WASHINGTON — Fresh from a talk with a California researcher who has moved to England because of U.S. restrictions on his work, Sen. Barbara Boxer appealed to President Bush Thursday to loosen his recent restriction on stem-cell studies.
In a letter to Bush, Boxer said his decision could force scientists to work with cells unfit for treating humans.
After talking with Dr. Roger Pedersen, a researcher at the University of California at San Francisco who has since left for Cambridge University in England, Boxer also told Bush that other top scientists might follow Pedersen abroad.
"I fear that the uncertainty surrounding federal support for stem-cell research will lead other researchers to leave our country as well," the California Democrat wrote.
After her session with Pedersen, Boxer said she was convinced the narrow framework Bush has provided for research could lead to a scientific dead end. Bush limited federal funding for future research to stem-cell groupings called "lines" that existed before Aug. 9, the date of his decision.
Bush estimated 60 such cell lines existed, although scientists have disputed the figure as too high. Stem cells taken from human embryos can potentially be developed to repair damage caused by Parkinson's disease, strokes and other maladies.
Boxer said she had learned from Pedersen that the embryonic cell lines used mouse cells to provide nutrients and some were exposed to extracts from cow's blood. Pedersen fears that if the Bush-permitted stem cells were ever transplanted into humans in an effort to treat disease, they would be rejected or could cause other complications, Boxer said.
"It is essential that more stem-cell lines be derived without using animal products," Boxer wrote to Bush.
"Unless a miracle happens, we're stuck with the president's decision," she conceded Thursday.
Bush deliberated on his decision for months before announcing it. He said he was balancing the need for further medical research with his concern that more embryos not be destroyed.
Some scientists and anti-abortion advocates praised Bush for his decision, which he called a compromise. They say he provided a basis for continued research into diseases, while preventing the destruction of any more embryos, even those discarded in fertility clinics.
But other researchers, and many in Congress like Boxer, say he has hamstrung research.
"The small number of stem cell lines available under the president's directive do not represent the diversity of the population and may not be sufficient to prevent rejection in patients," she said.
In an interview with the Chronicle just a day after Bush disclosed his policy, Pedersen wouldn't say for sure whether he was going to carry out his plan to leave San Francisco.
However, he is now in England, at his lab in Cambridge. He has maintained a research affiliation with UCSF.
In an article he published last week in the Financial Times newspaper, the researcher said, "The potential benefits of stem cell research promise to transform health care and stimulate economic growth. But they will accrue to countries where the policies and funding encourage, rather than hobble, the stem cell enterprise."