Scientists have invented an efficient way to produce apparently safe alternatives to human embryonic stem cells without destroying embryos, a long-sought step toward bypassing the moral morass surrounding one of the most promising fields in medicine.

A team of researchers at the Harvard Stem Cell Institute in Boston published a series of experiments Thursday showing that synthetic biological signals can quickly reprogram ordinary skin cells into entities that appear virtually identical to embryonic stem cells. Moreover, the same strategy can then turn those cells into ones that could be used for transplants.

"This is going to be very exciting to the research community," said Derrick J. Rossi of the Children's Hospital Boston, who led the research published in the journal Cell Stem Cell. "We now have an experimental paradigm for generating patient-specific cells highly efficiently and safely and also taking those cells to clinically useful cell types."

Scientists hope stem cells will lead to cures for diabetes, Alzheimer's disease, spinal cord injuries, heart attacks and many other ailments because they can turn into almost any tissue in the body, potentially providing an invaluable source of cells to replace those damaged by disease or injury. But the cells can be obtained only by destroying days-old embryos.

The cells produced by the Harvard team, known as induced pluripotent stem cells, or iPS cells, would avoid that ethical objection and could in some ways be superior to embryonic stem cells. For example, iPS cells could enable scientists to take an easily obtainable skin cell from any patient and use it to create perfectly matched cells, tissue and potentially even entire organs for transplants that would be immune to rejection.

'Game changer'



While cautioning that the work needs to be repeated elsewhere and explored further, other researchers said the technique appears to represent a major development in the promising field of "regenerative medicine," which aims to create treatments tailored to individual patients.

"All I can say is 'wow' - this is a game changer," said Robert Lanza, a stem cell researcher at Advanced Cell Technology in Worcester, Mass. "It would solve some of the most important problems in the field."

The results were so striking that the Harvard Stem Cell Institute where Rossi works had already ordered every scientist working on iPS cells to switch to the new process.

"This paper is a major paper, in my view, in the field of regenerative medicine," said Douglas A. Melton, a leading stem cell researcher who co-directs the institute.

The announcement comes as the future of federal funding for embryonic stem cell research hangs in doubt. A federal judge stunned the field Aug. 23 by ruling that the Obama administration's more permissive policy for funding the research violated a federal law barring taxpayer money from being used for studies that involve destroying human embryos. An appeals court Tuesday let the funding continue until the case is resolved.

Opponents of human embryonic stem cell research seized on the development as the most convincing evidence yet that the morally questionable cells are unnecessary.

"With each new study it becomes more and more implausible to claim that scientists must rely on destruction of human embryos to achieve rapid progress in regenerative medicine," said Richard M. Doerflinger of the U.S. Conference of Catholic Bishops.