This won't be the very first test of injecting stem cells in people... back in January it was tested in the spinal cord of an ALS patient.
Even as supporters of human embryonic stem cell research are reeling from last week's sudden cutoff of federal funding, another portentous landmark is quietly approaching: the world's first attempt to carefully test the cells in people.
Scientists are poised to inject cells created from embryonic stem cells into some patients with a progressive form of blindness and others with devastating spinal cord injuries. That's a welcome step for researchers eager to move from the laboratory to the clinic and for patients hoping for cures. But beyond being loathsome to those with moral objections to any research using cells from human embryos, the tests are worrying many proponents: Some argue that the experiments are premature, others question whether they are ethical, and many fear that the trials risk disaster for the field if anything goes awry.
"We desperately need to know how these cells are going to perform in the human setting," said John Gearhart, a stem cell pioneer at the University of Pennsylvania. "But are we transplanting cells that are going to cause tumors? Will they will stay where you put them and do what you want them to do?"
Supporters of these privately funded, government-sanctioned tests, including patients' advocates, bioethicists and officials at the companies sponsoring them, are confident the research has been exhaustively vetted. The Food and Drug Administration has demanded extensive experiments in the laboratory and on animals to provide evidence that the cells are safe enough to test in people and hold great promise.
While Geron Corp. of Menlo Park, California eventually hopes to test the cells on many patients, the first trial will involve 10 partially paralyzed by a spinal cord injury in the previous one to two weeks. Surgeons will inject the first patient with about 2 million "oligodendrocyte progenitor cells," created from embryonic stem cells, in the hopes the cells will form a restorative coating around the damaged spinal cord. In tests in hundreds of rats, partially paralyzed animals walked.
The trial is designed primarily to ensure the cells are safe. But researchers will look for signs that the therapy restores sensation or enables patients to regain movement.
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.
"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."
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