Could a new kind of stem cell repair damage to the retina?

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Rajesh Rao, M.D., Sally Temple, Ph.D., and Jeffrey Stern, M.D., Ph.D., are studying new sources of stem cells.

A newly found source of stem cells at the back of the human eye could lead to a new generation of treatments for blinding retinal diseases. The stunning discovery was reported in 2012 by Sally Temple, Ph.D., and Jeffrey Stern, M.D., Ph.D., internationally known for their work in stem cell research and co-founders of the Neural Stem Cell Institute in Rensselaer, New York.

Rajesh C. Rao, M.D., assistant professor, is among the Kellogg Eye Center scientists who are collaborating with these pioneering researchers to tap the tremendous potential of stem cell-based therapies for eye disease. Dr. Rao, who is also a clinician and surgeon, won an Audacious Research Award from the National Eye Institute last year for his proposal on
reprogramming cells both outside and inside the retina to replace damaged cells.

Drs. Temple and Stern discovered the new source of adult stem cells in the retinal pigment epithelium (RPE), a layer of cells outside the retina. These cells are dormant inside the eye, but once extracted they activate and behave as stem cells, capable of making stable, healthy RPE cells.

A source of healthy cells would go a long way toward cures for diseases like age-related macular degeneration, which is the result of the gradual death of retinal cells.

“We have evidence that these RPE stem cells exist in 90-year-old individuals and even in those with age-related macular degeneration,” says Dr. Temple. “The discovery that the eye retains a previously unrecognized source of stem cells throughout life opens up new avenues for stimulating retinal repair.”

Dr. Rao notes that the discovery of adult stem cells will make the complex task of developing treatments occur more quickly. “Working with adult RPE cells allows us to eliminate many of the steps required to convert other types of stem cells into retinal cells. And we will be better able to control negative effects, such as overproduction of cells, which sometimes create tumors.”

The research team observes that RPE stem cells have great potential for repairing damage to the retina. “The improved safety of our tissue-specific RPE stem cell allows transplantation of progenitor cells rather than mature, fully differentiated progeny,” explains Dr. Stern. “Progenitor states—where cells have not yet committed to a specific function—have the greatest capacity for retinal repair, a finding that has been confirmed in our preclinical experiments.”

Dr. Stern adds that the collaborative teamwork will accelerate therapeutic development. “Working closely with Dr. Rao and others at the Kellogg Eye Center, we are preparing to initiate laying the groundwork for a clinical trial of RPE stem cell therapy for patients with macular degeneration.”

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