Stem Cell Research May Be Hindered by Mouse Cells
"Most or all" of the 60 embryonic stem cell lines approved for federally funded research were created using "feeder" cells from mouse embryos, a fact that may prove to be a "substantial hurdl[e]" for stem cell research because of "stringent" FDA rules governing the use of animal products in humans, the Washington Post reports. Once stem cells are extracted from human embryos, they are placed with embryonic mouse "feeder" cells, which "excrete some unknown nutrient or growth factor that helps the human cells stay healthy." Under FDA regulations, the cells would be considered "xenotransplants," transplants containing animal tissue, and would be subject to greater scrutiny. Those developing stem cell-based therapies would have to conduct more research and document all of their efforts to prove that the therapies do not carry the risk of transferring an animal virus to humans. Further, under the FDA rules, some groups of patients for whom alternative therapies exist, such as those with juvenile diabetes, would not be eligible to take part in stem cell trials. Although several companies are working to develop ways of maintaining human embryonic stem cells without the use of the mouse cells, it is not clear if any of the stem cell lines approved for federally funded research were derived with those new methods. Only one company, Geron Corp., has claimed to have developed an alternative to the mouse cells, but CFO David Greenwood "declined to say" whether the company had developed any cell lines using the technology prior to Aug. 9, when President Bush made his announcement to limit the number of cell lines available for federal research dollars to those already in existence.
If none of the approved stem cell lines were developed without the aid of animal cells, it could "be a real killer" for stem cell research, researcher George Daley, of the Whitehead Institute for Biomedical Research, said, adding that he did not think any of the 60 lines are free of animal tissue. According to Kevin Ryder, a consultant to the American Cell Therapy Research Foundation, "This would be the exclamation point" on scientists' list of questions and reservations about the Bush policy. "We would have a very difficult time getting [stem cell therapies] advanced into the clinical setting unless we get the FDA to make some exceptions down the road," he added. Sen. John Kerry (D-Mass.) hinted that the rules governing stem cell research may need to be revised in light of the FDA disclosure. "The president's going to have to make available lines of stem cells that will be available for the full measure of research anticipated. If he doesn't, Congress will need to act to make that happen," he said (Gillis/Connolly, Washington Post, 8/24). The Senate Health, Education, Labor and Pensions Committee, chaired by Ted Kennedy (D-Mass.) is "likely" to take up the question when it meets next month to discuss stem cell research. Kennedy is expected to receive a "detailed" list of the 60 available lines next week, which should shed light on the viability of the available cells and whether any were created using alternative "feeder" cells (Carroll/Vandehei, Wall Street Journal, 8/24).This is part of the California Healthline Daily Edition, a summary of health policy coverage from major news organizations. Sign up for an email subscription.