A Harvard University advance in generating embryonic stem cells may have the unintended consequence of hindering congressional efforts to lift research restrictions imposed by President Bush four years ago, leaders on both sides of the issue said yesterday as details of the discovery traveled through the scientific and political communities.
The news that Harvard scientists have successfully converted human skin cells into embryonic stem cells -- without using a human egg or new embryo -- is likely to muddle the already complex debate over federal stem cell research policy.
Even as they were describing the findings being published this week in the journal Science, the researchers cautioned yesterday that the new approach is still in the early stages. They exhorted lawmakers to press ahead with the more conventional, but controversial, technique of removing stem cells from days-old human embryos.
"This technology is not ready for prime time," said lead author Kevin Eggan. "This is not a replacement for the techniques we already have."
Embryonic stem cells hold the promise of treatment or cures for a range of diseases and injuries because they can grow into any type of cell or tissue. However, many conservatives, including Bush, object to the approach because existing methods of extracting the cells involve destroying young embryos called blastocysts.
In August 2001, the president announced he would limit federal research to the cell colonies, or "lines," harvested prior to that date.
In May, the House passed legislation that would ease the Bush restrictions and allow government-funded research on tens of thousands of cell lines taken from frozen embryos donated by couples who have completed fertility treatments. Senate Majority Leader Bill Frist (R-Tenn.) recently reversed himself and announced he supports the bill, raising hopes it will be acted on this fall.
The Harvard discovery complicates the Senate prospects because it offers the tantalizing, albeit distant, prospect of creating genetically tailored hybrid cells without destroying new embryos. The technique used laboratory-grown human embryonic stem cells to "reprogram" the genes in a person's skin cell, turning that skin cell into an embryonic stem cell. In the future, scientists hope to begin the process with an adult cell and convert it into an embryonic cell before fusing it.
"All this is confirmation we will see breakthroughs without compromising ethical standards," said Sen. Tom Coburn (R-Okla.), a physician who has led opposition to embryonic stem cell research. "We're not going to have to go that way if we can just be patient and fund the basic science."
On the other side, Rep. Michael N. Castle (R-Del.) conceded that the latest breakthrough will make his effort to lift the Bush limits more challenging.
"I consider this a point well struck for them," he said. "For those who just wish to oppose any use of embryonic stem cell research at all, they will say, 'Here are Harvard scientists saying this can be done.' "
Castle and others stressed, however, that for now the new Harvard procedure requires cell lines taken from a human embryo.
"It's not as if this research says there is no need for embryonic stem cells," said Sean Tipton, spokesman for the American Society for Reproductive Medicine. "It continues to show the enormous potential of stem cell research and highlights the value of embryonic stem cells as a source of research material."
When it returns next month, the Senate could face as many as a half-dozen competing bills, including one that shifts tax money to alternative forms of research and one that bans research known as "therapeutic cloning."
Each bill has the potential to siphon support away from the Castle legislation lifting the Bush restrictions.
For lawmakers "who want to appear to support embryonic stem cell research without alienating their conservative base, it gives them something they can vote for even if it continues to trade patient interests for political symbolism," said R. Alta Charo, a professor at the University of Wisconsin medical and law schools.
"If this new avenue is useful, that's wonderful, but it would be a colossal mistake for any member of the United States Congress to pretend he or she knows enough about this process to foreclose any other process," said James C. Greenwood, president of the Biotechnology Industry Organization. "We don't think the public should allow the politicians to hide behind such thin fig leafs."