From the May 2011 Issue of Stem Cells
Paper Commentary by Carla Mellough
Complimentary to another article involving the retina, also featured in the May edition of Stem Cells, the potential for induced pluripotent stem cells (iPSC) to generate replacement retinal components is further demonstrated in an article by Kokkinaki et al. from Georgetown University in Washington DC, which reports that iPSCs can be differentiated into retinal pigmented epithelium (RPE) that can perform many of the normal functions of native RPE. The health of the light sensitive photoreceptors that reside at the back of the retina are dependent on a functional RPE, in fact the two cell types are interdependent. Within the eye, the apical membrane of the RPE cells face the outer segments of the photoreceptors and not only phagocytose shed photoreceptor outer segments but perform a number of other functions including the release of growth factors and isomerisation of retinal from the phototransduction cycle. Various forms of retinal disease require the replacement of dysfunctional RPE with new functional RPE, such as age-related macular degeneration (AMD), where impaired RPE function in turn causes the death of macular photoreceptors. Many reports have shown the facile generation of RPE from both human embryonic stem cells (hESC) and induced pluripotent stem cells (RPE), making these cell types an attractive source of replacement RPE.