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Wednesday, June 6, 2007

Harvard, Whitehead scientists report embryonic stem cell advances

By Colin Nickerson, Globe Staff

Scientists in Massachusetts and Japan say they have created embryonic stem cells using procedures that might overcome some of the ethical objections to the controversial research as well as a major scientific hurdle.

Most dramatically, three of the four research findings announced today used a highly experimental approach that avoids the destruction of embryos, which critics equate to taking a life. Instead, they used genes and retroviruses to coax adult cells back to an embryo-like state.

The other project, meanwhile, points to a new, readily available source of embryonic stem cells, which would allow researchers to bypass a bottleneck in current efforts at Harvard University to clone human stem cells genetically matched to a patient with a particular disease -- the inability to find women willing to donate unfertilized eggs for the research.

All of the research reported in today's Nature and Cell Stem Cell involved mice, but scientists say they believe the results could be replicated in humans.

"These new studies, done with mice cells, point the way to experiments that can be tried with human cells," said Douglas Melton, a Harvard stem cell scientist. "This represents some of the most exciting work in stem cell biology and genetic reprogramming."

In one of the papers, Melton's colleague at the Harvard Stem Cell Institute, Kevin Eggan, defied long-standing scientific dogma that fertilized eggs cannot be used to clone embryonic stem cell lines. Eggan carried out somatic cell nuclear transfer -- cloning -- by removing chromosomes from a one-cell fertilized egg and replacing it with DNA from another, mature cell. The modified cell began dividing, and he then harvested stem cells from the resultant embryo.

Although less razzle-dazzle than the techniques used in the other research, Eggan's work holds the best prospect of creating human embryonic stem cell lines in the near future.

The study by Eggan suggested that researchers could use the genetically-defective fertilized eggs discarded by the thousands daily at fertility clinics across the United States. Such one-cell embryos are treated as waste because they stand no chance of attaching to the womb and forming a healthy embryo.

"This represents a wonderful way of obtaining something good -- medical research that could lead to therapies for human disease -- out of something that would just be thrown away," Eggan said in an interview.

The findings by scientists from Harvard, the MIT-affiliated Whitehead Institute, Massachusetts General Hospital, and Japan's Kyoto University also represented the most successful attempts to date to find new ways to make embryonic stem cells that might overcome some of the ethical opposition from religious groups who oppose destruction of human embryos and from womens groups worried about the implications of female donors undergoing tricky hormonal therapy to produce eggs for research.

"All in all, this is encouraging, exciting progress that shows real willingness among scientists to weigh ethical concerns even as they pursue science objectives," said Dr. William Hurlbut, a neuroscientist and ethicist at Stanford University who serves on the President's Council on Bioethics. "The science is critical, of course. But so are many ethical concerns. We've got to calm down as a nation and stop the acrimony and misrepresentation flung by both sides."

Embryonic stem cells, considered crucial to medical science and eventual treatment for an array of terrible diseases, have the ability to form any of the 220 basic tissue types in the body -- from bone cells to brain cells.

But research on the cells has been slowed in the United States since President Bush, citing concerns about destruction of embryos, sharply limited federal funding of the science in 2001.

Work done by teams working independently of one another at Harvard, the Whitehead Institute, and Kyoto University involved the genetic manipulation of mouse skin cells back into an embryonic state. No eggs were used, no embryos destroyed -- a stunning advance, although perhaps difficult to replicate in humans.

"You can really turn back the clock from adult to embryonic stem cells," said Konrad Hochedlinger of the Harvard Stem Cell Institute and Massachusetts General Hospital's Center for Regenerative Medicine. "But success in humans might be much more difficult than in mice."

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