Selling Out for Science; Research: The shrill debate over stem cells in the United States has forced some scientists to hype their potential for cures.

Byline: Fred Guterl (With Jaime Cunningham, Joan Raymond and Ginanne Brownell)

By the time Californians go to the polls this week, they will have endured months of Biology 101 lectures from celebrity activists such as eBay founder Pierre Omidyar and producer Doug Wick. Seeing Hollywood and Silicon Valley types pushing their favorite causes--in this case, Proposition 71, a $3 billion research initiative for human embryonic stem cells--is nothing new in California. Seeing scientists do so is another matter. Hans Kierstead of the University of California's Reeve-Irvine Research Center announced shortly before Election Day that he had succeeded in coaxing human embryonic stem cells into producing highly purified brain cells called oligodendrocytes, then injected them into rodents with bruised spines. After nine weeks, the rats regained their ability to walk and run. The results were "thrilling and humbling," said Kierstead. "The humbling part is that the cells are so incredibly powerful."

A decade ago not one person in a million had heard of stem cells. Most people probably still don't know what stems cells are, but they know that the cells are special, and that they hold the power to cure some of the most intractable human diseases. All this is true--with the proper caveats. Scientists are usually the ones pointing them out, but not in the highly politicized atmosphere of stem-cell research. Aside from the ethical questions--should we tamper with embryonic cells, or perform nonreproductive human cloning?--there are more utilitarian ones: Will stem cells deliver? Is the public being sold a bill of goods? Scientists acknowledge the challenges but also tend to be incorrigibly upbeat. It's hard to tell if they're being seduced by their own rhetoric.

Judging from the hype in the run-up to Proposition 71, you might think that the chief obstacles to turning stem cells into cures were political. But the technical ones are ...