Development of Cellular Therapies for Retinal Disease

Age-related macular degeneration (AMD), retinitis pigmentosa (RP) and diabetic retinopathy are leading causes of vision loss and blindness. Because California is the most populous state in the nation, and because the elderly constitute a greater percentage of its population, it is estimated that over 450,000 of Californians will suffer from AMD with severe vision impairment by 2020, leading to huge costs. Diabetes continues to be a major health concern, with vision loss a common outcome. Moreover, the devastating consequences of vision deficits include the progressive loss of independence and productivity, and increased risks of falls, fractures, and depression among diseased population. So this is not only a problem of the individual quality of life, but also an issue of increasing public health burden and concern. Clearly, there is a need for better treatments. In these diseases, loss of vision is due to progressive degeneration of the light sensitive photoreceptor cells of the eye or defects in the supporting cells of the eye, including the retinal pigmented epithelium (RPE). There is now a solid body of evidence that suggests that RPE degeneration is the first step in AMD. There is no cure for these conditions at present, although studies of model experimental animals, mostly rats and mice, suggest several possible routes to therapy. One of these involves the transplantation of cells to slow the degeneration of photoreceptors by replacing key support cells lost during degeneration. My work explores this approach with the object of first identifying and characterizing sources of ocular cells, determining the optimal parameters for transplantation, and identifying molecular and cellular and behavioral events that occur upon transplantation in animal models of retinal degeneration. One source of cells for transplantation is ocular cells derived from human embryonic stem cells (hESC) or induced pluripotent stem cells (iPSC). We have shown that ocular cells, especially RPE, can be derived from both hESC and iPSC, and they can rescue visual function in rodent models of retinal dystrophy. We have shown that RPE can be derived from both hESC and iPSC, and they can rescue visual function in rodent models of retinal dystrophy. We have teamed up with an interdisciplinary disease team of stem cell biologists, materials chemists, neuroscientists, and retinal surgeons to transition this work towards clinical application for AMD, using hESC to produce RPE. Other research aims are to generate specific blood vessel cells from stem cells to replenish the retinal blood vessels in diabetic retinopathy, to generate new photosensitive cells to restore vision, and to use iPSC derived from patients to understand retinal disease and identify novel treatments. California patients with vision loss will benefit greatly from the studies proposed.