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List Where is the truth? Bob ---------------------------------------------- Studies cast doubt on efficacy of stem cells By ALEX DOMINGUEZ, Associated Press Wednesday March 13, 2002, 05:03:00 PM (AP) - Two new studies cast doubt on the tantalizing theory that adult stem cells can serve as the body's all-around repairmen, capable of converting into any type of cell to fight disease or replace faulty organs. The findings, if confirmed, could force scientists to focus more on embryonic stem cells, whose use is highly controversial because they are taken from embryos that are killed in the process. The studies could also influence the debate in Washington, where the Senate is expected to take up the issue in the next few weeks of whether to ban the use of cloning to create human embryos for medical research. Scientists have long known that stem cells from embryos are all-purpose cells that can transform themselves into different kinds of specialized tissue, such as muscle, bone, skin and organs. Researchers hope someday to harness this ability to treat various diseases and injuries. In recent years, scientists have found surprising evidence that stem cells taken from adult creatures have some of the same transforming properties, or plasticity. But the two new studies, conducted in separate laboratories in the United States and England and published online Wednesday by the journal Nature, cast doubt on that belief. In the two studies, embryonic stem cells from mice were marked with fluorescent tags and mixed in laboratory dishes with mouse bone marrow and brain cells. But instead of transforming into their neighboring cells, the stem cells simply merged their genetic material with the marrow and brain cells. The merged cells had twice the number of chromosomes as is normal. The researchers said the same phenomenon may have occurred in studies involving adult stem cells, and may have fooled scientists into thinking that the cells had transformed themselves. Petri dish experiments using bone marrow cells and adult stem cells have shown similar preliminary results, said University of Florida biologist Naohiro Terada, who led one of the research teams. Austin Smith of the University of Edinburgh wrote the second research paper. The new findings "call into question almost all of the data generated using adult stem cells," said Robert Lanza, medical director of Advanced Cell Technology, a Worcester, Mass., biotechnology company. ACT was not involved in the two studies but has a strong interest in embryonic stem cell research. Lanza said the findings could influence the political debate. "One of the main arguments that is being used to ban this research is the fact that adult stem cells have been found that can do the same thing - i.e., why kill human embryos if you don't have to?" Lanza said. "These two papers should send a message to lawmakers and to the public: It's premature to conclude that adult stem cells have the same potential as embryonic cells. In fact, it throws into question which if any of these adult stem cells can be harnessed to cure human diseases." However, opponents of embryonic stem cell research described the Nature papers as nonsense. "These studies don't show anything in particular as to how adult stem cells turn into different cell types in an adult body," Richard Doerflinger of the U.S. Conference of Catholic Bishops said in a statement. President Bush issued regulations last summer forbidding federal funding of human embryonic stem cell research except for experiments involving cell colonies that already exist. "I think the major point of both papers is to call into question all of this excitement that has been engendered by claims that there is plasticity in tissue stem cells," said Harinder Singh, a genetics and biology professor at the University of Chicago. Catherine Verfaillie, director of the University of Minnesota Stem Cell Institute, said the papers do not disprove adult stem cell plasticity findings by other researchers, including herself. However, she said it suggests stem-cell researchers should take a closer look at the chromosomes in the cells they are studying. Bob Martone [log in to unmask] http://www.samlink.com/~bmartone ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn