Generation of induced pluripotent stem cells (iPSCs) from human somatic cells was perhaps the most seminal translational discovery of the last decade. It opened new ways to study disease mechanisms in vitro and to discover druggable targets for potential therapeutic interventions. In addition, it provided an independent approach for a cell-based therapy. Several differentiated cell types and tissues have so far been derived from these induced stem cells including two critical cell types of the eye the retinal pigment epithelium (RPE) and the photoreceptors. Based on our experience with the structure and functioning of primary human RPE we sought to determine the RPE-like features of these pigmented epithelial cells derived from iPSCs. To this aim, we have generated ten control iPS cell lines in collaboration with Sally Temple/NYNSCI. These include - lines generated from genetically matched but epigenetically distinct fetal ocular tissue (RPE, sclera, cornea), lines derived from adult ocular tissue (RPE, sclera), and adult fibroblasts. These iPS cell lines were characterized for their pluripotency and differentiated towards RPE-lineage. Currently, we are characterizing these lines for their RPE-character. In preliminary experiments, we have determined that iPSC-derived RPE-like cells express several key RPE-markers, show robust electrical responses to changing potassium concentration at the apical side, show polarized secretion of cytokines towards the apical and the basal side, and show differential permeability of the apical membrane to CO2. These findings are very similar to what we have observed using primary human fetal RPE. At completion, this work will provide a collection of well-characterized control iPS cell lines and assays (molecular and physiological) that can be used to define RPE cells generated from stem cells. It will also provide the basis for developing iPSC-derived RPE for cell-based therapy and for the analysis of RPE cells derived from iPSCs of patients with retinal degenerations.
|Bharti, Kapil; Miller, Sheldon S; Arnheiter, Heinz (2011) The new paradigm: retinal pigment epithelium cells generated from embryonic or induced pluripotent stem cells. Pigment Cell Melanoma Res 24:21-34|