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Concept: Retinal pigment epithelium


Age-related macular degeneration (AMD) remains a major cause of blindness, with dysfunction and loss of retinal pigment epithelium (RPE) central to disease progression. We engineered an RPE patch comprising a fully differentiated, human embryonic stem cell (hESC)-derived RPE monolayer on a coated, synthetic basement membrane. We delivered the patch, using a purpose-designed microsurgical tool, into the subretinal space of one eye in each of two patients with severe exudative AMD. Primary endpoints were incidence and severity of adverse events and proportion of subjects with improved best-corrected visual acuity of 15 letters or more. We report successful delivery and survival of the RPE patch by biomicroscopy and optical coherence tomography, and a visual acuity gain of 29 and 21 letters in the two patients, respectively, over 12 months. Only local immunosuppression was used long-term. We also present the preclinical surgical, cell safety and tumorigenicity studies leading to trial approval. This work supports the feasibility and safety of hESC-RPE patch transplantation as a regenerative strategy for AMD.

Concepts: Stem cell, Embryonic stem cell, Retina, Eye, Macular degeneration, Bruch's membrane, Drusen, Retinal pigment epithelium


Age-related Macular Degeneration (AMD) is a leading cause of visual loss among the elderly. A key cell-type involved in AMD, the retinal pigment epithelium expresses a g-protein coupled receptor that, in response to its ligand, L-DOPA, upregulates pigment epithelia derived factor, while downregulating vascular endothelial growth factor. In this study we investigated the potential relationship between L-DOPA and AMD.

Concepts: Signal transduction, Epithelium, Retina, Melanin, Macular degeneration, Bruch's membrane, Drusen, Retinal pigment epithelium


There is an ongoing controversy as to whether major histocompatibility complex (MHC) matching is a solution for allogeneic stem cell transplantation. In the present study, we established retinal pigment epithelial (RPE) cells from induced pluripotent stem cells (iPSCs) in MHC homozygote donors. We observed no rejection signs in iPSC-derived RPE allografts of MHC-matched animal models without immunosuppression, whereas there were immune attacks around the graft and retinal tissue damage in MHC-mismatched models. In an immunohistochemical examination of MHC-mismatched allografts, the transplanted RPE sheets/cells were located in the subretinal space, but the RPE exhibited inflammatory and hypertrophic changes, and many inflammatory cells, e.g., Iba1(+) cells, MHC class II(+) cells, and CD3(+) T cells, invaded the graft area. Conversely, these inflammatory cells poorly infiltrated the area around the transplanted retina if MHC-matched allografts were used. Thus, cells derived from MHC homozygous donors could be used to treat retinal diseases in histocompatible recipients.

Concepts: Stem cell, Stem cells, Cell biology, Major histocompatibility complex, Retina, Organ transplant, Induced pluripotent stem cell, Retinal pigment epithelium


Allografts of retinal pigment epithelial (RPE) cells have been considered for the treatment of ocular diseases. We recently started the transplantation of induced pluripotent stem cell (iPSC)-derived RPE cells for patients with age-related macular degeneration (autogenic grafts). However, there are at least two problems with this approach: (1) high cost, and (2) uselessness for acute patients. To resolve these issues, we established RPE cells from induced iPSCs in HLA homozygote donors. In vitro, human T cells directly recognized allogeneic iPSC-derived RPE cells that expressed HLA class I/II antigens. However, these T cells failed to respond to HLA-A, -B, and -DRB1-matched iPSC-derived RPE cells from HLA homozygous donors. Because of the lack of T cell response to iPSC-derived RPE cells from HLA homozygous donors, we can use these allogeneic iPSC-derived RPE cells in future clinical trials if the recipient and donor are HLA matched.

Concepts: Stem cell, Stem cells, Cell biology, Retina, Organ transplant, Induced pluripotent stem cell, Macular degeneration, Retinal pigment epithelium


This study found evidence of a threshold effect in which the presence of bilateral soft drusen and depigmentation of retinal pigment epithelium was associated with substantially low health-related quality of life (HRQoL) in adult Latinos from the United States.

Concepts: United States, Retina, Eye, California, Macular degeneration, Bruch's membrane, Drusen, Retinal pigment epithelium


We assessed the feasibility of transplanting a sheet of retinal pigment epithelial (RPE) cells differentiated from induced pluripotent stem cells (iPSCs) in a patient with neovascular age-related macular degeneration. The iPSCs were generated from skin fibroblasts obtained from two patients with advanced neovascular age-related macular degeneration and were differentiated into RPE cells. The RPE cells and the iPSCs from which they were derived were subject to extensive testing. A surgery that included the removal of the neovascular membrane and transplantation of the autologous iPSC-derived RPE cell sheet under the retina was performed in one of the patients. At 1 year after surgery, the transplanted sheet remained intact, best corrected visual acuity had not improved or worsened, and cystoid macular edema was present. (Funded by Highway Program for Realization of Regenerative Medicine and others; University Hospital Medical Information Network Clinical Trials Registry [UMIN-CTR] number, UMIN000011929 .).

Concepts: Medicine, Hospital, Stem cell, Retina, Ophthalmology, Induced pluripotent stem cell, Macular degeneration, Retinal pigment epithelium


Mutations in theBEST1gene cause detachment of the retina and degeneration of photoreceptor (PR) cells due to a primary channelopathy in the neighboring retinal pigment epithelium (RPE) cells. The pathophysiology of the interaction between RPE and PR cells preceding the formation of retinal detachment remains not well-understood. Our studies of molecular pathology in the canineBEST1disease model revealed retina-wide abnormalities at the RPE-PR interface associated with defects in the RPE microvillar ensheathment and a cone PR-associated insoluble interphotoreceptor matrix. In vivo imaging demonstrated a retina-wide RPE-PR microdetachment, which contracted with dark adaptation and expanded upon exposure to a moderate intensity of light. SubretinalBEST1gene augmentation therapy using adeno-associated virus 2 reversed not only clinically detectable subretinal lesions but also the diffuse microdetachments. Immunohistochemical analyses showed correction of the structural alterations at the RPE-PR interface in areas withBEST1transgene expression. Successful treatment effects were demonstrated in three different canineBEST1genotypes with vector titers in the 0.1-to-5E11 vector genomes per mL range. Patients with biallelicBEST1mutations exhibited large regions of retinal lamination defects, severe PR sensitivity loss, and slowing of the retinoid cycle. Human translation of canineBEST1gene therapy success in reversal of macro- and microdetachments through restoration of cytoarchitecture at the RPE-PR interface has promise to result in improved visual function and prevent disease progression in patients affected with bestrophinopathies.

Concepts: DNA, Gene, Genetics, Virus, Light, Retina, Eye, Retinal pigment epithelium


The identification of pathways necessary for photoreceptor and retinal pigment epithelium (RPE) function is critical to uncover therapies for blindness. Here we report the discovery of adiponectin receptor 1 (AdipoR1) as a regulator of these cells' functions. Docosahexaenoic acid (DHA) is avidly retained in photoreceptors, while mechanisms controlling DHA uptake and retention are unknown. Thus, we demonstrate that AdipoR1 ablation results in DHA reduction. In situ hybridization reveals photoreceptor and RPE cell AdipoR1 expression, blunted in AdipoR1(-/-) mice. We also find decreased photoreceptor-specific phosphatidylcholine containing very long-chain polyunsaturated fatty acids and severely attenuated electroretinograms. These changes precede progressive photoreceptor degeneration in AdipoR1(-/-) mice. RPE-rich eyecup cultures from AdipoR1(-/-) reveal impaired DHA uptake. AdipoR1 overexpression in RPE cells enhances DHA uptake, whereas AdipoR1 silencing has the opposite effect. These results establish AdipoR1 as a regulatory switch of DHA uptake, retention, conservation and elongation in photoreceptors and RPE, thus preserving photoreceptor cell integrity.

Concepts: Protein, Gene expression, Nutrition, Fatty acids, Essential fatty acid, Retina, Photoreceptor cell, Retinal pigment epithelium


PURPOSE: To investigate the in vitro effect of pH, osmolarity, solvent, and light interaction on currently used and novel dyes to minimize dye-related retinal toxicity. DESIGN: Laboratory investigation. METHODS: Retinal pigment epithelium (RPE) human cells (ARPE-19) were exposed for 10 minutes to different pH solutions (4, 5, 6, 7, 7.5, 8, and 9) and glucose solutions (2.5%, 5.0%, 10%, 20%, 40%, and 50%) with osmolarity from 142 to 2530 mOsm, with and without 0.5 mg/mL trypan blue. R28 cells were also incubated with glucose (150, 310, and 1000 mOsm) and mannitol used as an osmotic control agent in both experiments. Dye-light interaction was assessed by incubating ARPE-19 for 10 minutes with trypan blue, brilliant blue, bromophenol blue, fast green, light green, or indigo carmine (0.05 mg/mL diluted in balanced saline solution) in the presence of high-brightness xenon and mercury vapor light sources. RESULTS: Solutions with nonphysiologic pH, below 7 and above 7.5, proved to be remarkably toxic to RPE cells with or without trypan blue. Also, all glucose solutions were deleterious to RPE (P < .001) even in iso-osmolar range. No harmful effect was found with mannitol solutions. Among the dyes tested, only light green and fast green were toxic to ARPE-19 (P < .001). Light exposure did not increase RPE toxicity either with xenon light or mercury vapor lamp. CONCLUSIONS: Solutions containing glucose as a dye solvent or nonphysiologic pH should be used with care in surgical situations where the RPE is exposed. Light exposure under present assay conditions did not increase the RPE toxicity.

Concepts: Light, Retina, Mercury, Fluorescent lamp, Light pollution, Retinal pigment epithelium, Mercury-vapor lamp, Metal halide lamp


PURPOSE:: To demonstrate outer retinal tubulation (ORT) in various degenerative retinal disorders. METHODS:: This was a retrospective review of the multimodal imaging of 29 eyes of 15 patients with various retinal dystrophies and inflammatory maculopathies manifesting ORT. The morphologic features of ORT and its evolution over time were analyzed using spectral-domain optical coherence tomography data. RESULTS:: Outer retinal tubulation was identified as round or ovoid structures with hyperreflective borders in pattern dystrophy (six eyes), acute zonal occult outer retinopathy (five eyes), retinitis pigmentosa (four eyes), Stargardt disease (four eyes), gyrate atrophy (two eyes), choroideremia (two eyes), and various other degenerative conditions. These structures appeared to develop from the invagination of photoreceptors at the junction of intact and atrophic outer retina. During follow-up, the number and distribution of ORT largely remained stable. As zones of atrophy enlarged, the frequency of ORT appeared to increase. The ORT structures were found in <10% of patients with retinitis pigmentosa, Stargardt disease, or pattern dystrophy. CONCLUSION:: Outer retinal tubulation is found in various degenerative retinal disorders that share in common damage to the outer retina and/or retinal pigment epithelium. The presence of ORT may be an indicator of underlying disease stage and severity.

Concepts: Optics, Retina, Eye, Photoreceptor cell, Ophthalmology, Retinitis pigmentosa, Atrophy, Retinal pigment epithelium