Chapter 21 - Sensory Epithelium of the Eye and Ear: Update of Retinal Stem Cell Research 2003 to the Present

Abstract

Mueller glia (MG) are a very promising source of new neurons, as they are distributed throughout the retina and retain the gene expression profile of the retinal progenitor cells (RPCs) that produce all retinal neurons throughout development. This chapter covers the progress made toward the genesis of retinal neurons from embryonic or adult stem cell sources. There have been advances in the understanding of MG as a source of new retinal neurons. Recent studies in fish and mammals have explored the response of MG to the loss of retinal neurons, particularly photoreceptor (PR) cells, and have demonstrated their ability to replace those cells. Manipulation of ES cells to the point where PRs can be made in vitro has been reported. Recent reviews regarding the engraftment of various types of ocular cells for retinal repair have covered the potential and challenges faced by engraftment strategies. MG are among the last generated retinal cell types. Their morphology is similar to that of RPCs and of radial glia that function as progenitor and/or stem cells found elsewhere in the central nervous system. Molecularly, MG have been characterized using two comprehensive gene expression profiling methods: SAGE and microarrays. More important than the in vitro behavior of MG is their ability to divide and produce neurons in vivo. Mammalian MG also appear to participate in limited regeneration. The recent studies of regeneration by MG suggest that the stimulation of MG proliferation is a promising avenue for the development of therapies for the replacement of retinal neurons.