Scientists in California have begun selecting patients to participate in the second research project approved in the United States to evaluate a therapy made from human embryonic stem cells.

A team led by Steven Schwartz at UCLA started picking volunteers for the studies, which will treat two forms of progressive blindness, Advanced Cell Technology of Marlborough, Mass., which is sponsoring the study, announced Thursday.

The Food and Drug Administration in November approved the company’s plans to test cells created from human embryonic stem cells on patients suffering from Stargardt Macular Dystrophy, a progressive form of blindness that usually begins in childhood, and Dry Age-Related Macular Degeneration, the leading cause of blindness in the developed world.

Twelve patients suffering from each condition will undergo a procedure in which 50,000 to 200,000 retinal pigmented epithelial cells will be injected into their eyes. Researchers hope the cells, which have been created from human embryonic stem cells, will replace those ravaged by the diseases. Both studies are designed primarily to test for safety, but researchers will evaluate the subjects for signs the cells may be helping their vision. In rats, the cells helped prevent further vision loss and restored some sight.

The research team has selected for further testing about five people from among about 30 or 40 who volunteered, Schwartz said in a telephone interview. The first patients could be treated within the next few months, he said.

After many delays, the first FDA-approved experiment in people of human embryonic stem cell therapy began in October, when doctors in Atlanta injected millions of cells into the spine T.J. Atchison, 21, of Chatom, Ala. Atchison had been partially paralyzed in a car accident less than two weeks earlier. Although that study also is aimed mostly at assessing the therapy’s safety, researchers are checking to see whether the cells restore any feeling or movement. A second patient was subsequently treated at Northwestern Memorial Hospital in Chicago. The only results released by the study’s sponsor, Geron of Menlo Park, Calif., indicate that neither patient has suffered any significant adverse effects.

Human embryonic stem cell research is highly controversial. Many scientists think the cells may revolutionize medicine by leading to new treatments for many diseases. But days-old embryos have been destroyed to obtain the cells, which some critics consider immoral. And some proponents worry about whether the approach is safe and has been adequately vetted before being tried in people.