British Scientists Say Embryos Essential for Disease Research

      LONDON (AP) - Despite recent advances toward using adult cells to fight disease, embryos provide the only realistic hope for cell-based treatments in the near future, Britain''s premier scientific organization said Tuesday.

      Up to 10 percent of the population could benefit from such therapy, but without research on embryos, development could be delayed an extra 20 years, said Richard Gardner, a professor of zoology at Oxford University and lead author of the report.

      The advice from the Royal Society, an institution of Britain''s most distinguished scientists, comes weeks before Parliament is to debate whether to permit experiments on cells extracted from embryos and the creation of embryos by cloning.

      If the change is approved, Britain would the the first country to specifically authorize cloning.

      The debate centers on the potential of cells known as stem cells, the master cells of the body which are unprogrammed and can become nearly every cell type in the body, from blood and bone to heart muscle and eyeballs.

      When an egg is fertilized the result in the first 14 days consists mainly of stem cells, experts say. When stem cells divide, they can give rise either to another stem cell or to one of the 200-odd specialized cell types that make up the human body.

      They don''t start to become specialized cells until after 14 days, Gardner said.

      The idea is to extract the stem cells from an embryo when it is three or four days old, and let them keep dividing in a petri dish in a lab. Scientists hope they will be able to direct the stem cells to create the specific types of cells needed, whether those be nerve cells to repair brain damage in Parkinson''s disease, liver tissue to regenerate a diseased liver, or insulin-producing pancreatic cells to give to diabetics.

      Stem cells are also present in adults and recent findings show that a blood stem cell can give rise to a nerve stem cell, indicating that adult master cells are more versatile than previously thought.

      Opponents of embryo research and of cloning argue that advances in adult stem cell research have rendered embryos and cloning unnecessary.

      ``But they have a restricted fate,'' said Dr. Robin Lovell-Badge, head of developmental genetics at the National Institute for Medical Research in London. ``The changes are much more restricted. We believe it is going to take longer to get this to be of benefit.''

      The later in life the adult cells are harvested, the lower their capacity to keep growing and the only time they have been shown to produce a wide variety of cell types is when they have been placed inside an early-stage mouse embryo, Gardner added. Embryonic stem cells can keep growing indefinitely without damage, he added.

      The scientists argued that embryo research should not be banned while experts try to make progress with adult cells and that following the two routes will give quicker results.

      The technique will give doctors an opportunity to use transplants for many more diseases than they do now, experts say.

      Gardner envisions stocks of stem cells stored for transplants, like blood banks. He said humans would be divided into groups according to their stem cell type, as they are for blood groups.

      And scientists expect that using cells extracted from embryos created by cloning a cell from the sick person would overcome the problem of transplant rejection.

     

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