Adult Retinal Pigment Epithelium Research Articles

Panax ginseng Fraction F3 Extracted by Supercritical Carbon Dioxide Protects against Oxidative Stress in ARPE-19 Cells.

In our previous work, the ethanolic extract of Panax ginseng C. A. Meyer was successively partitioned using supercritical carbon dioxide at pressures in series to yield residue (R), F1, F2, and F3 fractions. Among them, F3 contained the highest deglycosylated ginsenosides and exerted the strongest antioxidant and anti-inflammatory activities. The aim of this study was to investigate the protective effects of P. ginseng fractions against cellular oxidative stress induced by hydrogen peroxide (H2O2). Viability of adult retinal pigment epithelium-19 (ARPE-19) cells was examined after treatments of different concentrations of fractions followed by exposure to H2O2. Oxidative levels (malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), and reactive oxygen species (ROS)) and levels of activity of antioxidant enzymes were assessed. Results showed that F3 could dose-dependently protected ARPE-19 cells against oxidative injury induced by H2O2. F3 at a level of 1 mg/mL could restore the cell death induced by H2O2 of up to 60% and could alleviate the increase in cellular oxidation (MDA, 8-OHdG, and ROS) induced by H2O2. Moreover, F3 could restore the activities of antioxidant enzymes suppressed by H2O2. In conclusion, F3 obtained using supercritical carbon dioxide fractionation could significantly increase the antioxidant capacity of P. ginseng extract. The antioxidant capacity was highly correlated with the concentration of F3.

The Eyes Have it! Protective Role of Prolactin in the Retina

The Eyes Have it! Protective Role of Prolactin in the Retina

Prolactin protects retinal pigment epithelium by inhibiting sirtuin 2-dependent cell death

SummaryThe identification of pathways necessary for retinal pigment epithelium (RPE) function is fundamental to uncover therapies for blindness. Prolactin (PRL) receptors are expressed in the retina, but nothing is known about the role of PRL in RPE. Using the adult RPE 19 (ARPE-19) human cell line and mouse RPE, we identified the presence of PRL receptors and demonstrated that PRL is necessary for RPE cell survival via anti-apoptotic and antioxidant actions. PRL promotes the antioxidant capacity of ARPE-19 cells by reducing glutathione. It also blocks the hydrogen peroxide-induced increase in deacetylase sirtuin 2 (SIRT2) expression, which inhibits the TRPM2-mediated intracellular Ca2+ rise associated with reduced survival under oxidant conditions. RPE from PRL receptor-null (prlr−/−) mice showed increased levels of oxidative stress, Sirt2 expression and apoptosis, effects that were exacerbated in animals with advancing age. These observations identify PRL as a regulator of RPE homeostasis.

Cytotoxicity considerations and electrically tunable release of dexamethasone from polypyrrole for the treatment of back-of-the-eye conditions.

Age-related macular degeneration (AMD) and diabetic macular edema (DME) are common causes of blindness in people aged over 55years. Current treatment involves frequent intravitreal administration of corticosteroids such as dexamethasone. The aim of this research was to formulate an electrically controlled delivery system for dexamethasone. Polypyrrole (PPy) was polymerized with dexamethasone sodium phosphate (Dex-P) through two approaches. Firstly, conventional films (CFs) of PPy were electropolymerized by applying a constant current density of 2mA/cm2 for 4min. Secondly, for the first time, we report drug-loaded ethanol-washed films (EWFs). EWFs were prepared in the same manner as CFs, except ethanol washing steps were introduced in the middle and at the end of PPy electropolymerization. The ethanol washing removed unbound PPy oligomers resulting in the formation of smooth surfaces with two distinct layers when viewed in cross-section. The EWFs showed superior electrochemical activity compared to CFs. Sustained release was observed from both CFs and EWFs with bursts of release triggered by electrical stimulation. The EWFs were initially more responsive to the electrical trigger, offering future opportunities to fine tune release. The cytotoxicity of aqueous extracts collected from both films was evaluated on human adult retinal pigment epithelium (ARPE-19) cells using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay with negligible toxicity observed. The results suggest PPy-Dex-P films are highly suitable for the development of electro-responsive implants for the treatment of AMD and DME.

NLRP3 Upregulation in Retinal Pigment Epithelium in Age-Related Macular Degeneration.

Inflammation and oxidative stress are involved in age-related macular degeneration (AMD) and possibly associated with an activation of neuronal apoptosis inhibitor protein/class II transcription activator of the Major Histocompatibility Complex (MHC)/heterokaryon incompatibility/telomerase-associated protein 1, leucine-rich repeat or nucleotide-binding domain, leucine-rich repeat-containing family, and pyrin domain-containing 3 (NLRP3) inflammasome. In the present study, we used a translational approach to address this hypothesis. In patients with AMD, we observed increased mRNA levels of NLRP3, pro-interleukin-1 beta (IL-1β) and pro-IL-18 in AMD lesions of the retinal pigment epithelium (RPE) and photoreceptor. In vitro, a similar increase was evoked by oxidative stress or lipopolysaccharide (LPS) stimulation in the adult retinal pigment epithelium (ARPE-19) cell line, and the increase was reduced in siRNA transfected cells to knockdown NLRP3. Ultrastructural studies of ARPE-19 cells showed a swelling of the cytoplasm, mitochondrial damage, and occurrence of autophagosome-like structures. NLRP3 positive dots were detected within autophagosome-like structures or in the extracellular space. Next, we used a mouse model of AMD, Ccl2/Cx3cr1 double knockout on rd8 background (DKO rd8) to ascertain the in vivo relevance. Ultrastructural studies of the RPE of these mice showed damaged mitochondria, autophagosome-like structures, and cytoplasmic vacuoles, which are reminiscent of the pathology seen in stressed ARPE-19 cells. The data suggest that the NLRP3 inflammasome may contribute in AMD pathogenesis.

Cytoprotective Effect of Polyphenolic Compounds against Oxidative Stress in Cultured Retinal Pigment Epithelial Cells

Purpose: Grape seed-derived polyphenols (GSPs) provide a concentrated source of polyphenols having antioxidant capacity. In this study we investigated the cytoprotective effect of GSP against oxidative stress-induced cell damage in cultured human retinal pigment epithelial (RPE) cells. Methods: Cultured adult retinal pigment epithelium (ARPE)-19 cells were incubated with GSP from Vitis vinifera (0.1, 0.5, 1, 5 or 10 μg/mL) for 24 hours and treated with hydrogen peroxide (H2O2, 0.4 mM) for 24 hours to induce oxidative stress. Cell viability was measured using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Intracellular reactive oxygen species (ROS) was quantified using 2′,7′-dichlorofluorescein diacetate (DCF-DA) fluorescence. Results: The percentage of viable RPE cells was significantly lower in cultures treated with H2O2 0.4 mM than in control cultures. GSP significantly reduced H2O2-induced cell death in a dose dependent manner. GSP at 0.1, 0.5, 1, 5 and 10 μg/mL significantly reduced cell mortality due to the treatment with H2O2. Intracellular ROS production increased significantly in cultures treated with H2O2 0.4 mM compared with control. There was a significant dose-dependent decrease in intracellular ROS levels after treatment of RPE with GSP. Conclusions: GSP, a natural polyphenolic compound, can protect RPE cells from H2O2-induced oxidative stress and reduce intracellular ROS production by scavenging free radicals. This suggests potential effects of polyphenolic compounds against retinal diseases associated with oxidative stress. J Korean Ophthalmol Soc 2016;57(1):106-112

Reduced Expression of Cytoskeletal and Extracellular Matrix Genes in Human Adult Retinal Pigment Epithelium Cells Exposed to Simulated Microgravity

Background/Aims: Microgravity (µg) has adverse effects on the eye of humans in space. The risk of visual impairment is therefore one of the leading health concerns for NASA. The impact of µg on human adult retinal epithelium (ARPE-19) cells is unknown. Methods: In this study we investigated the influence of simulated µg (s-µg; 5 and 10 days (d)), using a Random Positioning Machine (RPM), on ARPE-19 cells. We performed phase-contrast/fluorescent microscopy, qRT-PCR, Western blotting and pathway analysis. Results: Following RPM-exposure a subset of ARPE-19 cells formed multicellular spheroids (MCS), whereas the majority of the cells remained adherent (AD). After 5d, alterations of F-actin and fibronectin were observed which reverted after 10d-exposure, suggesting a time-dependent adaptation to s-µg. Gene expression analysis of 12 genes involved in cell structure, shape, adhesion, migration, and angiogenesis suggested significant changes after a 10d-RPM-exposure. 11 genes were down-regulated in AD and MCS 10d-RPM-samples compared to 1g, whereas FLK1 was up-regulated in 5d- and 10d-RPM-MCS-samples. Similarly, TIMP1 was up-regulated in 5d-RPM-samples, whereas the remaining genes were down-regulated in 5d-RPM-samples. Western blotting revealed similar changes in VEGF, β-actin, laminin and fibronectin of 5d-RPM-samples compared to 10d, whereas different alterations of β-tubulin and vimentin were observed. The pathway analysis showed complementing effects of VEGF and integrin β-1. Conclusions: These findings clearly show that s-µg induces significant alterations in the F-actin-cytoskeleton and cytoskeleton-related proteins of ARPE-19, in addition to changes in cell growth behavior and gene expression patterns involved in cell structure, growth, shape, migration, adhesion and angiogenesis.

Subretinal implantation of human stem cell‐derived RPE on ultrathin carriers in rabbits

SummaryTransplantation of retinal pigment epithelium (RPE) is being developed as a cell replacement therapy for age‐related macular degeneration (AMD). Human embryonic and adult human RPE stem cells (hESC and hRPESC, resp.) are known potential sources that are currently being pursued towards the clinic. Polarized monolayers of SC‐derived RPE were shown to grow on biostable polyester (PET) membranes. They were found to be similar to fetal hRPE monolayers and to have near‐native characteristics. Stamped pieces of RPE monolayers on the carrier were loaded into a custom‐designed surgical instrument and transplanted subretinally in the rabbit, a large‐eyed animal model. Compared to fetal and hRPESC derived RPE, hESC‐RPE xenografts showed better preservation of the neural retina overlying the implant. Histology obtained 4 weeks after implantation confirmed a continuous polarized human RPE monolayer on PET. We demonstrate that the xeno‐RPE monolayer implant survived well and retained its polarization. Moreover, our initial data suggest a distinctly advantageous tolerance of hESC derived RPE xenografts in rabbit subretinal space.

Regulation of ADAM10 and ADAM17 by Sorafenib Inhibits Epithelial-to-Mesenchymal Transition in Epstein-Barr Virus-Infected Retinal Pigment Epithelial Cells.

The a-disintegrin-and-metalloprotease (ADAM) family proteins are widely expressed in the different layers of the retina throughout development. The effect of ADAM proteins on the epithelial-to-mesenchymal transition (EMT) in proliferative vitreoretinopathy (PVR) or AMD is yet to be elucidated. In this study we used Epstein-Barr virus (EBV)-transformed adult retinal pigment epithelial (ARPE) cells to investigate how sorafenib, a multikinase inhibitor, modulates ADAM proteins to control EMT. Epithelial to mesenchymal transition and related mechanisms in EBV-infected ARPE cells were determined by RT-PCR, Western blot, invasion assay, ELISA assay, and gene silencing with siRNA. Mesenchymal-like ARPE/EBV cells exhibited considerably increased cellular migration and invasion compared with ARPE cells and produced EMT-related cytokines. Sorafenib significantly inhibited production of TGF-β1, VEGF, IL-6, IL-8, MCP-1, and TNF-α and blocked the activation of migration-related signaling molecules, such as HIF-1α, p-STAT3, MMP2, and Ang-1. The expression of mature ADAM10, ADAM17, and cleaved Notch 1 proteins in ARPE/EBV cells was downregulated after treatment with sorafenib through the regulatory activity of nardilysin (NRD-1). Gene silencing of NRD-1 in ARPE/EBV cells attenuated secretion of EMT-related cytokines and expression of ADAM10 and 17 and upregulated epithelial markers. Sorafenib controls the mesenchymal characteristics of EBV-infected ARPE cells. Nardilysin and ADAM family proteins might be new targets for the prevention or control of EMT in retinal diseases.

Anthrax lethal toxin suppresses high glucose induced VEGF over secretion through a post-translational mechanism.

To prove anthrax lethal toxin (LeTx) blocks the mitogen activated protein kinases (MAPKs) activation by degrading the MAPK/ERK kinases (MEKs) to suppress vascular endothelial growth factor (VEGF) secretion. Human adult retinal pigmented epithelium (ARPE) cells were cultured and treated with normal glucose, high glucose or high glucose with LeTx for additional 24, 48 or 72h for viable cell count. Total RNA from the ARPE was isolated for reverse transcription polymerase chain reaction (RT-PCR). The conditioned medium of ARPE cells treated in different group for 48h was filtered and diluted to detect the concentration of VEGF by enzyme-linked immunosorbant assays. Evaluate the role of MEK/MAPK pathway in the secretion of VEGF by immunoblotting. In this study, we proved high glucose induced activation of the MAPK extracellular signal-regulated kinase (ERK1/2) and p38 in the ARPE cell line was blocked by anthrax LeTx. LeTx also inhibited high glucose induced ARPE cell over proliferation. LeTx suppressed high glucose induced VEGF over secretion in the ARPE cells, mainly through a post-translational mechanism.

Effects of nicotine on expression of membrane cofactor protein CD46 in human ARPE-19 cells (INC2P.409)

Abstract Age-related macular degeneration (AMD) causes vision loss in humans and its development is often associated with malfunction of the complement system. The complement system is regulated by various proteins including a cofactor protein CD46. Cigarette smoke is a major risk factor for AMD but the impact of nicotine, main component of smoke, on retinal pigment epithelium (RPE) cells is not well studied. We hypothesized that nicotine decreases expression of CD46 in human adult RPE (hARPE-19) cells in vitro. The effects of nicotine were evaluated in two experiments using hARPE-19 cells. In the first experiment, hARPE-19 cells were treated with either 1 µM or 100 µM nicotine. In the second experiment hARPE-19 cells were treated with combinations of 100 µM nicotine and complement depleted or sufficient 10% normal human serum. Western blot and immunofluorescent analyses were used to evaluate the level of CD46 and its cellular localization in hARPE-19. Three isoforms of CD46 occurred in all experimental groups. We suggest that hARPE-19 cells produce full isoform (52 kDa) and two soluble isoforms (38 kDa and 45 kDa). The level of total CD46 and each of the isoforms were similar in all experimental groups. We did not detect any effects of nicotine on the expression of CD46 isoforms with or without active complement system in the medium. Our findings suggest that expression and localization of CD46 on hARPE-19 cells is independent of complement activity, nicotine, or their combination.

Comparative study between amniotic-fluid mesenchymal stem cells and retinal pigmented epithelium (RPE) stem cells ability to differentiate towards RPE cells.

Dysfunction of the retinal pigmented epithelium (RPE) is one of the first effects of dry age-related macular degeneration (AMD) with consequent blindness. Hence, patients affected by this retinal disorder could benefit from a cell-based transplantation strategy for RPE. Actually, an effective protocol to approach this problem is lacking, though recently, it has been postulated the existence of a subpopulation of RPE stem cells (RPESCs) derived from adult RPE and able to reconstitute a functional RPE. On the other hand, the evidence related to the differentiative potential of human mesenchymal stem cells (MSCs) is continuously increasing. Among others, amniotic fluid-derived MSCs (AF-MSCs) may be a promising candidate, since these cells are characterized by high proliferation and differentiative potential. In this study, AF-MSCs and RPESCs were isolated, characterized to assay their stemness and induced to neuronal/retinal differentiation; specific RPE markers were then analyzed. Our results indicate that RPESCs are more suitable candidates for RPE replacement than AF-MSCs.

Protective Effects of Resveratrol against UVA‐induced Damage in ARPE19 Cells

Exposure to solar ultraviolet (UV) radiation is believed to induce the production of reactive oxygen species (ROS) that may cause oxidative stress to retinal pigment epithelial (RPE) cells; oxidative injury to the retinal pigment epithelium has been implicated to play a contributory role in age‐related macular degeneration (AMD). Prior studies have suggested that resveratrol, an abundant and active component of red grapes, can protect several cell types from oxidative stress. This study is to evaluate if resveratrol can protect RPE cells from UVA induced damage, and be useful in the prevention of early AMD. Cell viability of adult RPE cells pretreated with different concentrations of resveratrol was determined using cell viability assay after UVA radiation. Intracellular H2O2 levels were measured by flow cytometry, and UVA induced signaling pathways were detected using Western blotting. Results show that resveratrol inhibited UVA‐induced RPE cell death. The generation of intracellular H2O2 induced by UVA irradiation in RPE cells was suppressed by resveratrol in a concentration‐dependent manner. In addition, resveratrol inhibited the activation of UVA‐induced extracellular signal‐regulated kinase, c‐jun‐NH2 terminal kinase and p38 kinase in RPE cells. There was also a reduction in UVA‐induced cyclooxygenase‐2 (COX‐2) expression in RPE cells treated with resveratrol. This study suggests that resveratrol is effective in preventing UVA‐induced damage in RPE cells and may be suitable for further developments as a chemoprotective factor for the primary prevention of early AMD.

Contribution of membrane trafficking perturbation to retinal toxicity.

The retina is a highly structured tissue that is formed by layers containing 7 different cell types. The photoreceptor cell is a specialized type of neuron in the retina that is capable of absorbing and converting light into electrophysiological signals. There is a constant renewal process for photoreceptors consisting of intermittent shedding of the distal tips of the photosensitive outer segment and subsequent phagocytosis (uptake, degradation and recycling) by retinal pigmented epithelial (RPE) cells. This rebuilding process is essential for vision and the survival of photoreceptors and RPE cells. Drugs with a basic moiety have the potential to accumulate in the lysosome and impair its functions including the phagocytosis process, which could hinder clearance of outer segments and ultimately induce retinopathy. To determine the prevalence of this cellular mechanism in retinal toxicity, a collection of proprietary compounds associated with retinal toxicity were subjected to a battery of in vitro tests using the human adult retinal pigmented epithelium cell line, ARPE-19. The tests included a phagocytosis assay, and lysosomal and autophagosomal staining. The compounds that induced retinopathy clustered in the basic and lipophilic region, which drives lysosomal sequestration. This accumulation coincided with phagocytosis inhibition and an increase in autophagosome staining, suggesting a blockage of the membrane trafficking process. A correlation between the physicochemical properties and in vitro lysosomal pathway effects was established. These data reveal the importance of physicochemical properties of compounds and lysosome accumulation as a potential mechanism for drug-induced retinopathy and demonstrate the usefulness of in vitro screening in predicting this liability.

Protective effects of resveratrol against UVA-induced damage in ARPE19 cells.

Ultraviolet radiation, especially UVA, can penetrate the lens, reach the retina, and induce oxidative stress to retinal pigment epithelial (RPE) cells. Even though it is weakly absorbed by protein and DNA, it may trigger the production of reactive oxygen species (ROS) and generate oxidative injury; oxidative injury to the retinal pigment epithelium has been implicated to play a contributory role in age-related macular degeneration (AMD). Studies showed that resveratrol, an abundant and active component of red grapes, can protect several cell types from oxidative stress. In this study, adult RPE cells being treated with different concentrations of resveratrol were used to evaluate the protective effect of resveratrol on RPE cells against UVA-induced damage. Cell viability assay showed that resveratrol reduced the UVA-induced decrease in RPE cell viability. Through flow cytometry analysis, we found that the generation of intracellular H2O2 induced by UVA irradiation in RPE cells could be suppressed by resveratrol in a concentration-dependent manner. Results of Western blot analysis demonstrated that resveratrol lowered the activation of UVA-induced extracellular signal-regulated kinase, c-jun-NH2 terminal kinase and p38 kinase in RPE cells. In addition, there was also a reduction in UVA-induced cyclooxygenase-2 (COX-2) expression in RPE cells pretreated with resveratrol. Our observations suggest that resveratrol is effective in preventing RPE cells from being damaged by UVA radiation, and is worth considering for further development as a chemoprotective agent for the prevention of early AMD.

Adult human RPE for transplantation: renewing an old promise

Considering the incidence of retinal pigment epithelium (RPE)-related blinding disease will grow to 200 million globally by 2020, the impact of restoring vision by successfully replacing failing or dying RPE is great. In spite of fervent efforts to use primary RPE as a source for transplantation for over 30 years, a clinical therapy has yet to be developed. Due to the progress of pluripotent stem cell technologies and development of RPE differentiation protocols, primary human RPE culture has largely been set aside as a source of RPE for transplantation, as human embryonic stem cell (hESC)- and induced pluripotent stem cell (hiPSC)-derived RPE have become the current popular source for transplantation. Recently, a series of seminal advances in human primary RPE culture has renewed an interest in their potential as a source for RPE transplantation. Primary RPE are better studied and understood than hESC/hiPSC-derived RPE, have an inherent lower risk of tumor formation, and can be Major Histocompatibility Complex (MHC) donor-matched, making them valuable candidates alongside pluripotent stem cells as sources for cell transplantation therapy for RPE-related eye diseases. Keywords: adult stem cell; retinal pigment epithelium; cell transplantation; eye disease (Published: 7 April 2015) Citation: Advances in Regenerative Biology 2015, 2: 27144 - http://dx.doi.org/10.3402/arb.v2.27144

Cholesterol-mediated activation of acid sphingomyelinase disrupts autophagy in the retinal pigment epithelium.

Autophagy is an essential mechanism for clearing damaged organelles and proteins within the cell. As with neurodegenerative diseases, dysfunctional autophagy could contribute to blinding diseases such as macular degeneration. However, precisely how inefficient autophagy promotes retinal damage is unclear. In this study, we investigate innate mechanisms that modulate autophagy in the retinal pigment epithelium (RPE), a key site of insult in macular degeneration. High-speed live imaging of polarized adult primary RPE cells and data from a mouse model of early-onset macular degeneration identify a mechanism by which lipofuscin bisretinoids, visual cycle metabolites that progressively accumulate in the RPE, disrupt autophagy. We demonstrate that bisretinoids trap cholesterol and bis(monoacylglycero)phosphate, an acid sphingomyelinase (ASMase) cofactor, within the RPE. ASMase activation increases cellular ceramide, which promotes tubulin acetylation on stabilized microtubules. Live-imaging data show that autophagosome traffic and autophagic flux are inhibited in RPE with acetylated microtubules. Drugs that remove excess cholesterol or inhibit ASMase reverse this cascade of events and restore autophagosome motility and autophagic flux in the RPE. Because accumulation of lipofuscin bisretinoids and abnormal cholesterol homeostasis are implicated in macular degeneration, our studies suggest that ASMase could be a potential therapeutic target to ensure the efficient autophagy that maintains RPE health.

MiR-184 regulates ezrin, LAMP-1 expression, affects phagocytosis in human retinal pigment epithelium and is downregulated in age-related macular degeneration.

MicroRNA 184 (miR-184) is known to play a key role in neurological development and apoptosis and is highly expressed in mouse brain, mouse corneal epithelium, zebrafish lens and human retinal pigment epithelium (RPE). However, the role of miR-184 in RPE is largely unknown. We investigated the role of miR-184 in RPE and its possible implication in age-related macular degeneration (AMD). Proteomic analysis identified the ezrin (EZR) gene as a target of miR-184 in human RPE. EZR is a membrane cytoskeleton crosslinker that is also known to bind to lysosomal-associated membrane protein 1 (LAMP-1) during the formation of phagocytic vacuoles. In adult retinal pigment epithelium 19 (ARPE19) cells, inhibition of miR-184 resulted in upregulation of EZR mRNA and EZR protein, and induced downregulation of LAMP-1. The inhibition of miR-184 decreased EZR-bound LAMP-1 protein levels and affected phagocytic activity in ARPE19 cells. In primary culture of human RPE isolated from eyes of AMD donors (AMD RPE), miR-184 was significantly downregulated compared with control (normal) RPE. Downregulation of miR-184 was consistent with significantly lower levels of LAMP-1 protein in AMD RPE, and overexpression of MIR-184 in AMD RPE was able to rescue LAMP-1 protein expression to normal levels. Altogether, these observations suggest a novel role for miR-184 in RPE health and support a model proposing that downregulation of miR-184 expression during aging may result in dysregulation of RPE function, contributing to retinal degeneration.

OTX2 mutations cause autosomal dominant pattern dystrophy of the retinal pigment epithelium

PurposeTo identify the genetic cause of autosomal-dominant pattern dystrophy (PD) of the retinal pigment epithelium (RPE) in two families.Methods and resultsTwo families with autosomal-dominant PD were identified. Eight members of...

The newt reprograms mature RPE cells into a unique multipotent state for retinal regeneration.

The reprogramming of retinal pigment epithelium (RPE) cells in the adult newt immediately after retinal injury is an area of active research for the study of retinal disorders and regeneration. We demonstrate here that unlike embryonic/larval retinal regeneration, adult newt RPE cells are not directly reprogrammed into retinal stem/progenitor cells; instead, they are programmed into a unique state of multipotency that is similar to the early optic vesicle (embryo) but preserves certain adult characteristics. These cells then differentiate into two populations from which the prospective-neural retina and -RPE layers are formed with the correct polarity. Furthermore, our findings provide insight into the similarity between these unique multipotent cells in newts and those implicated in retinal disorders, such as proliferative vitreoretinopathy, in humans. These findings provide a foundation for biomedical approaches that aim to induce retinal self-regeneration for the treatment of RPE-mediated retinal disorders.