Scientists make equivalent of stem cells in mice
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By Sam Ogden via The Whitehead Institute, via AP
In a significant step toward a long-sought goal, scientists say they've converted mouse skin cells into the apparent equivalent of embryonic stem cells. That may lead to a way around the controversy about using the embryonic cells to treat disease.
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By
Dan Vergano, USA TODAY
[/align]In a big step toward a long-sought goal, three teams of scientists say they've produced the equivalent of embryonic stem cells, at least in mice, without taking the controversial step of destroying embryos.
[/align]Genetic "reprogramming" of mouse cells can create cells that mimic embryonic stem cells, biologists report Wednesday, pioneering a new approach to so-called "regenerative" medicine.
The findings by three teams publishing in the journals
Nature and
Cell Stem Cell mean the reprogrammed cells may offer a less-controversial way to make rejection-free tissues for transplant patients. Embryonic stem cells are master cells capable of becoming any cell in the body, and thus hold the promise of generating tissue that can treat such diseases as diabetes or cancer.
But research would have to show that the same process could work in human cells too, the study authors say.
"A human is not a mouse," cautions Marius Wernig of the Whitehead Institute for Biomedical Research in Cambridge, Mass, who led one of the two
Nature studies. He says scientists have no evidence yet that the process, however promising, will work for human cells.
FIND MORE STORIES IN:Konrad Hochedlinger
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'NATURE' REPORT: Simple switch turns cells embryonic
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"We have reprogrammed mature adult cells into ones virtually identical to an embryonic stem cells," added Wernig. "I would not have believed this was possible."
The teams genetically altered connective tissue cells called fibroblasts to give them the flexibility to turn into all other kinds of tissue, the distinguishing characteristic of embryonic stem cells.
The teams used viruses to deliver four genes into fibroblasts, and allowed the reprogrammed cells to divide for at least seven days. The selected cells demonstrate all the capabilities of embryonic stem cells, says
Cell Stem Cell report senior author Konrad Hochedlinger of the Harvard Stem Cell Institute. The teams injected the cells into early mouse embryos, which were then implanted into the wombs of female mice, producing mouse pups, "the real test of whether the cells act like embryonic stem cells," says Hochedlinger.
While embryonic stem cells are seen as holding great biomedical promise, creating the cells requires the destruction of embryos, a source of ongoing controversy in the field.
"Because adult cell reprogramming does not raise the moral problem of creating or destroying embryos, it may offer a way for people of all faiths and all ethical backgrounds to study, use, subsidize, and enjoy any therapeutic benefits of 'pluripotent' stem cell research," says Richard Doerflinger of the United States Conference of Catholic Bishops, a prominent critic of embryonic cell research, by e-mail.
"The studies are exciting and important," says stem cell biologist George Daley of Children's Hospital Boston. But he cautions the reprogrammed cells carry multiple viruses, while embryonic stem cells are free of genetic modifications.
In a related paper, Harvard researchers led by Kevin Eggan report they have created mouse embryonic stem cells from defective embryos in mice. Such embryos occur in 3-5% of human in-vitro fertilization attempts and are now routinely discarded as non-viable by fertility clinics. The researchers suggest these non-viable embryos may also serve as a source of research cells.
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document.write(niceDate('6/6/2007 1:22 PM'));
22h 16m ago
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document.write(niceDate('6/6/2007 1:23 PM'));
22h 15m ago
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Brent Jones
More promising possibilities; stem cell research
