Word: celles
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...does all this science affect the millions of patients banking on the promise of stem-cell therapies? Each of the investigators stress that their results, while exciting, have not yet been tested with human cells, although those studies are already under way. But the basic principles involved in generating stem cells in mice and man are the same, and with a few modifications, the scientists hope to have similar success with human cells. "It's likely to be the case that since this discovery is based on such fundamental cell biology principles, that the overarching rules [for mouse and human...
...indeed possible to take a skin cell from an adult patient and tweak it to revert to an embryonic-type cell, that would mean that any patient needing a stem-cell-based treatment could, in theory, heal himself. Last year, Yamanaka was the first to announce success with this approach, by exposing the cells to four growth factors and nutrients. But the stem cells he generated were genetically abnormal and unstable. Building on the initial technique, Yamanaka's group, as well as those led by Rudolph Jaenisch at Whitehead and Konrad Hochedlinger at HSCI, showed that the process does indeed...
...immediate obstacle to translating the results to human cells involves the way that the scientists turned back time on the mouse skin cells. They used a retrovirus vector, piggybacking the genes for the growth factors and proteins onto this infectious ferry. Retroviruses, however, like HIV, can cause infectious diseases and are not always easy to control, so before testing this approach in humans, researchers need to find other modes of transport for the critical compounds. The good news is that they need the genes to churn out their proteins for a only brief period of time, so using less virulent...
...other concern is perhaps more daunting-two of the four factors that can turn back the clock on adult cells so efficiently are known to cause cancer. One, in fact, was the first gene discovered to cause cancer in mice. "Figuring out how to reprogram cells without directly exposing the cell to the cancer-causing effects of these genes is a major area of scientific activity, and would have to occur before we could consider using similar factor in humans," says Eggan...
...meantime, Eggan's group has provided an alternative method for generating customized stem cells that would take advantage of the early-stage embryos frozen in IVF centers around the country. The most reliable way of generating patient-specific stem cells remains nuclear transfer-taking the nucleus from a patient's skin cell and inserting it into an egg that has had its nucleus removed. This hybrid then begins to divide, and within a few days, generates stem cells that are genetically identical to the patient. The problem, however, as Eggan puts it, is that "there are never any extra unfertilized...