美國(guó)之音2007標(biāo)準(zhǔn)下半年AStem Cell Breakthrough Announced Amid Fierce D

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Stem Cell Breakthrough Announced Amid Fierce Debate

By Michael Bowman
Washington
07 June 2007

Scientists say stem cells offer the promise of cures to everything from cancer to spinal cord injuries. Stem cells are malleable and can be used to create virtually any kind of tissue. But there has been a fierce ethical debate over stem cell research, because until now, it was assumed the cells had to be harvested from human embryos, destroying them in the process.

But teams in the United States, using a process pioneered by a leading Japanese researcher, say they have now successfully transformed skin cells from mice into what are, in effect, embryonic stem cells.

Biologist Rudolf Jaenisch at the Massachusetts Institute of Technology led one of the teams.

"We can take any skin cell and treat it in a certain way," he said. "And after two or three weeks we will have embryonic stem cells which are indistinguishable from normal embryonic stem cells which have been derived from embryos."

Could the same be done with human skin cells? No one knows just yet, or whether embryonic stem cells created in such a fashion would be as useful in research as those harvested from living embryos. Scientists say further study will be required, and that definitive answers may not be forthcoming for some time.

In the meantime, the political and ethical debate over embryonic stem cells continues to rage in the United States. Jaenisch says he is well aware of the political furor surrounding embryonic stem cell research, and cautions against injecting his findings with regard to mice into the current debate.

"Many who are opposed to embryonic stem cell research will use this [breakthrough] and say, 'Ha! We do not need it [to use embryos].' This is the wrong conclusion," he said.

Meanwhile, in the U.S. Congress there has been more contentious debate on legislation to allow more federal funding for embryonic stem cell research, legislation that President Bush has said he will veto.

Before Thursday's vote to send the measure to the president's desk, Indiana Republican Mike Pence stood in opposition.

"Congress is once again poised to pass legislation that authorizes the use of federal tax dollars to fund the destruction of human embryos for scientific research," he said. "I believe that life begins at conception. It is morally wrong to create human life to destroy it.

California Democrat Lynn Woolsey has a different point of view, stressing the seemingly limitless potential of stem cells to improve human health.

"How can we tell a parent watching a child suffering from cancer that we are not going to do every single thing possible to save that child? How can we tell a teenager that there is a chance we could repair a damaged spinal chord, but we are not going to pursue it," she asked.

President Bush has authorized federal funds for stem cell research involving a small number of stem cell lines from discarded embryos. U.S. researchers say those lines are badly contaminated and of little scientific value, and that the United States is falling behind other nations with few restrictions on such research.