The second clinical trial using human embryonic stem cells has been approved by the U.S. Food and Drug Administration, the company conducting the trial said.

Biotech company Advanced Cell Technology of Marlborough, Mass., said Monday it has received approval for testing retinal cells in patients with Stargardt's macular dystrophy, a rare disease that causes progressive vision loss in children, AAAS ScienceMag.org reported.

The company says it plans to treat 12 patients with advanced cases of the disease with up to 200,000 retinal pigment epithelium cells derived from human embryo stem cells transplanted directly into the eye, Robert Lanza, ACT's chief scientific officer, says.

ACT, which applied for permission for its trial a year ago, is the second company to receive FDA approval for a human embryo stem cell trial.

In October, Geron Corp. and the University of California, Irvine, began the first clinical trial involving embryo stem cells to treat spinal cord injury patients.