Scientists have created the equivalent of embryonic stem cells from ordinary skin cells, a breakthrough that could someday produce new treatments for disease without the explosive moral questions of embryo cloning.
Research teams in the US and Japan showed that a simple lab technique can rival the complex and highly controversial idea of extracting stem cells from cloned embryos.
It was a landmark achievement on all fronts, defusing one of the most divisive debates in modern medicine and religion.
"This work represents a tremendous scientific milestone -- the biological equivalent of the Wright Brothers' first airplane," said Robert Lanza, whose company, Advanced Cell Technology, has been trying to extract stem cells from cloned human embryos.
"It's a win-win for everyone involved," said the Reverend Thomas Berg of the Westchester Institute, a Roman Catholic think tank.
At the White House, US President George W. Bush, who vetoed two bills to allow federal funding for stem-cell research, was described as "very pleased."
The new technique reprograms cells, giving them the chameleon-like qualities of embryonic stem cells, which can morph into all kinds of tissue, such as heart, nerve and brain.
The research was published online on Tuesday by two journals, Cell and Science.
The Cell paper is from a team led by Shinya Yamanaka of Kyoto University; the paper published by Science was by a team led by Junying Yu, in the lab of stem-cell pioneer James Thomson of the University of Wisconsin-Madison.
The scientists themselves were startled by their success.
"I was surprised when we achieved our results with the mouse," Yamanaka said.
Thomson said he was surprised it did not take longer to discover how to reprogram ordinary cells.
This is so simple, he said, that "thousands of labs in the US can do this, basically tomorrow."