A New Source For Stem Cells?

Congress wasted no time last week jumping on the groundbreaking notion that ordinary adult cells could eventually replace human embryos as the source of stem cells. Opponents of the use of embryos seized on the development to argue that stem cell research could go forward without embryos. And proponents claimed that embryos were needed just as much as ever because of uncertain human applications for the technique.

But the new science didn't change the expected political outcome of the most recent stem cell debate: The House voted 247 to 176 to increase federal funding for embryonic stem cell research. And members pledged to override President Bush's promised veto--although they were unlikely to muster the votes.

"Identical." In the journal Nature, scientists announced that they had successfully converted skin cells of adult mice into the more nascent stem cells, which have enormous medical potential because they can mature into many adult cell types. The modified cells were "identical to embryonic stem cells," said Rudolf Jaenisch, a stem cell biologist at the Massachusetts Institute of Technology. Stem cell expert Arnold Kriegstein of the University of California-San Francisco called it a "huge step forward."

Stem cells have long excited researchers for their potential in treating Parkinson's and other serious diseases. But the research is controversial because it necessitates destroying live embryos. In 2001, Bush issued an order prohibiting federal funding for embryonic stem cell research, limiting financing to existing embryonic lines. The new skin-cell technique, if it works in humans, could provide cells for research without the ethical problems. Still, many scientists consider potential human applications to be years away.

The studies built on work by a Japanese scientist that suggested that just four genes in the skin cells of adult mice, if "turned on" by scientists, could change fully grown skin cells back into stem cells.

The new research, though, has not moved medical use of stem cells any closer to reality, some scientists say. "This only addresses where you get the cells," Kriegstein said. "We already have embryonic stem cell lines that are just as good, if not better."

Researcher Konrad Hochedlinger, a coauthor of the Nature study, cautioned against betting too heavily on the new technique and opposes discarding other stem cell research. "Banning stem cell research now," he said, "would be like prohibiting research on airplanes 150 years ago just because they had developed a car."

Meanwhile, the political spinning continues. Said Sen. John Kerry, chairman of the Senate Subcommittee on Science, Technology, and Innovation: "It'll be used by people who oppose it to argue that there's a better route, and it will be used by others to simply say that you won't have any guarantee where it's going." But, he said, "it's very significant ... and it has the potential to eliminate a lot of controversy from the debate."

By Katherine Leitzell and Chris Wilson