Stemming blindness: The eyes have it

Medical researchers have high hopes for human embryonic stem cells: There are numerous diseases that might be treated by transplanting cells generated from such stem cells, which have the capacity to mature into a wide variety of specialized tissues. Now, the first report of such an innovation has been published in The Lancet, where the authors detail their successful treatment of age-related macular degeneration (AMD) using cells derived from human embryonic stem cells (hESC).

Macular degeneration is a progressive deterioration of the retinal cells, which destroys a person s sharp, central vision, making it difficult or impossible to read or recognize faces. This damage to the central part of the retina can eventually lead to blindness. And, in fact, the patients involved in this small clinical trial were both legally blind. The two patients, one in her 70s and the other in her 50s, had suffered from severe vision loss as a result of their macular degeneration. This early phase I clinical trial was designed to assess the safety of transplanting hESC-derived retinal tissue beneath the retina of the eyes.

Four months after the procedures, none of the potential complications or adverse effects of such transplantation, had arisen. Even the most typical concern, rejection of the foreign tissue by the body s immune system, was not a problem. Neither patient in this study mounted a significant immune response, most likely because they were treated with low-dose immunosuppressant therapy, and because the retina is relatively protected from an immune response. Also promising was the absence of any kind of tumor or abnormal cell growth in either transplant site. Furthermore, both patients experienced some improvement in their vision.

Given that this early trial has thus far been successful and safe, albeit in only two subjects, researchers hope to attempt treatment of more patients, earlier in the process of macular degeneration, which could bolster the possibility of improving their vision. The study was led by Dr Robert Lanza, Chief Scientific Officer at Advanced Cell Technology in Marlborough, Mass, and Professor Steven Schwartz of the Jules Stein Eye Institute Retina Division at the University of California, Los Angeles.

ACSH s Dr. Gilbert Ross echoes the rest of the medical community in his excitement at this first instance of human embryonic stem cells being used to treat a disease. There is much promise in this method, he says. These patients were essentially blind, and the fact that their vision improved at all, with no evidence of rejection or abnormal growth, is very impressive.