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R. Alper, A. Obolensky, M. Idelson, I. Hemo, R. Yaul, B. Reubinoff, E. Banin; Transplantation of Pigmented RPE-Like Cells Derived From Human Embryonic Stem Cells Provides Functional and Structural Rescue in Dystrophic RCS Rats. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4282.
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© ARVO (1962-2015); The Authors (2016-present)
Replacement and support of dysfunctional Retinal Pigment Epithelium (RPE) may be beneficial in AMD and in subtypes of retinitis pigmentosa. Human Embryonic Stem Cells (hESCs) may serve as an unlimited source for such cells. We examined survival, function and therapeutic potential of pigmented RPE-like cells derived from hESCs in the RCS rat model of retinal degeneration.
Differentiation of hESCs engineered to express eGFP was induced by culturing embryonic bodies (EBs) in suspension for a minimum of 4 weeks. Clusters of pigmented cells within the EBs were mechanically dissected and further cultured. These pigmented cells expressed RPE-specific markers in-vitro and formed "cobble stone"-like arrays upon plating on laminin. A suspension enriched with pigmented cells was injected into the subretinal space of one rat eye. Fellow control eyes were either non-treated or medium-injected. Retinal function was assessed using electroretinography (ERG) 4 weeks after transplantation. Survival and location of the grafts, expression of RPE-specific markers, and thickness of the host photoreceptor layer (ONL)were examined using histological and immunohistochemical techniques.
Dark-adapted (DA) ERG mixed cone-rod responses were significantly better preserved in eyes that received transplants of hESC-derived RPE-like cells. At the highest intensity, mean DA b-wave amplitude in RPE-transplanted eyes was 283.3±37.5µV(n=13) versus 158.5±18.1µV in fellow non-treated control eyes (n=13, p<0.01) and 89.9±14.4µV in medium-injected eyes (n=5, p< 0.01). Large numbers of transplanted pigmented cells were found under the host RPE, in the sub-retinal space and occasionally within the retina and vitreous. These GFP+ cells expressed RPE-specific markers including RPE-65 and Bestrophin as well as the tight junction marker ZO-1. A small precentage expressed the proliferation marker Ki-67. Morphometric analysis of the host retina in vicinity to grafts showed significant preservation of the ONL: thickness of 25.9±3.7µm versus 12.4±2.1µm in areas distant from grafts (p<0.001, n=6).
RPE-like cells derived from hESCs can survive for at least 4 weeks after transplantation into RCS rat eyes, and maintain expression of RPE-specific markers. Transplanted eyes show functional and structural rescue. The results support the potential use of hESC-derived RPE for the treatment of retinal and macular degenerations caused by RPE dysfunction.
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