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Stem Cells Restore Sight in Retina-Damaged Mice

Researchers have successfully used mouse embryonic stem cells to replace diseased retinal cells and restore sight in a mouse model of retinitis pigmentosa. This strategy could potentially become a new treatment for retinitis pigmentosa, a leading cause of blindness that affects approximately one in 3,000 to 4,000 people, or a total of 1.5 million people worldwide. The approach also holds promise for the treatment of other retina-damaging diseases. "This research is promising because we successfully turned stem cells into retinal cells, and these retinal cells restored vision in a mouse model of retinitis pigmentosa," said Dr. Stephen Tsang, assistant professor of ophthalmology, pathology, and cell biology at Columbia University Medical Center, and lead author of the paper. "The transplanted cells not only looked like retinal cells, but they functioned like them too." In Dr. Tsang's study, sight was restored in one-fourth of the mice that received the stem cells. However, complications of benign tumors and retinal detachments were seen in some of the mice, so Dr. Tsang and colleagues will optimize techniques to decrease the incidence of these complications in human embryonic stem cells before testing in human patients can begin. "Once the complication issues are addressed, we believe this technique could become a new therapeutic approach for not only retinitis pigmentosa, but age-related macular degeneration, Stargardt disease, and other forms of retinal disease that also feature loss of retinal cells," said Dr. Tsang. Specialized retinal cells called the retinal pigment epithelium help maintain vision. The term retinitis pigmentosa refers to a set of genetic disorders that cause the death of retinal cells on the periphery of the retina, leading to "tunnel vision," where the field of vision is narrowed considerably and everything outside the "tunnel" appears blurred or wavy.

In age-related macular degeneration, retinal cells in the center of the retina degenerate and cause the center part of vision to become blurry or wavy. In 2010, macular degeneration is prevalent in nine million Americans and its incidence is expected to double by 2020. It is estimated that 30 percent of the population will have some form of macular degeneration by the time they reach the age of 75.

Stargardt disease is a genetically inherited juvenile form of macular degeneration that causes progressive vision loss usually to the point of legal blindness.

Replacement of damaged retinal cells in patients with macular degeneration is currently offered in some hospitals, but the therapy is limited by a shortage of donor retinal pigment epithelium cells. By using stem cells and turning them into retinal pigment epithelium cells, the supply is virtually unlimited.

The current research was reported online ahead-of-print in Transplantation. [Press release]