Stem Cells Hold Promise for Eye Diseases
Help correct vessel damage in mice, study says
TUESDAY, July 30, 2002 (HealthDayNews) -- Stem cells taken from adult bone marrow may hold the key to a treatment for diabetic retinopathy and other eye diseases.
Preliminary research conducted at Scripps Research Institute in California has found that stem cells taken from the bone marrow of mice halted vessel damage in the animals' eyes. The research appears in the September issue of Nature Medicine.
"It's a very promising study, and it illustrates the wide range of utility of stem cell treatment in a variety of diseases," says Dr. Fouad Kandeel, director of the department of diabetes, endocrinology and metabolism at City of Hope National Medical Center in Los Angeles.
Diabetic retinopathy and age-related macular degeneration are the leading causes of vision loss in the industrialized world. Both result from problems with the blood vessels serving the retina. Diabetic retinopathy is the leading cause of blindness among working-age Americans.
For the study, the researchers first injected stem cells taken from the bone marrow of adult mice directly into the eyes of the mice and found that the stem cells targeted astrocytes, cells that are usually, if not always, associated with injury response.
Once the stem cells hooked onto the astrocytes, they incorporated into blood vessels that were in the process of developing -- not vessels that were already established.
"If the blood vessels are destined to deteriorate, the stem cells will completely reverse and stabilize the problem," says Dr. Martin Friedlander, the senior author of the study, who is chief of the retina service at Scripps Clinic in La Jolla, Calif. "That was really a surprise -- a real pleasant, interesting surprise."
The finding has several potentially exciting implications, Friedlander adds.
In the case of diabetic retinopathy, for instance, the main problem is that the eyes don't get enough oxygen because blood vessels develop abnormally. One of the only treatments now is to actually destroy part of the retina with a laser so the eye needs less oxygen.
"It works in about half of the patients and it's better than nothing," Friedlander says. He adds that he nevertheless cringes whenever he has to perform this procedure.
An alternative might be to administer a compound that inhibits the growth of blood vessels, but this might shut down all new blood vessels, rather than just the abnormal ones. Several drugs that employ this method are being tested in clinical trials.
"It makes more sense if we can take abnormal new vessels and coax them into becoming stable new vessels," Friedlander says. "We have not done this, not even in diabetic mice, but it has the potential to rescue abnormal blood vessels."
Yet another possibility is to use gene therapy to deliver an anti-angiogenic factor (something that inhibits the growth of new blood vessels) so as to prevent the formation of new abnormal vessels without affecting the old ones.
One advantage of this method -- if it pans out in future studies -- is that doctors can use genes from the patient rather than introduce foreign cells, which run the risk of being rejected.
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