Stem Cells

This chapter explores a different perspective of retinal disease treatment, using stem cells and their derived tissues to avoid blindness. The goal of stem cell therapy is to replace the damaged cells (pluripotent stem cells) or repair the damaged tissue via paracrine effects (multipoint stem cells). Human embryonic stem cells (hESCs) are pluripotent cells taken from the cells of the blastocyst and can differentiate into all three germ cell layers. For this reason, hESCs can develop into all somatic cell types, including all types of retinal cells. Human-induced pluripotent stem cells (hiPSCs) are generated from adult somatic cells and genetically reprogrammed into other adult cells through transcription factors. They have the advantage of enhancing immune tolerance because they are derived from a patient’s own cells compared to cells derived from allogenic hESCs, which require immune suppression. RPE dysfunction plays a critical role in mediating several disease processes. Stem cells-derived RPE cells have structural and functional elements similar to native RPE cells and express distinctive genes required for critical RPE functions, such as RPE65, BEST1, VDP, and GULP1. With the hope of modifying evolution of RPE disorders, they have already been used in human clinical trials in disorders like age-related macular degeneration and Stargardt disease. Experimental models have shown the ability to differentiate stem cells into photoreceptors, with the formation of synapses, improvement in visual function, and regeneration of photoreceptors in animals. These studies provide progress toward the eventual goal of restoring and protecting vision from retinal degenerative diseases and congenital causes of blindness. Despite promising results, only time will tell whether the efficacy of cellular therapies will come to fruition.