An embryonic stem cell treatment for a rare inherited form of blindness was approved Monday for clinical trials. This is only the second human embryonic stem cell-based trial to be approved by the U.S. Food and Drug Administration (FDA)—the first started last month with a Geron Corp. trial that is assessing the use of such cells to treat spinal cord injuries.

The latest trials will examine the effectiveness of embryonic stem cells to treat Stargardt’s macular dystrophy, which causes the death of photoreceptor cells in the retinal pigment epithelium, often in early adolescence. Some 30,000 to 50,000 people in the U.S. have the disease, for which there is currently no treatment, according to the American Macular Degeneration Foundation.

Advanced Cell Technology, the company that developed the experimental therapy, says it will enroll 12 adults in the phase I/II clinical trial (which tests the methods and doses for safety) and expects to start the research in early 2011. Tests in animals showed that injecting stem cell-derived retinal pigment epithelium cells into the eyes of afflicted rats allowed the animals to regain some of their lost sight.

"It is exciting—a vindication," Robert Lanza, Advanced Cell Technology’s chief medical officer, told Reuters. "All this work really came through," he said, acknowledging that the company had recently been through some difficult financial times.

Federal funding for human embryonic stem cell research remains in question as an appeals court prepares to hear oral arguments early next month about an injunction issued this summer. Meanwhile proponents of the research hope for a legislative move to clarify the current regulations.

"After a decade of intense controversy, the field is finally ready to prove itself," Lanza told The Washington Post. "It also shows the new readiness of the FDA to work with researchers to move exciting new stem cell therapies out of the laboratory and into the clinic."

Photograph by Phineas H., courtesy Flickr