When there's nothing else to prescribe, hope works like a drug. A quadriplegic patient tells herself it's not a matter of if they find a cure but when. Who's to say whether salvation is still 10 or 15 years away? After all, researchers have been injecting stem cells into paralyzed rats and watching their spinal cords mend. "Stem cells have already cured paralysis in animals," declared Christopher Reeve in a commercial he filmed a week before he died.
But what is the correct dose of hope when the diseases are dreadful and the prospects of cure distant? Last month, when President George W. Bush vetoed the bill that would have expanded funding for human embryonic-stem-cell (ESC) research, doctors got calls from patients with Parkinson's disease saying they weren't sure they could hang on for another year or two. The doctors could only reply that in the best-case scenario, cures are at least a decade away, that hope is no substitute for evidence, that stem-cell science is still in its infancy.
It is the nature of science to mix hope with hedging. It is the nature of politics to overpromise and mop up later. But the politics of stem-cell science is different. Opponents of ESC research--starting with Bush--argue that you can't destroy life in order to save it; supporters argue that an eight-cell embryo doesn't count as a human life in the first place--not when compared with the life it could help save. Opponents say the promise of embryo research has been oversold, and they point to the cures that have been derived from adult stem cells from bone marrow and umbilical cords; supporters retort that adult stem cells are still of limited use, and to fully realize their potential we would need to know more about how they operate--which we can learn only from studying leftover fertility-clinic embryos that would otherwise be thrown away.
Back and forth it goes, the politics driving the science, the science pushing back. Stem-cell research has joined global warming and evolution science as fields in which the very facts are put to a vote, a public spectacle in which data wrestle dogma. Scientists who are having surprising success with adult stem cells find their progress being used by activists to argue that embryo research is not just immoral but also unnecessary. But to those in the field, the only answer is to press ahead on all fronts. "There are camps for adult stem cells and embryonic stem cells," says Douglas Melton, a co-director of the Harvard Stem Cell Institute. "But these camps only exist in the political arena. There is no disagreement among scientists over the need to aggressively pursue both in order to solve important medical problems."