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Thread: Early Success Seen With 2nd Type of Stem Cell

  1. #1

    Early Success Seen With 2nd Type of Stem Cell

    July 26, 2001

    Early Success Seen With 2nd Type of Stem Cell

    A second kind of human embryonic stem cell appears to have demonstrated promise in repairing damaged tissues by helping paralyzed mice regain some powers of movement.

    Dr. John D. Gearhart, a biologist at Johns Hopkins University, said the mice, whose spinal nerve cells had been destroyed by a virus, managed to move again, though not perfectly, after receiving injections of human embryonic cells.

    The result, which Dr. Gearhart described at a scientific meeting at the Jackson Laboratory in Bar Harbor, Me., seems likely to influence the stem cell debate because of the striking nature of paralyzed animals regaining the power to walk.

    Other scientists cautioned that the clinical relevance of the finding was far from clear. But the cells have an interesting political advantage: Dr. Gearhart derived them from fetuses that were aborted for the sake of the mother's health, not from the discarded embryos produced in fertility clinics. In his view, work with the cells would not be prohibited by the Congressional stipulation that no federal money be used for research in which a human embryo is destroyed.

    Dr. Gearhart and Dr. James Thomson of the University of Wisconsin reported in November 1998 that they had isolated human embryonic cells. Dr. Thomson's cells, known as embryonic stem cells, have received most of the attention; more scientific work has been done with them, and opponents have focused their fire on the cells because they require the destruction of human embryos. Dr. Gearhart's cells are called embryonic germline cells because they form the egg or sperm of the next generation.

    Though the germline cells do not involve destroying embryos, they were placed in the same category as the embryonic stem cells by the National Institutes of Health in drawing up its research guidelines.

    Both types of cell presumably have the potential to form all the cell types required by the human body. But biologists are not convinced that the two are equally versatile, and they prefer to work with the Thomson-type cells because more is known about them.

    Dr. Gearhart, however, has shown in test tube experiments that his germline cells have many of the same properties as embryonic stem cells.

    The use of his cells in making mice walk is a further demonstration of their versatility. The mice experiments were first reported in The Wall Street Journal yesterday.

    The mouse work is "not something that anyone should hang their hat on," said Dr. Irving Weissman, a stem cell expert at Stanford University, noting that the exact role played by the human embryonic cells in helping the mice remained unclear.

    Dr. Ronald McKay, a stem cell researcher at the National Institutes of Health, expressed concern that the videotape of walking mice would make people expect quick results.

    "In my view," Dr. McKay said, "we really are all in for a decade's worth of careful work here - it won't happen by magic."

    The publicity given to the success of the embryonic germline cells could encourage opponents to propose them as an alternative to embryonic stem cells. But Dr. Weissman said he believed such opponents would be hostile to research with either cell.

    Valerie Estess, a founder of Project ALS, which paid for the mouse work by Dr. Gearhart, Dr. Douglas A. Kerr and other colleagues, said her organization supported research with both kinds of cell and was not trying to boost the germline variety. The mice treated with the cells were damaged in such a way as to mimic ALS, also known as Lou Gehrig's disease.

    "We never intended for the videotape to be released prior to publication," Ms. Estess said. "But various of the researchers felt that given the political climate it was important for the people in power to have visual proof that embryonic cells have promise."

    The Clinton administration decided that government-financed researchers could work with the embryonic cells as long as others destroyed the embryos from which the cells are derived, a decision still under review by the Bush administration. Dr. Gearhart, who was not available today, has said that his cells have always been eligible for federal financing and would continue to be even if the administration overturns the Clinton ruling.

  2. #2
    This work by John Gearhart is important. It expands the repertoire of stem cells that may be useful therapeutically. Embryonic stem cells are by definition obtained from embryos which are less than 6 weeks of age. Fetal stem cells are those that are obtained from fetuses which are more than 6 weeks and before birth. Neonatal stem cells are those obtained from newborns. There is at present still no name for cells that are obtained from young animals. And of course adult stem cells are obtained from people or animals after puberty. Wise.

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