Human tests set for stem cells

Spinal cord injuries, however, are highly unpredictable and in many ways mysterious. Patients can often improve on their own, for example, which will make it difficult to evaluate whether the cells had any effect. Some wonder whether trauma victims who have so recently suffered a life-altering injury will agree to the experiments out of desperation without fully grasping the risks.

"Think of it this way: You are a healthy young person, you have had a terrible accident, you wake up in the hospital and are told that you will never walk again, that you will paralyzed for the rest of your life," Stanford University bioethicist David Magnus wrote in an e-mail. "Then you are told that there is a Phase I stem cell clinical trial that you are eligible for, but a decision needs to be made quickly. It would be hard to imagine that would be the optimal scenario from the point of view of informed consent."

In the meantime, officials at Advanced Cell Technology of Menlo Park, Calif., are hoping for the FDA's go-ahead to start possibly even sooner injecting 50,000 to 200,000 cells into the eyes of 12 patients suffering from Stargardt's macular dystrophy. Retinal pigmented epithelial cells, also made from human embryonic stem cells, should replace those ravaged by the progressive loss of eyesight, usually beginning in childhood. Studies in rats found the cells helped prevent further vision loss and even restored some sight. The company hopes the approach will work for many conditions, including the leading cause of blindness among the elderly.

"These diseases are devastating," said Robert Lanza, Advanced Cell Technology's chief scientific officer. "If we could make a difference, it would be profoundly important."

Christopher Goodrich, 55, of Portland, Ore., whose eyes started failing at age 7 and who now sees the world as if looking through a dense fog, hopes he will be one of the first patients.

"The thought of being able to regain some of my vision - to be able to go back to work, to ride a bike, to even be able to see the moon - would just be so awesome," Goodrich said.

But safety worries linger for both studies. Patients risk making their conditions worse - perhaps becoming fully paralyzed or losing whatever vision they have left.

"It's one thing if you are doing a treatment for a disease where the patient is going to die without treatment," Magnus said. "It's another if they could have a relatively good functioning life."

Okarma and Lanza said they are confident the therapies are safe. Only patients 18 or older will be initially considered for the eye study, and the treatment will only be administered to one eye to ensure the patients retain at least some vision in a worst-case scenario, Lanza said. Even if there are problems with the victims of spinal cord damage, Geron's research shows the cells do not leave the site of the injury, indicating patients would not suffer any ill effects, Okarma said. Extra precautions, including assigning each subject an independent advocate, will guarantee that volunteers fully understand their decisions, he said.

"If human embryonic stem cells are going to be useful in treating humans, someone has to be the first one to try it," said Hank Greely, a Stanford lawyer and bioethicist. "They need to have their fingers crossed and hold their lucky rabbit's foot and be really careful in their preparations, because before you try something in humans you never know what's going to happen."