Scientists may be closing in on a remedy for a common degenerative condition of the retina called retinitis pigmentosa.

In mice that develop the disease, stem cells - “master” cells that can become many different kinds of tissue - injected into the eye prevented degeneration of blood vessels in the retina, a California research team reports. As a result, some vision was preserved.

Ultimately, it may be possible give people stem cells taken from their own bone marrow “and delay retinal degeneration with concomitant loss of vision,” Dr. Martin Friedlander and colleagues suggest in the Journal of Clinical Investigation.

Friedlander, at the Scripps Research Institute in La Jolla, and his team experimented with mice that develop two types of complete retinal degeneration within 16 days of being born. Injection of stem cells before that happened maintained normal appearing blood vessels, in both types of mice.

Moreover, Friedlander’s group saw that the light receptors called cone cells were preserved, an effect that lasted for as long as 6 months.

The researchers were able to detect electrical signals from the retina in treated animals, but not in untreated mice. While conceding that the signals were not as strong as normal, the investigators maintain that “even such minimal signs of electrical function in the retina may be sufficient to support vision.”

They conclude that this approach “may be useful in the treatment of currently untreatable blinding disease.”

However, warns Dr. Lois E. H. Smith, of Children’s Hospital in Boston, in a related commentary, “There are many questions and much work that lies between the current study and clinical application.”

Even so, she adds, “It is not necessary to answer all of them before proceeding further with this new approach to preventing cone loss in retinitis pigmentosa.”

SOURCE: Journal of Clinical Investigation, September 2004.