Misidentification of retinal stem cells

Ciliary epithelial cells inside the eye, previously proposed as retinal cell stems, have now been established as being normal adult cells. The misidentification was uncovered by Michael Dyer, PhD and researchers at the St Jude Department of Developmental Neurobiology, USA.

The proposed retinal cells, identified in 2000, were pigmented and Dyer's group became suspicious when they established this as neural stem cells are, in general, and retinal progenitor cells specifically are not pigmented. Dyer explained: "The previous finding was met with a tremendous amount of enthusiasm because of the promise of introducing these cells into the eye to regenerate photoreceptors lost to blindness."

The neuroscientists are now placing emphasis on research which aims at re-engineering stem cells to develop into light-sensitive photorecptor cells, which are lost as a consequence of retinal degeneration.

"This approach would solve many problems of developing cell-based therapy for blindness," Dyer said. "First, these cells are immortal, so they can be grown indefinitely to produce large amounts of cells for treatment. And secondly, they would be immunologically matched to the patient, so there would be no danger of rejection. And thanks to some excellent research during the past 15 years, we know a lot about how to reprogramme such stem cells to make them into photoreceptors."