Yes, it's a milestone. The first federally approved trial of an embryonic stem cell therapy has begun, and the first patient with a spinal cord injury has been injected with a treatment made from embryonic stem cells. But if all goes well with the trial, conducted by the biotech company Geron, there won't be any dramatic results--the trial is simply intended to test the treatment's safety, and patients will receive very low doses of the stem cell concoction.