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Cloning won't help patients anytime soon By Rosie Mestel Los Angeles Times In Seattle, pioneers in cloning urge bans on reproductive use The report of a successfully cloned human embryo was a milestone in the field of stem-cell research, but the medical rewards of such endeavors are still years in the future, scientists said yesterday. Cloning human embryos to a stage in which stem cells can be extracted would theoretically permit scientists to create genetically matched tissues that can be inserted into patients' bodies to treat a range of diseases, such as diabetes, Parkinson's and multiple sclerosis. Because the tissues would be perfect genetic matches to the patient, they would be unlikely to be rejected by the body. But before stem-cell therapy can be used in medicine, many hurdles must be overcome. The achievement of South Korean scientists in cloning a human embryo and extracting stem cells is only one of many necessary breakthroughs. It will likely take years, maybe decades, before the treatments become a reality. Scientists must learn how to create specific body cells with sufficient purity, longevity and stability. "It's like herding cats, trying to get these cells to all do the same thing," said David Anderson, professor of biology at the California Institute of Technology. "They start whispering among each other and all go off in different directions to form different tissues." Researchers must also show that such tissues can be safely inserted into a test animal and perform the functions of the cells they are meant to be. Finally, researchers must show that the therapy works in people. A patient with diabetes, for example, could be helped with stem cells that have been coaxed into becoming insulin-secreting pancreas cells, boosting the body's insulin-producing ability. So far, the overwhelming majority of such work has been conducted not with human embryonic cells but with animal cells. The work is based on decades of research into basic embryo development, with some impressive results. In one instance, researchers at Columbia University used a complex series of chemical treatments to turn an embryonic stem cell into a type of nerve cell called a motor neuron. First they turned it into a kind of generic nerve cell, capable of becoming many kinds of nerves. Then they gave it additional chemical treatments to prod it into becoming a motor neuron. The scientists grafted the cells into chicken embryos. The cells appeared to link up with other nerves just as if they were motor neurons. In another experiment, a group at the National Institutes of Health created cells that secrete the brain chemical dopamine, which is deficient in patients with Parkinson's. When the cells were grafted into the brains of mice with a Parkinson's-like condition, certain behaviors (such as the ability to grasp food with both paws) improved, said Ron McKay, the NIH stem-cell researcher whose lab conducted the experiment. "I want to avoid saying the mice were cured; we've got a long way to go," McKay said. "But it does look promising." Other areas of stem-cell research are not as far along. For instance, some scientists have reported the creation of insulin-secreting cells, but other scientists believe the cells were sucking up insulin from the culture medium they were grown in and spitting it out. Copyright © 2004 The Seattle Times Company __________________________________ Do you Yahoo!? Yahoo! Finance: Get your refund fast by filing online. http://taxes.yahoo.com/filing.html ________________End of message______________________ Archives and tools for the Disability-Research Discussion List are now located at: www.jiscmail.ac.uk/lists/disability-research.html You can JOIN or LEAVE the list from this web page.