrin gel with induction medium contain taurine. For assessment of differentiation, immunocytochemistry and real time PCR are used for the expression of Rhodopsin, RPE65, Nestin as differentiated photoreceptor cell markers in 2D and 3D culture. The results show that fibrin gel will offer a proper 3D scaffold for CJMSCs derived photoreceptor cell-like cells. IMPLICATIONS OF THE HYPOTHESIS: Application of immune-privileged, readily available sources of adult stem cells like human conjunctiva stem cells with fibrin gel would be a promising strategy to increase the number of photoreceptor progenitor cells and promote involuntary angiogenesis needed in retina layer repair and regeneration. PMID: 28351499 [PubMed - indexed for MEDLINE]
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Related Articles Patient-specific induced pluripotent stem cells to evaluate the pathophysiology of TRNT1-associated Retinitis pigmentosa. Stem Cell Res. 2017 05;21:58-70 Authors: Sharma TP, Wiley LA, Whitmore SS, Anfinson KR, Cranston CM, Oppedal DJ, Daggett HT, Mullins RF, Tucker BA, Stone EM Abstract Retinitis pigmentosa (RP) is a heterogeneous group of monogenic disorders characterized by progressive death of the light-sensing photoreceptor cells of the outer neural retina. We recently identified novel hypomorphic mutations in the tRNA Nucleotidyl Transferase, CCA-Adding 1 (TRNT1) gene that cause early-onset RP. To model this disease in vitro, we generated patient-specific iPSCs and iPSC-derived retinal organoids from dermal fibroblasts of patients with molecularly confirmed TRNT1-associated RP. Pluripotency was confirmed using rt-PCR, immunocytochemistry, and a TaqMan Scorecard Assay. Mutations in TRNT1 caused reduced levels of full-length TRNT1 protein and expression of a truncated smaller protein in both patient-specific iPSCs and iPSC-derived retinal organoids. Patient-specific iPSCs and iPSC-derived retinal organoids exhibited a deficit in autophagy, as evidenced by aberrant accumulation of LC3-II and elevated levels of oxidative stress. Autologous stem cell-based disease modeling will provide a platform for testing multiple avenues of treatment in patients suffering from TRNT1-associated RP. PMID: 28390992 [PubMed - indexed for MEDLINE]
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Related Articles Wogonin induces retinal neuron-like differentiation of bone marrow stem cells by inhibiting Notch-1 signaling. Oncotarget. 2017 Apr 25;8(17):28431-28441 Authors: Shu Q, Zhuang H, Fan J, Wang X, Xu G Abstract Age-related macular degeneration and retinitis pigmentosa are major causes of irreversible vision loss in the elderly and, despite sustained efforts, current treatments are largely ineffective. Wogonin is a bioactive plant flavonoid possessing a range of beneficial properties, including neuroprotective effects. We investigated the ability of wogonin to promote retinal neuron-like differentiation of bone marrow stem cells (BMSCs) and assessed the involvement of Notch-1 signaling in this process. Cultured mouse BMSCs were left untreated or exposed to neurotrophic factors in the presence or absence of wogonin, and western blotting, RT-PCR and immunofluorescence were used to identify changes in molecular markers of stemness and neuroretinal differentiation. Proteins in the Notch-1 signaling pathway, a main negative regulator of neurogenesis, were also examined by western blotting. We found that expression of stem cell markers was reduced, while markers of mature retinal neurons, bipolar cells and photoreceptors were increased in wogonin-treated BMSCs. Wogonin also dose-dependently decreased expression of Notch-1 signaling proteins. Moreover, blockade of Notch-1 both mimicked and enhanced the effect of wogonin to facilitate BMSC differentiation into retinal neuron-like cells. Wogonin thus appears to promote retinal neuron-like differentiation of BMSCs by antagonizing the inhibitory actions of Notch-1 signaling on neurogenesis and may be useful in the treatment of retinal degenerative diseases. PMID: 28415701 [PubMed - indexed for MEDLINE]
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Related Articles The CRB1 Complex: Following the Trail of Crumbs to a Feasible Gene Therapy Strategy. Front Neurosci. 2017;11:175 Authors: Quinn PM, Pellissier LP, Wijnholds J Abstract Once considered science fiction, gene therapy is rapidly becoming scientific reality, targeting a growing number of the approximately 250 genes linked to hereditary retinal disorders such as retinitis pigmentosa and Leber's congenital amaurosis. Powerful new technologies have emerged, leading to the development of humanized models for testing and screening these therapies, bringing us closer to the goal of personalized medicine. These tools include the ability to differentiate human induced pluripotent stem cells (iPSCs) to create a "retina-in-a-dish" model and the self-formed ectodermal autonomous multi-zone, which can mimic whole eye development. In addition, highly specific gene-editing tools are now available, including the CRISPR/Cas9 system and the recently developed homology-independent targeted integration approach, which allows gene editing in non-dividing cells. Variants in the CRB1 gene have long been associated with retinopathies, and more recently the CRB2 gene has also been shown to have possible clinical relevance with respect to retinopathies. In this review, we discuss the role of the CRB protein complex in patients with retinopathy. In addition, we discuss new opportunities provided by stem cells and gene-editing tools, and we provide insight into how the retinal therapeutic pipeline can be improved. Finally, we discuss the current state of adeno-associated virus-mediated gene therapy and how it can be applied to treat retinopathies associated with mutations in CRB1. PMID: 28424578 [PubMed]
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Related Articles Progress of stem/progenitor cell-based therapy for retinal degeneration. J Transl Med. 2017 05 10;15(1):99 Authors: Tang Z, Zhang Y, Wang Y, Zhang D, Shen B, Luo M, Gu P Abstract Retinal degeneration (RD), such as age-related macular degeneration (AMD) and retinitis pigmentosa, is one of the leading causes of blindness. Presently, no satisfactory therapeutic options are available for these diseases principally because the retina and retinal pigmented epithelium (RPE) do not regenerate, although wet AMD can be prevented from further progression by anti-vascular endothelial growth factor therapy. Nevertheless, stem/progenitor cell approaches exhibit enormous potential for RD treatment using strategies mainly aimed at the rescue and replacement of photoreceptors and RPE. The sources of stem/progenitor cells are classified into two broad categories in this review, which are (1) ocular-derived progenitor cells, such as retinal progenitor cells, and (2) non-ocular-derived stem cells, including embryonic stem cells, induced pluripotent stem cells, and mesenchymal stromal cells. Here, we discuss in detail the progress in the study of four predominant stem/progenitor cell types used in animal models of RD. A short overview of clinical trials involving the stem/progenitor cells is also presented. Currently, stem/progenitor cell therapies for RD still have some drawbacks such as inhibited proliferation and/or differentiation in vitro (with the exception of the RPE) and limited long-term survival and function of grafts in vivo. Despite these challenges, stem/progenitor cells represent the most promising strategy for RD treatment in the near future. PMID: 28486987 [PubMed - indexed for MEDLINE]
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Related Articles Applications of CRISPR/Cas9 in retinal degenerative diseases. Int J Ophthalmol. 2017;10(4):646-651 Authors: Peng YQ, Tang LS, Yoshida S, Zhou YD Abstract Gene therapy is a potentially effective treatment for retinal degenerative diseases. Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has been developed as a new genome-editing tool in ophthalmic studies. Recent advances in researches showed that CRISPR/Cas9 has been applied in generating animal models as well as gene therapy in vivo of retinitis pigmentosa (RP) and leber congenital amaurosis (LCA). It has also been shown as a potential attempt for clinic by combining with other technologies such as adeno-associated virus (AAV) and induced pluripotent stem cells (iPSCs). In this review, we highlight the main points of further prospect of using CRISPR/Cas9 in targeting retinal degeneration. We also emphasize the potential applications of this technique in treating retinal degenerative diseases. PMID: 28503441 [PubMed]
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Related Articles Cellular Reparative Mechanisms of Mesenchymal Stem Cells for Retinal Diseases. Int J Mol Sci. 2017 Jul 28;18(8): Authors: Ding SLS, Kumar S, Mok PL Abstract The use of multipotent mesenchymal stem cells (MSCs) has been reported as promising for the treatment of numerous degenerative disorders including the eye. In retinal degenerative diseases, MSCs exhibit the potential to regenerate into retinal neurons and retinal pigmented epithelial cells in both in vitro and in vivo studies. Delivery of MSCs was found to improve retinal morphology and function and delay retinal degeneration. In this review, we revisit the therapeutic role of MSCs in the diseased eye. Furthermore, we reveal the possible cellular mechanisms and identify the associated signaling pathways of MSCs in reversing the pathological conditions of various ocular disorders such as age-related macular degeneration (AMD), retinitis pigmentosa, diabetic retinopathy, and glaucoma. Current stem cell treatment can be dispensed as an independent cell treatment format or with the combination of other approaches. Hence, the improvement of the treatment strategy is largely subjected by our understanding of MSCs mechanism of action. PMID: 28788088 [PubMed - indexed for MEDLINE]
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Related Articles Unusual retinopathy in a child with severe combined immune deficiency. Ophthalmic Genet. 2018 Jan-Feb;39(1):92-94 Authors: Gerth-Kahlert C, Tiwari A, Hauri-Hohl MM, Hanson JVM, Bahr A, Palmowski-Wolfe A, Güngör T, Berger W Abstract We describe a case of an infant diagnosed with severe combined immune deficiency (Adenosine Deaminase (ADA), SCID) with severe retinopathy and associated low vision in both eyes at first examination. An extensive infectious work up revealed an enterovirus infection, which suggested an early infectious and severe retinopathy. Genetic causes of congenital retinitis pigmentosa/ Leber's congenital amaurosis could be excluded by whole exome sequencing. PMID: 28812413 [PubMed - indexed for MEDLINE]
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Related Articles Local gene therapy durably restores vestibular function in a mouse model of Usher syndrome type 1G. Proc Natl Acad Sci U S A. 2017 09 05;114(36):9695-9700 Authors: Emptoz A, Michel V, Lelli A, Akil O, Boutet de Monvel J, Lahlou G, Meyer A, Dupont T, Nouaille S, Ey E, Franca de Barros F, Beraneck M, Dulon D, Hardelin JP, Lustig L, Avan P, Petit C, Safieddine S Abstract Our understanding of the mechanisms underlying inherited forms of inner ear deficits has considerably improved during the past 20 y, but we are still far from curative treatments. We investigated gene replacement as a strategy for restoring inner ear functions in a mouse model of Usher syndrome type 1G, characterized by congenital profound deafness and balance disorders. These mice lack the scaffold protein sans, which is involved both in the morphogenesis of the stereociliary bundle, the sensory antenna of inner ear hair cells, and in the mechanoelectrical transduction process. We show that a single delivery of the sans cDNA by the adenoassociated virus 8 to the inner ear of newborn mutant mice reestablishes the expression and targeting of the protein to the tips of stereocilia. The therapeutic gene restores the architecture and mechanosensitivity of stereociliary bundles, improves hearing thresholds, and durably rescues these mice from the balance defects. Our results open up new perspectives for efficient gene therapy of cochlear and vestibular disorders by showing that even severe dysmorphogenesis of stereociliary bundles can be corrected. PMID: 28835534 [PubMed - indexed for MEDLINE]
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Related Articles Subretinal Injection: A Review on the Novel Route of Therapeutic Delivery for Vitreoretinal Diseases. Ophthalmic Res. 2017;58(4):217-226 Authors: Peng Y, Tang L, Zhou Y Abstract Compared to intravitreal injection, subretinal injection has more direct effects on the targeting cells in the subretinal space, which provides a new therapeutic method for vitreoretinal diseases, especially when gene therapy and/or cell therapy is involved. To date, subretinal delivery has been widely applied by scientists and clinicians as a more precise and efficient route of ocular drug delivery for gene therapies and cell therapies including stem cells in many degenerative vitreoretinal diseases, such as retinitis pigmentosa, age-related macular degeneration, and Leber's congenital amaurosis. However, clinicians should be aware of adverse events and possible complications when performing subretinal delivery. In the present review, the subretinal injection used in vitreoretinal diseases for basic research and clinical trials is summarized and described. Different methods of subretinal delivery, as well as its benefits and challenges, are also briefly introduced. PMID: 28858866 [PubMed - indexed for MEDLINE]
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Related Articles The clinical implications of molecular monitoring and analyses of inherited retinal diseases. Expert Rev Mol Diagn. 2017 11;17(11):1009-1021 Authors: Chacón-Camacho OF, García-Montaño LA, Zenteno JC Abstract INTRODUCTION: Retinal dystrophies (RDs) are the most common cause of inherited blindness and one of the most genetically heterogeneous human diseases. RDs arise from mutations in genes involved in development and function of photoreceptors or other retinal cells. Identification of the genetic defect causing RD allows accurate diagnosis, prognosis, and counseling in affected patients. Molecular diagnosis is a tremendous challenge in RDs due to their locus and phenotypic heterogeneity. As conventional DNA sequencing approaches are impractical in such situation, Next Generation Sequencing (NGS)-based protocols are needed to identify RD-causing mutations. This is being accomplished by sequencing RD gene panels or by whole exome or whole genome sequencing approaches. Areas covered: This review discusses the current strategies for molecular diagnosis in RDs including their advantages and limitations, as well as their utility in diagnosis of non-syndromic versus syndromic RDs. Results of ongoing gene therapy protocols in RDs are also presented. Expert commentary: Molecular diagnosis in RD improves the medical management of patients. Importantly, demand for molecular screening for RDs is greatly expanding not only as a result of increasing development and availability of NGS technologies, but also of the growing number of gene-based clinical trials offering a potential treatment to patients. PMID: 28945154 [PubMed - indexed for MEDLINE]
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Related Articles Long-term safety of human retinal progenitor cell transplantation in retinitis pigmentosa patients. Stem Cell Res Ther. 2017 09 29;8(1):209 Authors: Liu Y, Chen SJ, Li SY, Qu LH, Meng XH, Wang Y, Xu HW, Liang ZQ, Yin ZQ Abstract BACKGROUND: Retinitis pigmentosa is a common genetic disease that causes retinal degeneration and blindness for which there is currently no curable treatment available. Vision preservation was observed in retinitis pigmentosa animal models after retinal stem cell transplantation. However, long-term safety studies and visual assessment have not been thoroughly tested in retinitis pigmentosa patients. METHODS: In our pre-clinical study, purified human fetal-derived retinal progenitor cells (RPCs) were transplanted into the diseased retina of Royal College of Surgeons (RCS) rats, a model of retinal degeneration. Based on these results, we conducted a phase I clinical trial to establish the safety and tolerability of transplantation of RPCs in eight patients with advanced retinitis pigmentosa. Patients were studied for 24 months. RESULTS: After RPC transplantation in RCS rats, we observed moderate recovery of vision and maintenance of the outer nuclear layer thickness. Most importantly, we did not find tumor formation or immune rejection. In the retinis pigmentosa patients given RPC injections, we also did not observe immunological rejection or tumorigenesis when immunosuppressive agents were not administered. We observed a significant improvement in visual acuity (P < 0.05) in five patients and an increase in retinal sensitivity of pupillary responses in three of the eight patients between 2 and 6 months after the transplant, but this improvement did not appear by 12 months. CONCLUSION: Our study for the first time confirmed the long-term safety and feasibility of vision repair by stem cell therapy in patients blinded by retinitis pigmentosa. TRIAL REGISTRATION: WHO Trial Registration, ChiCTR-TNRC-08000193 . Retrospectively registered on 5 December 2008. PMID: 28962643 [PubMed - indexed for MEDLINE]
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Related Articles Otx2-Genetically Modified Retinal Pigment Epithelial Cells Rescue Photoreceptors after Transplantation. Mol Ther. 2018 01 03;26(1):219-237 Authors: Kole C, Klipfel L, Yang Y, Ferracane V, Blond F, Reichman S, Millet-Puel G, Clérin E, Aït-Ali N, Pagan D, Camara H, Delyfer MN, Nandrot EF, Sahel JA, Goureau O, Léveillard T Abstract Inherited retinal degenerations are blinding diseases characterized by the loss of photoreceptors. Their extreme genetic heterogeneity complicates treatment by gene therapy. This has motivated broader strategies for transplantation of healthy retinal pigmented epithelium to protect photoreceptors independently of the gene causing the disease. The limited clinical benefit for visual function reported up to now is mainly due to dedifferentiation of the transplanted cells that undergo an epithelial-mesenchymal transition. We have studied this mechanism in vitro and revealed the role of the homeogene OTX2 in preventing dedifferentiation through the regulation of target genes. We have overexpressed OTX2 in retinal pigmented epithelial cells before their transplantation in the eye of a model of retinitis pigmentosa carrying a mutation in Mertk, a gene specifically expressed by retinal pigmented epithelial cells. OTX2 increases significantly the protection of photoreceptors as seen by histological and functional analyses. We observed that the beneficial effect of OTX2 is non-cell autonomous, and it is at least partly mediated by unidentified trophic factors. Transplantation of OTX2-genetically modified cells may be medically effective for other retinal diseases involving the retinal pigmented epithelium as age-related macular degeneration. PMID: 28988713 [PubMed - in process]
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Related Articles Perspectives of Stem Cell-Based Therapy for Age-Related Retinal Degenerative Diseases. Cell Transplant. 2017 09;26(9):1538-1541 Authors: Holan V, Hermankova B, Kossl J Abstract Retinal degenerative diseases, which include age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and glaucoma, mostly affect the elderly population and are the most common cause of decreased quality of vision or even blindness. So far, there is no satisfactory treatment protocol to prevent, stop, or cure these disorders. A great hope and promise for patients suffering from retinal diseases is represented by stem cell-based therapy that could replace diseased or missing retinal cells and support regeneration. In this respect, mesenchymal stem cells (MSCs) that can be obtained from the particular patient and used as autologous cells have turned out to be a promising stem cell type for treatment. Here we show that MSCs can differentiate into cells expressing markers of retinal cells, inhibit production of pro-inflammatory cytokines by retinal tissue, and produce a number of growth and neuroprotective factors for retinal regeneration. All of these properties make MSCs a prospective cell type for cell-based therapy of age-related retinal degenerative diseases. PMID: 29113466 [PubMed - indexed for MEDLINE]
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Related Articles Potential of Gene Editing and Induced Pluripotent Stem Cells (iPSCs) in Treatment of Retinal Diseases. Yale J Biol Med. 2017 12;90(4):635-642 Authors: Chuang K, Fields MA, Del Priore LV Abstract The advent of gene editing has introduced the ability to make changes to the genome of cells, thus allowing for correction of genetic mutations in patients with monogenic diseases. Retinal diseases are particularly suitable for the application of this new technology because many retinal diseases, such as Stargardt disease, retinitis pigmentosa (RP), and Leber congenital amaurosis (LCA), are monogenic. Moreover, gene delivery techniques such as the use of adeno-associated virus (AAV) vectors have been optimized for intraocular use, and phase III trials are well underway to treat LCA, a severe form of inherited retinal degeneration, with gene therapy. This review focuses on the use of gene editing techniques and another relatively recent advent, induced pluripotent stem cells (iPSCs), and their potential for the study and treatment of retinal disease. Investment in these technologies, including overcoming challenges such as off-target mutations and low transplanted cell integration, may allow for future treatment of many debilitating inherited retinal diseases. PMID: 29259527 [PubMed - indexed for MEDLINE]
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Related Articles Cas9/sgRNA selective targeting of the P23H Rhodopsin mutant allele for treating retinitis pigmentosa by intravitreal AAV9.PHP.B-based delivery. Hum Mol Genet. 2018 03 01;27(5):761-779 Authors: Giannelli SG, Luoni M, Castoldi V, Massimino L, Cabassi T, Angeloni D, Demontis GC, Leocani L, Andreazzoli M, Broccoli V Abstract P23H is the most common mutation in the RHODOPSIN (RHO) gene leading to a dominant form of retinitis pigmentosa (RP), a rod photoreceptor degeneration that invariably causes vision loss. Specific disruption of the disease P23H RHO mutant while preserving the wild-type (WT) functional allele would be an invaluable therapy for this disease. However, various technologies tested in the past failed to achieve effective changes and consequently therapeutic benefits. We validated a CRISPR/Cas9 strategy to specifically inactivate the P23H RHO mutant, while preserving the WT allele in vitro. We, then, translated this approach in vivo by delivering the CRISPR/Cas9 components in murine Rho+/P23H mutant retinae. Targeted retinae presented a high rate of cleavage in the P23H but not WT Rho allele. This gene manipulation was sufficient to slow photoreceptor degeneration and improve retinal functions. To improve the translational potential of our approach, we tested intravitreal delivery of this system by means of adeno-associated viruses (AAVs). To this purpose, the employment of the AAV9-PHP.B resulted the most effective in disrupting the P23H Rho mutant. Finally, this approach was translated successfully in human cells engineered with the homozygous P23H RHO gene mutation. Overall, this is a significant proof-of-concept that gene allele specific targeting by CRISPR/Cas9 technology is specific and efficient and represents an unprecedented tool for treating RP and more broadly dominant genetic human disorders affecting the eye, as well as other tissues. PMID: 29281027 [PubMed - indexed for MEDLINE]
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Related Articles Organoid technology for retinal repair. Dev Biol. 2018 01 15;433(2):132-143 Authors: Llonch S, Carido M, Ader M Abstract A major cause for vision impairment and blindness in industrialized countries is the loss of the light-sensing retinal tissue in the eye. Photoreceptor damage is one of the main characteristics found in retinal degeneration diseases, such as Retinitis Pigmentosa or age-related macular degeneration. The lack of effective therapies to stop photoreceptor loss together with the absence of significant intrinsic regeneration in the human retina converts such degenerative diseases into permanent conditions that are currently irreversible. Cell replacement by means of photoreceptor transplantation has been proposed as a potential approach to tackle cell loss in the retina. Since the first attempt of photoreceptor transplantation in humans, about twenty years ago, several research groups have focused in the development and improvement of technologies necessary to bring cell transplantation for retinal degeneration diseases to reality. Progress in recent years in the generation of human tissue derived from pluripotent stem cells (PSCs) has significantly improved our tools to study human development and disease in the dish. Particularly the availability of 3D culture systems for the generation of PSC-derived organoids, including the human retina, has dramatically increased access to human material for basic and medical research. In this review, we focus on important milestones towards the generation of transplantable photoreceptor precursors from PSC-derived retinal organoids and discuss recent pre-clinical transplantation studies using organoid-derived photoreceptors in context to related in vivo work using primary photoreceptors as donor material. Additionally, we summarize remaining challenges for developing photoreceptor transplantation towards clinical application. PMID: 29291970 [PubMed - indexed for MEDLINE]
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Related Articles Gene Correction Reverses Ciliopathy and Photoreceptor Loss in iPSC-Derived Retinal Organoids from Retinitis Pigmentosa Patients. Stem Cell Reports. 2018 Apr 10;10(4):1267-1281 Authors: Deng WL, Gao ML, Lei XL, Lv JN, Zhao H, He KW, Xia XX, Li LY, Chen YC, Li YP, Pan D, Xue T, Jin ZB Abstract Retinitis pigmentosa (RP) is an irreversible, inherited retinopathy in which early-onset nyctalopia is observed. Despite the genetic heterogeneity of RP, RPGR mutations are the most common causes of this disease. Here, we generated induced pluripotent stem cells (iPSCs) from three RP patients with different frameshift mutations in the RPGR gene, which were then differentiated into retinal pigment epithelium (RPE) cells and well-structured retinal organoids possessing electrophysiological properties. We observed significant defects in photoreceptor in terms of morphology, localization, transcriptional profiling, and electrophysiological activity. Furthermore, shorted cilium was found in patient iPSCs, RPE cells, and three-dimensional retinal organoids. CRISPR-Cas9-mediated correction of RPGR mutation rescued photoreceptor structure and electrophysiological property, reversed the observed ciliopathy, and restored gene expression to a level in accordance with that in the control using transcriptome-based analysis. This study recapitulated the pathogenesis of RPGR using patient-specific organoids and achieved targeted gene therapy of RPGR mutations in a dish as proof-of-concept evidence. PMID: 29526738 [PubMed - in process]
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Related Articles Stem Cell Treatment in Retinal Diseases: Recent Developments. Turk J Ophthalmol. 2018 Feb;48(1):33-38 Authors: Öner A Abstract Stem cells are undifferentiated cells which have the ability to self-renew and differentiate into mature cells. They are highly proliferative, implying that an unlimited number of mature cells can be generated from a given stem cell source. On this basis, stem cell replacement therapy has been evaluated in recent years as an alternative for various pathologies. Degenerative retinal diseases cause progressive visual decline which originates from continuing loss of photoreceptor cells and outer nuclear layers. Theoretically, this therapy will enable the generation of new retinal cells from stem cells to replace the damaged cells in the diseased retina. In addition, stem cells are able to perform multiple functions, such as immunoregulation, anti-apoptosis of neurons, and neurotrophin secretion. With recent progress in experimental stem cell applications, phase I/II clinical trials have been approved. These latest stem cell transplantation studies showed that this therapy is a promising approach to restore visual function in eyes with degenerative retinal diseases such as retinitis pigmentosa, Stargardts' macular dystrophy, and age-related macular degeneration. This review focuses on new developments in stem cell therapy for degenerative retinal diseases. PMID: 29576896 [PubMed]
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Related Articles Morphological and genetical changes of endothelial progenitor cells after in-vitro conversion into photoreceptors. J Photochem Photobiol B. 2018 Jun;183:127-132 Authors: Qiang S, Alsaeedi HA, Yuhong C, Yang H, Tong L, Kumar S, Higuchi A, Alarfaj AA, Munisvaradass R, Ling MP, Cheng P Abstract BACKGROUND: Retinal degeneration is a condition ensued by various ocular disorders such as artery occlusion, diabetic retinopathy, retrolental fibroplasia and retinitis pigmentosa which cause abnormal loss of photoreceptor cells and lead to eventual vision impairment. No efficient treatment has yet been found, however, the use of stem cell therapy such as bone marrow and embryonic stem cells has opened a new treatment modality for retinal degenerative diseases. The major goal of this study is to analyze the potential of endothelial progenitor cells derived from bone marrow to differentiate into retinal neural cells for regenerative medicine purposes. METHODS: In this study, endothelial progenitor cells were induced in-vitro with photoreceptor growth factor (taurine) for 21 days. Subsequently, the morphology and gene expression of CRX and RHO of the photoreceptors-induced EPCs were examined through immunostaining assay. FINDINGS: The results indicated that the induced endothelial progenitor cells demonstrated positive gene expression of CRX and RHO. Our findings suggested that EPC cells may have a high advantage in cell replacement therapy for treating eye disease, in addition to other neural diseases, and may be a suitable cell source in regenerative medicine for eye disorders. PMID: 29704860 [PubMed - indexed for MEDLINE]
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Related Articles Success of Gene Therapy in Late-Stage Treatment. Adv Exp Med Biol. 2018;1074:101-107 Authors: Koch SF, Tsang SH Abstract Retinal gene therapy has yet to achieve sustained rescue after disease onset - perhaps because transduction efficiency is insufficient ("too little") and/or the disease is too advanced ("too late") in humans. To test the latter hypothesis, we used a mouse model for retinitis pigmentosa (RP) that allowed us to restore the mutant gene in all diseased rod photoreceptor cells, thereby generating optimally treated retinas. We then treated mice at an advanced disease stage and analyzed the rescue. We showed stable, sustained rescue of photoreceptor structure and function for at least 1 year, demonstrating gene therapy efficacy after onset of degeneration. The results suggest that RP patients are treatable, even when the therapy is administered at late disease stages. PMID: 29721933 [PubMed - in process]
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Related Articles The Evaluation of BMI1 Posttranslational Modifications During Retinal Degeneration to Understand BMI1 Action on Photoreceptor Death Execution. Adv Exp Med Biol. 2018;1074:359-365 Authors: Mbefo MK, Arsenijevic Y Abstract Retinitis Pigmentosa (RP) is a class of hereditary retinal dystrophy associated with gradual visual failure and a subsequent loss of light-sensitive cells in the retina, leading to blindness. Many mutated genes were found to be causative of this disease. Despite a number of compiling efforts, the process of cell death in photoreceptors remains to be clearly elucidated. We recently reported an abnormal cell cycle reentry in photoreceptors undergoing degeneration in Rd1 mice, a model of RP, and identified the polycomb repressive complex 1 (PRC1) core component BMI1 as a critical molecular factor orchestrating the cell death mechanism. As the cell death rescue in Rd1;Bmi-1 KO mice was independent on the conventional Ink4a/Arf pathways, we now explored the structural properties of BMI1 in order to examine the differential expression of its posttranslational modifications in Rd1 retina. Our results suggest that BMI1 cell death induction in Rd1 is not related to its phosphorylation status. We therefore propose the epigenetic activity of BMI1 as an alternative route for BMI1-mediated toxicity in Rd1. PMID: 29721964 [PubMed - in process]
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Related Articles Stem Cell-Based RPE Therapy for Retinal Diseases: Engineering 3D Tissues Amenable for Regenerative Medicine. Adv Exp Med Biol. 2018;1074:625-632 Authors: Ben M'Barek K, Habeler W, Monville C Abstract Recent clinical trials based on human pluripotent stem cell-derived retinal pigment epithelium cells (hPSC-RPE cells) were clearly a success regarding safety outcomes. However the delivery strategy of a cell suspension, while being a smart implementation of a cell therapy, might not be sufficient to achieve the best results. More complex reconstructed tissue formulations are required, both to improve functionality and to target pathological conditions with altered Bruch's membrane like age-related macular degeneration (AMD). Herein, we describe the various options regarding the stem cell source choices and the different strategies elaborated in the recent years to develop engineered RPE sheets amenable for regenerative therapies. PMID: 29721996 [PubMed - in process]
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Related Articles Gene therapy and genome surgery in the retina. J Clin Invest. 2018 Jun 01;128(6):2177-2188 Authors: DiCarlo JE, Mahajan VB, Tsang SH Abstract Precision medicine seeks to treat disease with molecular specificity. Advances in genome sequence analysis, gene delivery, and genome surgery have allowed clinician-scientists to treat genetic conditions at the level of their pathology. As a result, progress in treating retinal disease using genetic tools has advanced tremendously over the past several decades. Breakthroughs in gene delivery vectors, both viral and nonviral, have allowed the delivery of genetic payloads in preclinical models of retinal disorders and have paved the way for numerous successful clinical trials. Moreover, the adaptation of CRISPR-Cas systems for genome engineering have enabled the correction of both recessive and dominant pathogenic alleles, expanding the disease-modifying power of gene therapies. Here, we highlight the translational progress of gene therapy and genome editing of several retinal disorders, including RPE65-, CEP290-, and GUY2D-associated Leber congenital amaurosis, as well as choroideremia, achromatopsia, Mer tyrosine kinase- (MERTK-) and RPGR X-linked retinitis pigmentosa, Usher syndrome, neovascular age-related macular degeneration, X-linked retinoschisis, Stargardt disease, and Leber hereditary optic neuropathy. PMID: 29856367 [PubMed - in process]
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Related Articles Regenerating Eye Tissues to Preserve and Restore Vision. Cell Stem Cell. 2018 Jun 01;22(6):834-849 Authors: Stern JH, Tian Y, Funderburgh J, Pellegrini G, Zhang K, Goldberg JL, Ali RR, Young M, Xie Y, Temple S Abstract Ocular regenerative therapies are on track to revolutionize treatment of numerous blinding disorders, including corneal disease, cataract, glaucoma, retinitis pigmentosa, and age-related macular degeneration. A variety of transplantable products, delivered as cell suspensions or as preformed 3D structures combining cells and natural or artificial substrates, are in the pipeline. Here we review the status of clinical and preclinical studies for stem cell-based repair, covering key eye tissues from front to back, from cornea to retina, and including bioengineering approaches that advance cell product manufacturing. While recognizing the challenges, we look forward to a deep portfolio of sight-restoring, stem cell-based medicine. VIDEO ABSTRACT. PMID: 29859174 [PubMed - in process]
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Related Articles Gene therapy in inherited retinal degenerative diseases, a review. Ophthalmic Genet. 2018 Oct;39(5):560-568 Authors: Takahashi VKL, Takiuti JT, Jauregui R, Tsang SH Abstract Hereditary diseases of the retina represent a group of diseases with several heterogeneous mutations that have the common end result of progressive photoreceptor death leading to blindness. Retinal degenerations encompass multifactorial diseases such as age-related macular degeneration, Leber congenital amaurosis, Stargardt disease, and retinitis pigmentosa. Although there is currently no cure for degenerative retinal diseases, ophthalmology has been at the forefront of the development of gene therapy, which offers hope for the treatment of these conditions. This article will explore an overview of the clinical trials of gene supplementation therapy for retinal diseases that are underway or planned for the near future. PMID: 30040511 [PubMed - in process]
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Related Articles Stem Cell Ophthalmology Treatment Study: bone marrow derived stem cells in the treatment of Retinitis Pigmentosa. Stem Cell Investig. 2018;5:18 Authors: Weiss JN, Levy S Abstract Background: Seventeen patients with bilateral visual loss due to Retinitis Pigmentosa (RP) underwent autologous bone marrow derived stem cell (BMSC) treatment within the Stem Cell Ophthalmology Treatment Study (SCOTS and SCOTS 2). Both are National Institutes of Health (NIH) and Office of Human Research Protection (OHRP) compliant Institutional Review Board (IRB) approved clinical studies utilizing using autologous BMSC in the treatment of retinal and optic nerve diseases that meet inclusion criteria. Methods: The average age of the patients treated was 48.8 years. The average duration of disease prior to treatment was 27.6 years and ranged from 4 to approximately 60 years. Affected eyes were treated with either retrobulbar, subtenons and intravenous BMSC or retrobulbar, subtenons, intravitreal and intravenous. Follow up was provided a minimum of 6 months. The primary outcome was visual acuity as measured by Snellen or converted to LogMAR. Results: Following therapy in SCOTS or SCOTS 2, 11 patients (64.7%) showed improved binocular vision averaging 10.23 lines of Snellen acuity per eye over pre-treatment acuity; 8 patients (35.3%) remaining stable over the follow up period; no patients experiencing loss of overall acuity. In 33 treated eyes, 15 eyes (45.5%) improved an average of 7.9 lines of Snellen acuity, 15 eyes (45.5%) remained stable, and 3 eyes (9%) worsened by an average of 1.7 lines of Snellen acuity. Improvements ranged from 1 to 27 lines of vision. Using the LogMAR Scale and calculating delta as a ratio to pre-treatment vision in improved eyes, acuity improvement ranged from 23% to 90% with an average of 40.9% visual acuity improvement over baseline vision. Evaluation of all patients and eyes capable of LogMAR vision showed an average of 31% improvement in vision over baseline. Findings were of statistical significance (P=0.016). There were no surgical complications. Conclusions: The BMSC protocols of the SCOTS achieved meaningful visual acuity improvements or stability in RP that were of statistical significance. Duration of disease did not appear to affect the ability of eyes to respond. Safety was confirmed. Possible mechanisms by which improvement occurred may include transdifferentiation of BMSC into Neuronal Nuclei (NeuN) positive cells, BMSC paracrine secretions or neurotrophic factors and hormones, transfer of mitochondria, release of messenger RNA or other compounds via exosomes or microvesicles. Given the successful outcome in this otherwise progressive condition, consideration should be given to providing this treatment option. PMID: 30050918 [PubMed]
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Related Articles The peripheral eye: A neurogenic area with potential to treat retinal pathologies? Prog Retin Eye Res. 2018 Sep 08;: Authors: Fernández-Nogales M, Murcia-Belmonte V, Chen HY, Herrera E Abstract Numerous degenerative diseases affecting visual function, including glaucoma and retinitis pigmentosa, are produced by the loss of different types of retinal cells. Cell replacement therapy has emerged as a promising strategy for treating these and other retinal diseases. The retinal margin or ciliary body (CB) of mammals has been proposed as a potential source of cells to be used in degenerative conditions affecting the retina because it has been reported it might hold neurogenic potential beyond embryonic development. However, many aspects of the origin and biology of the CB are unknown and more recent experiments have challenged the capacity of CB cells to generate different types of retinal neurons. Here we review the most recent findings about the development of the marginal zone of the retina in different vertebrates and some of the mechanisms underlying the proliferative and neurogenic capacity of this fascinating region of the vertebrates eye. In addition, we performed experiments to isolate CB cells from the mouse retina, generated neurospheres and observed that they can be expanded with a proliferative ratio similar to neural stem cells. When induced to differentiate, cells derived from the CB neurospheres start to express early neural markers but, unlike embryonic stem cells, they are not able to fully differentiate in vitro or generate retinal organoids. Together with previous reports on the neurogenic capacity of CB cells, also reviewed here, our results contribute to the current knowledge about the potentiality of this peripheral region of the eye as a therapeutic source of functional retinal neurons in degenerative diseases. PMID: 30201383 [PubMed - as supplied by publisher]
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Related Articles Application of CRISPR/Cas9 technologies combined with iPSCs in the study and treatment of retinal degenerative diseases. Hum Genet. 2018 Sep;137(9):679-688 Authors: Cai B, Sun S, Li Z, Zhang X, Ke Y, Yang J, Li X Abstract Retinal degeneration diseases, such as age-related macular degeneration and retinitis pigmentosa, affect millions of people worldwide and are major causes of irreversible blindness. Effective treatments for retinal degeneration, including drug therapy, gene augmentation or transplantation approaches, have been widely investigated. Nevertheless, more research should be dedicated to therapeutic methods to improve future clinical treatments. Recently, with the rapid development of genome-editing technology, gene therapy has become a potentially effective treatment for retinal degeneration diseases. A clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system has been developed as a powerful genome-editing tool in ophthalmic studies. The CRISPR/Cas9 system has been widely applied in basic research to develop animal models and gene therapies in vivo. With the ability to self-renew and the potential to differentiate into different types of cells, induced pluripotent stem cells (iPSCs) have already been used as a promising tool for understanding disease pathophysiology and evaluating the effect of drug and gene therapeutics. iPSCs are also a cell source for autologous transplantation. In this review, we compared genome-editing strategies and highlighted the advantages and concerns of the CRISPR/Cas9 system. Moreover, the latest progress and applications of the CRISPR/Cas9 system and its combination with iPSCs for the treatment of retinal degenerative diseases are summarized. PMID: 30203114 [PubMed - indexed for MEDLINE]
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Related Articles Retinitis pigmentosa: recent advances and future directions in diagnosis and management. Curr Opin Pediatr. 2018 Dec;30(6):725-733 Authors: Fahim A Abstract PURPOSE OF REVIEW: Retinitis pigmentosa is a group of genetically diverse inherited blinding disorders for which there are no treatments. Owing to recent advances in imaging technology, DNA sequencing, gene therapy, and stem cell biology, clinical trials have multiplied and the landscape is rapidly changing. This review provides a relevant and timely update of current trends and future directions for the diagnosis and management of this disease. RECENT FINDINGS: This review will highlight the use of retinal imaging to measure progression of disease, next-generation sequencing for genetic diagnosis, the use of electronic retinal implants as well as noninvasive digital low-vision aids, and the current state of preclinical and clinical research with gene therapy and cell-based therapies. SUMMARY: Retinitis pigmentosa has historically been an untreatable condition. Recent advances have allowed for limited improvement in visual outcomes for select patients. Retinal degenerative disease is on the cutting edge of regenerative medicine. Gene therapy and stem cell therapeutic strategies are currently under investigation and are expected to radically impact management of inherited retinal disease in the coming years. VIDEO ABSTRACT: http://links.lww.com/MOP/A33. PMID: 30234647 [PubMed - in process]
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Related Articles Engineering Transplantation-suitable Retinal Pigment Epithelium Tissue Derived from Human Embryonic Stem Cells. J Vis Exp. 2018 09 06;(139): Authors: Ben M'Barek K, Habeler W, Plancheron A, Jarraya M, Goureau O, Monville C Abstract Several pathological conditions of the eye affect the functionality and/or the survival of the retinal pigment epithelium (RPE). These include some forms of retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Cell therapy is one of the most promising therapeutic strategies proposed to cure these diseases, with already encouraging preliminary results in humans. However, the method of preparation of the graft has a significant impact on its functional outcomes in vivo. Indeed, RPE cells grafted as a cell suspension are less functional than the same cells transplanted as a retinal tissue. Herein, we describe a simple and reproducible method to engineer RPE tissue and its preparation for an in vivo implantation. RPE cells derived from human pluripotent stem cells are seeded on a biological support, the human amniotic membrane (hAM). Compared to artificial scaffolds, this support has the advantage of having a basement membrane that is close to the Bruch's membrane where endogenous RPE cells are attached. However, its manipulation is not easy, and we developed several strategies for its proper culturing and preparation for grafting in vivo. PMID: 30247475 [PubMed - indexed for MEDLINE]
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Related Articles Stemming retinal regeneration with pluripotent stem cells. Prog Retin Eye Res. 2018 Nov 09;: Authors: Jin ZB, Gao ML, Deng WL, Wu KC, Sugita S, Mandai M, Takahashi M Abstract Cell replacement therapy is a promising treatment for irreversible retinal cell death in diverse diseases, such as age-related macular degeneration (AMD), Stargardt's disease, retinitis pigmentosa (RP) and glaucoma. These diseases are all characterized by the degeneration of one or two retinal cell types that cannot regenerate spontaneously in humans. Aberrant retinal pigment epithelial (RPE) cells can be observed through optical coherence tomography (OCT) in AMD patients. In RP patients, the morphological and functional abnormalities of RPE and photoreceptor layers are caused by a genetic abnormality. Stargardt's disease or juvenile macular degeneration, which is characterized by the loss of the RPE and photoreceptors in the macular area, causes central vision loss at an early age. Loss of retinal ganglion cells (RGCs) can be observed in patients with glaucoma. Once the retinal cell degeneration is triggered, no treatments can reverse it. Transplantation-based approaches have been proposed as a universal therapy to target patients with various concomitant diseases. Both the replacement of dead cells and neuroprotection are strategies used to rescue visual function in animal models of retinal degeneration. Diverse retinal cell types derived from pluripotent stem cells, including RPE cells, photoreceptors, RGCs and even retinal organoids with a layered structure, provide unlimited cell sources for transplantation. In addition, mesenchymal stem cells (MSCs) are multifunctional and protect degenerating retinal cells. The aim of this review is to summarize current findings from preclinical and clinical studies. We begin with a brief introduction to retinal degenerative diseases and cell death in diverse diseases, followed by methods for retinal cell generation. Preclinical and clinical studies are discussed, and future concerns about efficacy, safety and immunorejection are also addressed. PMID: 30419340 [PubMed - as supplied by publisher]
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Related Articles Transplantation of photoreceptors into the degenerative retina: Current state and future perspectives. Prog Retin Eye Res. 2018 Nov 13;: Authors: Gasparini SJ, Llonch S, Borsch O, Ader M Abstract The mammalian retina displays no intrinsic regenerative capacities, therefore retinal degenerative diseases such as age-related macular degeneration (AMD) or retinitis pigmentosa (RP) result in a permanent loss of the light-sensing photoreceptor cells. The degeneration of photoreceptors leads to vision impairment and, in later stages, complete blindness. Several therapeutic strategies have been developed to slow down or prevent further retinal degeneration, however a definitive cure i.e. replacement of the lost photoreceptors, has not yet been established. Cell-based treatment approaches, by means of photoreceptor transplantation, have been studied in pre-clinical animal models over the last three decades. The introduction of pluripotent stem cell-derived retinal organoids represents, in principle, an unlimited source for the generation of transplantable human photoreceptors. However, safety, immunological and reproducibility-related issues regarding the use of such cells still need to be solved. Moreover, the recent finding of cytoplasmic material transfer between donor and host photoreceptors demands reinterpretation of several former transplantation studies. At the same time, material transfer between healthy donor and dysfunctional patient photoreceptors also offers a potential alternative strategy for therapeutic intervention. In this review we discuss the history and current state of photoreceptor transplantation, the techniques used to assess rescue of visual function, the prerequisites for effective transplantation as well as the main roadblocks, including safety and immune response to the graft, that need to be overcome for successful clinical translation of photoreceptor transplantation approaches. PMID: 30445193 [PubMed - as supplied by publisher]
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Related Articles Generation of a human iPS cell line from a patient with retinitis pigmentosa due to EYS mutation. Stem Cell Res. 2018 Dec;33:251-254 Authors: Calado SM, Garcia-Delgado AB, De la Cerda B, Ponte-Zuñiga B, Bhattacharya SS, Díaz-Corrales FJ Abstract Retinitis pigmentosa (RP) is an inherited retinal degenerative disease. Mutations in EYS have been associated with autosomal recessive RP. The human iPS cell line, CABi002-A, derived from peripheral blood mononuclear cells from a patient carrying a heterozygous double mutation in EYS gene was generated by non-integrative reprogramming technology, using hOCT3/4, hSOX2, hc-MYC and hKLF4 reprogramming factors. Pluripotency and differentiation capacity were assessed by immunocytochemistry and RT-PCR. This iPSC line can be further differentiated towards the affected cells to understand the pathophysiology of the disease and test new therapeutic strategies. PMID: 30471616 [PubMed - in process]
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Related Articles Generation of gene-corrected human induced pluripotent stem cell lines derived from retinitis pigmentosa patient with Ser331Cysfs*5 mutation in MERTK. Stem Cell Res. 2018 Nov 16;34:101341 Authors: Artero Castro A, Long K, Bassett A, Machuca C, León M, Ávila-Fernandez A, Cortón M, Vidal-Puig T, Ayuso C, Lukovic D, Erceg S Abstract The human induced pluripotent stem cell (hiPSC) line RP1-FiPS4F1 generated from the patient with autosomal recessive retinitis pigmentosa (arRP) caused by homozygous Ser331Cysfs*5 mutation in Mer tyrosine kinase receptor (MERTK) was genetically corrected using CRISPR/Cas9 system. Two isogenic hiPSCs lines, with heterozygous and homozygous correction of c.992_993delCA mutation in the MERTK gene were generated. These cell lines demonstrate normal karyotype, maintain a pluripotent state, and can differentiate toward three germ layers in vitro. These genetically corrected hiPSCs represent accurate controls to study the contribution of the specific genetic change to the disease, and potentially therapeutic material for cell-replacement therapy. PMID: 30612079 [PubMed - as supplied by publisher]
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