Stem cells for retinal repair

Abstract

Remarkable progress over the past decade has led to the first clinical studies of stem cell therapy for retinal disease. The unique access retina offers for implantation, monitoring, and ablation is well suited for stem cell trials, and retinal applications have now moved to the forefront of the field of regenerative medicine. Retinal progeny derived from either pluripotent stem cells or tissue-specific retinal and retinal pigment epithelium (RPE) stem cells have the capacity both to replace damaged retina and to provide trophic support that slows disease progression. In contrast, bone marrow and neural stem cells produce nonretinal progeny that provide trophic support but with limited integration and capacity to differentiate into retinal progeny that can replace damaged retinal tissue. Embryonic and induced pluripotent stem cells differentiated into neural retinal and RPE progeny provide an unlimited supply of human cells for transplantation and disease modeling but raise the risks of aberrant differentiation and over proliferation. Tissue-specific stem cells isolated from neural retina or RPE that are naturally committed to retinal fates have a restricted lineage potential that improves the margin of safety. This improved safety of retina and RPE stem cells is balanced, however, by a restricted proliferative potential, which limits the quantity of progeny produced. In this chapter, we review the types of stem cells under development for retinal therapy.