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Stem Cell Strides Test Bush Policy Scientists Push for Use Of Newer Cell Colonies By Rick Weiss Washington Post Staff Writer Tuesday, April 22, 2003; Page A01 A series of important advances have boosted the potential of human embryonic stem cells to treat heart disease, spinal cord injuries and other ailments, but researchers say they are unable to take advantage of the new techniques under a two-year-old administration policy that requires federally supported scientists to use older colonies of stem cells. Now pressure is building from scientists, patient advocates and members of Congress to loosen the embryo-protecting restrictions imposed by President Bush, with some on Capitol Hill saying they want to take up the issue next month. Stem cells obtained from 5-day-old human embryos can morph into all kinds of human tissues and appear capable of regenerating ailing organs. But while newer and safer versions of the cells have recently been created, the policy imposed by Bush in August 2001 puts those cells off-limits to any scientist whose work is supported with federal money. Supporters of embryo cell research have long grumbled about the Bush policy but have acknowledged that their complaints were largely theoretical because there was still plenty to learn from older cells. The unexpectedly rapid advent of more medically promising cells -- and the possibility of human studies within the next year or so -- have changed that equation, they say, making the Bush policy a real barrier to progress. The older cells allowed under the Bush plan are less attractive researchers because they have been grown in mixtures with mouse tumor cells. The tumor cells, known as "feeder" cells, secrete crucial, though as yet unidentified, nutrients that help nourish human embryo cells. But they can also pass mouse viruses or other microbes to the human stem cells, which means the stem cells could end up sickening patients instead of curing them. Concerned about that risk, the Food and Drug Administration has said it will demand a daunting array of safety tests and long-term patient follow-up for any experiments in which patients are given stem cells that have been in contact with animal feeder cells. Recently, however, scientists have learned how to grow human embryonic stem cells without mouse cells. The new stem cell colonies, or "cell lines," appear ideal for use in clinical trials, scientists say. But they remain unavailable to the vast majority of U.S. stem cell researchers -- most of whom depend on federal grant money -- because the 2001 Bush policy requires those scientists to work only with cells from embryos destroyed before Aug. 9, 2001. The goal was to prevent further destruction of stored human embryos, but it also limits researchers to cell lines tainted by contact with mouse cells. "This is the conundrum we're caught up in as federally funded researchers under the Bush policy," said George Daley, a Harvard University stem cell biologist also affiliated with the Whitehead Institute for Biomedical Research in Cambridge, Mass. "We want to do the basic research that works towards cures, but we cannot use the newly derived, latest and best cell lines, which puts us at a disadvantage." Yesterday, Sen. Arlen Specter (R-Pa.) sent a letter to Bush urging the president to expand the current policy "so that doctors and scientists can use these new safer stem cell lines and realize the promise of stem cell research to cure diseases and disorders that afflict millions of Americans." In interviews last week, Specter and Sen. Tom Harkin (D-Iowa) said they would like to hold a Senate hearing on the topic next month. And Sen. Orrin G. Hatch (R-Utah) said that he is "disappointed at the number of stem cell lines that have been available" to federally funded scientists, and that he will work with others on Capitol Hill "in reexamining the administration's policy." But foes of embryo cell research said they remain opposed to any changes. "We expressed support for the president's policy when he enunciated it, and I don't believe that Congress will overturn it," said Douglas Johnson, legislative director of the National Right to Life Committee. The White House indicated last week it has no intention of changing its position. White House spokesman Scott McClellan said the president's policy was arrived at with "great care" and is based on advice from leading scientists that "existing lines [of stem cells] are more than enough to realize the promise of stem cell research in a way that adheres to the highest ethical standards." The president has said he favors research on "adult stem cells," which are retrieved from adults but which some scientists believe are less versatile than embryonic cells. Under FDA guidelines, doctors will have a difficult time conducting human studies with stem cells grown with mouse cells -- and the agency's concerns go beyond the mere possibility of mouse viruses sickening stem cell recipients. The bigger concern is that a mouse virus could mix its genetic material with human viruses already in the patient, creating a new virus with added virulence and perhaps even a newfound ability to spread from person to person -- much as is believed to have happened with severe acute respiratory syndrome (SARS), which is spreading illness and death around the world. That means stem cell transplants would pose a potential risk not only to the patient but also to close contacts and the public at large. Given those risks, the agency has published a 60-page "guidance" document that spells out the kinds of tests researchers should do if they want permission to give patients human cells that have been in contact with animal cells. First is the need to conduct many different tests aimed at finding any viruses that may be lurking in those cells. But researchers are also instructed to warn patients and their close contacts of the risk of getting an animal disease; monitor the patients' health for the rest of their lives; and save blood and tissue specimens for at least 50 years after each patient dies. Researchers are also urged to get patients to agree to make their medical records available throughout their lives to the FDA, the Centers for Disease Control and Prevention and other public health agencies; agree to be autopsied after death; agree to never donate blood, sperm, eggs or organs; and agree to abide by travel restrictions, medical isolation or other actions that health officials may at some point deem necessary. Clinical scientists and patients have been clamoring for a simpler approach. And lately their wishes have begun to come true. It started last fall, when researchers from Singapore published a landmark report showing that human embryonic stem cells could be maintained in culture dishes if they were accompanied by cells from 14-week-old aborted human fetuses, instead of mouse cells. That granted the cells a reprieve from the FDA's rules. But as the researchers noted in the September 2002 issue of the journal Nature Biotechnology, there remained "ethical concerns" about using cells from aborted fetuses. Then last month scientists at Johns Hopkins University made another leap, showing that human embryonic stem cells could thrive in a culture system containing adult human bone marrow cells, which apparently secrete all the growth factors the stem cells need. The marrow cells offer "a clinically and ethically feasible method to vastly expand human embryonic stem cells on a clinical scale," concluded Linzhao Cheng and his colleagues in the March issue of the journal Stem Cells. Now Cheng and others are scrambling to find other recipes that support stem cell growth. "It's probable that many different human cell types can support the growth of [embryonic stem] cells in the right conditions," Cheng said. "It's certainly broader than we thought." Indeed, Australian researchers say they have learned several ways of growing human embryonic stem cells without animal cells. And Thomas Okarma, president and chief executive of Geron Corp. of Menlo Park, Calif., said his company is close to having an all-human culture system for stem cells. With recent animal studies looking quite positive, he said, he could imagine human clinical tests beginning as soon as a year from now. "That's far ahead of what anyone thought, even us," Okarma said. "So these production issues are going to become important sooner instead of later." But scientists receiving federal grant money are not able to study any of the newly derived lines under the current Bush policy, because they come from embryos that were donated to research after August 2001. (Most come from fertility clinics, which are disposing the embryos at parents' request after successful fertility treatment.) James Battey, who chairs the stem cell task force at the National Institutes of Health -- the primary source of federal funds for stem cell research -- said there is much basic research that scientists can do on the handful of older embryonic stem cell lines and it is premature for scientists to be chafing over the Bush restrictions. The older cells still offer "an enormous research opportunity," Battey said. "We're doing everything we can within what's allowed to move this research agenda forward as quickly as possible." But opponents of the current policy said the United States stands to fall behind other countries with access to more advanced cell lines and more open research policies. "It seems to me it would be foolish for a physician or researcher to use possibly contaminated lines in a patient or research protocol when other lines are available," said Anthony Mazzaschi, associate vice president at the Association of American Medical Colleges. The new advances, he said, "will put a great deal of pressure on Bush's policy." Daniel Perry, a patient advocate who heads the Washington-based Alliance for Aging Research, said patients will demand nothing less than the best cells available. "There's always been an expectation that the [Bush policy] line would have to give way as the science progressed," said Perry, also a vice president for the Coalition for the Advancement of Medical Research, which advocates for stem cell research. "Time is not on our side," Perry said of patients awaiting new therapies, "but the science is." SOURCE: The Washington Post http://www.washingtonpost.com/wp-dyn/articles/A7107-2003Apr21.html * * * ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn