WASHINGTON — For the first time, scientists have turned ordinary skin cells into what appear to be embryonic stem cells — without having to use human eggs or make new human embryos in the process, as has previously been required, a Harvard research team announced yesterday.

The technique uses laboratory-grown human embryonic stem cells — such as the ones President Bush has approved for use by federally funded researchers — to "reprogram" the genes in a person's skin cell, turning that skin cell into the equivalent of an embryonic stem cell itself.

The new approach, which is to be published this week in the journal Science but was made public yesterday on the journal's Web site, is still in an early stage of development. But if further studies confirm its usefulness, it could offer an end run around the heated social and religious debate that has overshadowed the field of human embryonic stem-cell research.

Because the new stem cells made this way are essentially rejuvenated versions of a person's own skin cells, the DNA in the new stem cells matches the DNA of the person who provided the skin cells. In theory at least, that means that any tissues grown from those newly minted stem cells could be transplanted into the person to treat a disease without much risk that they would be rejected, because they would constitute an exact genetic match.

Until now, the only way to turn a person's ordinary cell into a "personalized" stem cell was to turn that ordinary cell into an embryo first, then destroy the embryo to retrieve the new stem cells growing inside — a process widely known as "therapeutic cloning."

That prospect, like others in the promising arena of human embryonic stem-cell research, has stirred strong emotions among those who believe that days-old human embryos should not be intentionally destroyed.

Embryonic stem cells are capable of becoming virtually any kind of cell or tissue and are being intensely studied around the world as the core of a newly emerging field of regenerative medicine, in which researchers hope to grow new tissues to revitalize ailing organs.

Although human embryonic stem cells have never been tested in humans, some researchers expect human clinical trials to begin within a year or so.

Researchers caution, however, that like many other nascent therapies that initially seemed promising, stem cells might never live up to their promise.

If some lingering, and potentially daunting, uncertainties can be dealt with successfully, the new technique "may circumvent some of the logistical and societal concerns" that have hampered much U.S. research, reported Chad Cowan, Kevin Eggan and colleagues from the Harvard Stem Cell Institute in the Science article.

More immediately, the new work is likely to have an impact on Capitol Hill, where the Senate is poised to vote on legislation — already passed by the House — that would loosen Bush's restrictions on human embryonic research.

Earlier this month, Senate Majority Leader Bill Frist, R-Tenn., surprised many of his colleagues by announcing that he would break with the president and support the Senate bill, which Bush has promised to veto.

Some opponents of relaxing the current restrictions have argued that new techniques soon will eliminate the need to use human eggs or embryos to make cells that are, for all intents and purposes, human embryonic stem cells. For some months, they and others have predicted that if such new findings were to emerge, they could shift the balance of votes in the Senate.

The researchers emphasized in their report that the technique is still far from finding application in medicine. Most important, they noted: Because it involves the fusion of a stem cell and a person's ordinary skin cell, the process leads to the creation of a hybrid cell.

While that cell has all the characteristics of a new embryonic stem cell, it contains the DNA of the person who donated the skin cell and also the DNA that was in the initial embryonic stem cell.

At some point before these hybrid cells are coaxed to grow into replacement parts to be transplanted into a person, that extra DNA must be extracted, the researchers said.

The team described this task as a "substantial technical barrier" to the clinical use of stem cells made by the new technique.

They did not mention that several teams, including one in Illinois and another in Australia, have recently said they are making progress removing stem-cell DNA from such hybrid cells.

None of those teams has published details of their results. But several leading researchers have said they believe it would be feasible to remove the extra DNA.

"Their data are certainly very good ... and quite significant," said John Gearhart, a stem-cell researcher at Johns Hopkins Medical Institutions. But the extra DNA "is problematic."

"I think we have to keep our eye on the ball here," Gearhart said. "If this stuff proves to work, that's wonderful. But we're just not there yet, and it's going to take a long time to demonstrate that. Meanwhile, other techniques already work well. So let's get on with it."

Still, it is fascinating, Gearhart said, to see such good evidence that something in embryonic stem cells is able to turn an ordinary skin cell into the equivalent of an embryonic stem cell — a genetic alchemy apparently accomplished by turning key genes in the skin cell either "on" or "off."

Even if the work does not lead directly to clinical applications, he and the Harvard researchers said, it is likely to boost the amount and quality of research into what stem cells really are and how they work.