Abstract
Cells can be reprogrammed to assume a different fate in vitro. Oct3/4, Sox2, and Klf4 have been used to direct cells to a pluripotent state. These induced pluripotent stem (iPS) cells, which are able to differentiate into any cell type, may provide a novel the-rapeutic avenue for a wide range of disorders. Photoreceptors or retinal pigment epithelia derived from patient iPS cells, for example, may be useful in transplantation therapy for retinal degenerative diseases, and in vitro disease models and drug screening. Recent evidence, however, has revealed significant differences between embryonic stem (ES) cells and iPS cells. iPS cells have helped elucidate the underpinnings of pluripotency, in particular similarities and differences among mouse ES cells, human ES cells, and epiblast stem cells. Intriguingly, cellular plasticity suggests that a specific set of factors could potentially convert somatic cells directly to retinal progenitors or retinal cells. Cellular reprogramming methodologies should markedly contribute to both our understanding of retinal degenerative diseases and the development of novel therapies, including cell transplantation and new drugs.
