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 that 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.
"We're very optimistic," said Thomas B. Okarma, president and chief executive of Geron Corp. of Menlo Park, Calif., which after years of delay received a green light in July from the FDA to study patients partially paralyzed by spinal cord injuries. "If we're right, we'll revolutionize the treatment of many chronic diseases."