Stem cell researchers in the US have reacted to comments made last week's by Elias Zerhouni, director of the US National Institutes of Health. They question his assertion that the available stem cell lines are sufficient to meet research needs. Zerhouni stated that the restrictions placed on federally-funded embryonic stem cell (ES cell) research by President Bush were not harming research.
In August 2001, President Bush announced a national policy limiting federally-funded stem cell research to ES cell lines created on or before that date. Bush's policy allows federal funding for experiments involving stem cells already derived from embryos but not for research that would involve the creation and destruction of embryos. Since August 2001, scientists have developed techniques enabling them to grow ES cells without using mouse cells. Scientists believe that these types of ES cell are both medically promising and suitable for use in clinical trials, but the Bush policy will not allow federal funds to be used in such research.
Last month a panel of experts said that it would be unethical and risky to use the 78 ES cell lines currently eligible for use by federally-funded researchers for transplantation into human patients. The panel, made up of scientists, philosophers, ethicists and lawyers, said that because the federally-approved ES cell lines were grown using feeder cells from mouse embryos, humans could become infected with mouse viruses. Zerhouni refuted this argument, saying that it was not yet proved that ES cells will be medically useful and that the Food and Drug Administration has adequate guidelines for human safety in clinical trials.
John Gearhart, one of the scientists originally responsible for deriving human ES cells, currently a professor at the Johns Hopkins Medical School, said that stem cell researchers think that both Zerhouni's arguments 'are weak'. 'It is clear no-one will use those lines in humans', he said. Other scientists warned that the restrictions were continuing to be a 'brain and resource drain'.