Posted on behalf of Heidi Ledford

Human embryonic stem cells made it one step closer to clinical trials last Friday when the US Food and Drug Administration (FDA) lifted its hold on a study of a stem-cell-derived therapy for severe spinal cord injuries.

It was promising but familiar news to the therapy’s developer, biotechnology firm Geron, headquartered in Menlo Park, California. After Geron filed its famous 21,000-page application to the FDA, the agency put the trial on hold in May 2008. The FDA then informed Geron on 23 January 2009 that the trial was free to proceed, only to freeze it again in August after learning that animals treated with the therapy developed cysts near the site of injury. Geron says the cysts did not harm the animals, and were only observed in one of many animal studies. It has developed new markers and assays to ensure the therapy’s safety.

The FDA’s 30 July announcement that the trial would continue drove Geron’s stock up 18%, after it fell 35% over the previous year. The proposed trial is a safety study in ten patients paralyzed by spinal cord injuries. Human embryonic stem cell-derived glial cells will be injected into their spinal cords within two weeks of the injury. The company is also testing the therapy in animal models of Alzheimer’s disease and multiple sclerosis.

Nature Medicine‘s blog, Spoonful of Medicine, adds that “the FDA’s decision could be good news for Advanced Cell Technology, a stem cell company out of Santa Monica, California that hopes to be next in line to launch an ES cell-based therapeutic trial. The company announced this week that it submitted additional material in support of to its application — first filed in November — for a cell therapy to treat an inherited form of juvenile blindness called Stargardt’s Macular Dystrophy.”