April 1, 2009

Some eye cells misidentified as stem cells

A U.S.-led team of medical researchers says cells isolated from the eye that many scientists believe are retinal stem cells are actually normal adult cells.

The international study, led by Michael Dyer of St. Jude Children's Research Hospital, suggests therapies to restore vision in people with retinal degeneration should emphasize the use of other types of stem cells.

Stem cells are immature cells capable of producing large numbers of adult cells, such as retinal cells, the researchers said. Scientists say they believe stem cells offer the promise of regenerating damaged tissue in organs such as the eye, brain and heart.

The new findings suggest research on cell therapies to restore blindness shouldn't concentrate on eye cells previously believed to be retinal stem cells. More promising, the scientists said, is research aimed at re-engineering stem cells to develop into the light-sensitive photoreceptor cells that are lost as a result of retinal degeneration.

The study, which included Samantha Cicero, Sharon Frase, Samuel Connell, Lionel Chow, Suzanne Baker and Brian Sorrentino of St. Jude; Dianna Johnson of the University of Tennessee Health Sciences Center; and Steve Reyntjens from the FEI Helios Nanolab in the Netherlands, appears in the early online edition of the Proceedings of the National Academy of Sciences.