Word: celles
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...get around political roadblocks, scientists are searching for another source of cells that is less ethically troublesome, ideally one that involves no embryo destruction at all. One approach is "altered nuclear transfer," in which a gene, known as CDX2, would be removed before the cell is fused with the egg. That would ensure that the embryo lives only long enough to produce stem cells and then dies. That strategy, promoted by Dr. William Hurlbut, a member of the President's Council on Bioethics, has its critics. Dr. Robert Lanza of biotech firm Advanced Cell Technology considers it unethical to deliberately...
Even if scientists discover an ideal source of healthy cell lines, there is still much to learn about how to coax them into turning into the desired kind of tissue. Parkinson's patients suffering from tremors caused by damaged nerves could benefit from replacement neurons, while diabetics who can't produce insulin could control their blood sugar with new pancreatic islet cells. But so far, no human ESCs have been differentiated reliably enough that they could be safely transplanted into people, although animal studies with human cells are under way. Not surprisingly, the groups closest to human trials...
When human trials finally begin, there's no method for precisely determining whether the transplanted stem cells are functioning correctly. "If we transplanted cells to regenerate a pancreas," says Owen Witte, director of UCLA's Institute for Stem Cell Biology and Medicine, "we can measure in your blood if you're producing insulin, but we can't see whether the cells have grown or evaluate whether they might grow into a tumor." So scientists are seeking to develop marking systems that let them trace a transplant's performance...
Less plastic than cord-blood cells are adult stem cells, which until recently researchers thought couldn't do much more than regenerate cell types that reflected the stem cells' origin--blood and immune cells from bone marrow, for example. Even so, some scientists believe adult stem cells may prove to be a powerful source of therapies. "In some cases, you may not want to go all the way back to embryonic stem cells," says Kurtzberg. "You may want something more specific or less likely to stray. You wouldn't want to put a cell in the brain and find...
ADULT STEM CELLS Why they are useful They exist in many major tissues, including the blood, skin and brain. They can be coaxed to produce more cells of a specific lineage and do not have to be extracted from embryos Drawbacks They can generate only a limited number of cell types, and they are difficult to grow in culture...