There's very big news today in the stem cell world.

Scottish researcher Ian Wilmut told the UK Telegraph yesterday that he "decided a few weeks ago not to pursue nuclear transfer." In other words, the man who came to fame by producing the world's first cloned mammal - and who is sitting on one of two licenses to clone human embryos that the British government has issued - is giving up on cloning techniques in stem cell research.

Wilmut says he now believes that pluripotent stem cells can be more efficiently produced by a technique involving the direct reprogramming of ordinary body cells, which Japanese researchers led by Shinya Yamanaka at Kyoto University accomplished in mice earlier this year. The creation of these reprogrammed cells, called induced pluripotent stem (iPS) cells, requires no eggs or embryos.

Wilmut's surprise move could shift both the scientific and the political debates about stem cell research. If direct reprogramming continues to show success - and Wilmut says he has "no doubt that in the long term" it will - the argument for research cloning will be seriously weakened, and it will be even less justifiable to ask women to undergo risky and invasive egg retrieval procedures to provide research materials. What's more, we may soon see the end of embryonic stem cell research as a wedge issue in U.S. politics.

The Telegraph's science writer said that Wilmut's announcement "will send shockwaves through the scientific establishment." An editorial in the paper predicted that it "could mark the end of the road for the [cloning] technique, on which vast sums of money have been spent to little effect."

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