Study shows hope for macular degeneration
A recent study conducted on blind mice at Columbia University Medical Center indicates that treatment to prevent or reverse macular degeneration and other causes of blindness in humans may be available in the near future.
Researchers used human skin cells and genetically altered them to become retinal cells. Called induced pluripotent stem (iPS) cells, they come from a living donor's own skin. Theoretically, IPS cells could be secured, altered and then injected back into the same person, which would eliminate the need for anti-rejection medications.
"No mice rejected the transplanted cells during the study, and no tumors were found," said Stephen Tsang, MD, PhD, associate professor of ophthalmology at Columbia University Medical Center and the lead researcher of the study. Tumor growth has been a concern in cell transplantation.
In the study, most of the 34 mice who received injections of the iPS retinal cells experienced improvement in their vision, and the improvement lasted throughout their lives. In contrast, none of the mice who received injections of saline or inactive cells showed any improvement in vision.
The study shows great promise for treatment of people who become blind through macular degeneration, one of the leading causes of blindness in people age 60 and older. It's estimated that over 10 million Americans have macular degeneration, according to the American Macular Degeneration Foundation.
In macular degeneration, a person's central, sharp vision deteriorates. It isn't known for sure whether the iPS cells could be used to prevent macular degeneration or to reverse it. Doctors are able to determine now which patients are most at risk for macular degeneration, however, so it is likely that iPS cells could prevent some of these from developing further.
iPS cells could also be used to treat retinitis pigmentosa, an eye disease which is the leading cause of blindness in people with diabetes.
"We are still in the early stages of using iPS cells derived from human skin," said Tsang. "Safety is the first consideration." Risks of the procedure include retinal detachment and infection, which could make vision worse.
In the study, skin was taken from the donor's back, though it could be taken from any part of the body. The back was chosen because the lesion would be less noticeable.
The eye is an ideal site for studying the use of iPS cells, said Tsang, because the eye is easily accessible. Transplanting cells into the eye is not invasive and, after transplantation, it can be examined daily for changes.
More studies need to be conducted on animals before human trials can begin. Tsang hopes to start human studies within three years.
"This is really the future of personalized medicine," said Tsang. In the future we could even have skin matching banks, said Tsang, much the way we have blood and bone marrow registries now.
For more information go to www.cumc.columbia.edu/news-room/2012/09/13/stem-cells-improve-visual-function-in-blind-mice/#.UGxGl03A8ud.