President Barack Obama has lifted a ban on public funding for stem cell research involving the destruction of human embryos.
The move comes as scientists are increasingly abandoning embryonic stem cell research in favour of more promising alternatives.
Along with the UK, America has set itself apart from the 21 nations who have banned such experimentation.
The restrictions Mr Obama has overturned were introduced in 2001 to block federal funding for research using new lines of stem cells derived from embryos. The ban did not cover lines which had already been developed.
Commentators speculate that the move may encourage Congress to go further by lifting a restriction preventing federal money being used to create human embryos purely for use in research.
The policy shift towards embryonic research comes despite significant advances in recent months involving alternative stem cell sources, leading campaigners to dub embryonic stem cell research “yesterday’s bad idea, not tomorrow’s future”.
Last week a team of scientists from Britain and Canada announced that they had overcome safety concerns surrounding a new way of reprogramming a patient’s cells to behave like ones derived from embryos.
Professor Sir Ian Wilmut, who led the team that created Dolly the Sheep, has championed the technique, writing: “These cells have the benefits of both embryo-derived stem cells and cells from the tissues of the patient.”
In November last year, scientists heralded a “new age in surgical care” as a woman was successfully given a new windpipe grown from her own stem cells. The breakthrough did not involve the destruction of human embryos.
Mr Obama made his stance on embryonic stem cell research very clear while campaigning for office. “I strongly support expanding research on stem cells,” he said.
“I believe that the restrictions that President Bush has placed on funding of human embryonic stem cell research have handcuffed our scientists and hindered our ability to compete with other nations”.
He signed yesterday’s order pledging to “vigorously support” such research.
Tony Perkins, president of the Family Research Council, called Mr. Obama’s “deadly executive order” a “slap in the face to Americans who believe in the dignity of all human life”.
Anthony Ozimic, political secretary at the British campaign group Society for the Protection of Unborn Children, commented: “President Obama’s decision comes at a time when researchers have started to conclude that embryonic stem cell research is scientifically flawed and that alternative forms of stem cell research which don’t involve embryos are far more successful.
“Yet he is ready to provide funds for scientists who will create and destroy human embryos with no regard to their human status, their rights and their dignity as fellow members of the human family. By so doing, he reveals himself as a willing tool of a powerful lobby of vested interests among research companies and eugenicist academics.
“He promised a new approach to policy but embryonic stem cell research is yesterday’s bad idea, not tomorrow’s future.”