Molecular genetic approaches in the study of retinal progenitor cells and stem cells

Abstract

Understanding how to take advantage of the special nature of multipotential stem cells responsible for renewal of retinal neurons in the mammalian eye could lead to more effective treatment of retinal blindness. The retina develops from precursor cells in the anterior neural plate through a highly conserved histogenic order. The differentiating cells migrate vertically from multipotent retinal progenitor cells in the pseudostratified neuroepithelium to form the inner layer of the optic cup. The differentiation of retinal cell types is promoted or inhibited by a number of secreted factors. Like other lineage systems, the developing retina has a few stem cells and larger numbers of transit-amplifying cells that are more restricted, presumably through neurogenic transcription factors of the bHLH class, including Pax6, Rx 1 , Six3/6, and Lhx2. In the adult, the peripheral rim of the neuroretina of amphibians and fish contribute to growth of the eye throughout adult life. In adult mammals, rare progenitor cells may be found in the pigmented ciliary margin of the eye. Under specific conditions, donor progenitor cells may be incorporated into the adult eye after injection into the subretinal space, but differentiation into functioning retinal neurons has not been achieved. This might be accomplished by the appropriate control of the required transcription factors.