News that Chinese researchers have succeeded in growing healthy living mice from mouse skin cells takes scientists a significant step closer to human cloning, experts say, and thus figures to reopen debate about the ethics of such reproductive techniques. The new feat — in which animals were grown from cells that had been reverted to their embryonic state — is technically different from cloning. But the outcome is the same in both cases: a genetically identical copy of the donor animal.

“We are fast forwarding to the era of designer babies,” said Dr. Robert Lanza, chief scientific officer at Advanced Cell Technology Inc. in Worcester, Mass., who was not involved in the studies. “We have gone from science fiction to reality.” Cloning, in which the nucleus is removed from a cell and implanted in a fertilized egg, has never been achieved in humans. Nor has the new technique — using what is known as induced pluripotent stem, or iPS, cells — been tested in them. Because that process works in mice, however, it should work in humans, Lanza added.

“We now have the technology to create iPS cells from skin or hair follicles,” he said in reaction to Thursday’s announcement.

“There are a dozen approaches that could be used. What’s very troubling is that if you have a piece of skin from anybody — Albert Einstein, Marilyn Monroe, Michael Jackson — you could create a child.”

Said biologist Kathrin Plath of the University of California, Los Angeles’ Broad Center of Regenerative Medicine and Stem Cell Research, who was not involved in the research: “That is an experiment that shouldn’t be done. If you look back at the mouse cloning experiments,” she noted, many died shortly after birth or suffered from genetic abnormalities.

The researchers involved in the new research agreed.

“It would not be ethical to attempt to use iPS cells in human reproduction,” Fanyi Zeng of the Shanghai Jiao Tong University said in a telephone news conference. “It is important for science to have ethical boundaries.”

Her study, she added, was “in no way meant as a first step in that direction.”

But even as the finding revives the cloning issue, it should relieve much of the debate about the morality of using embryonic cells in research on curing diseases like diabetes and Parkinson’s disease because it provides a source of tissue that can be obtained without destroying fetuses.

Researchers first produced iPS cells two years ago, but there have been lingering doubts about whether the cells are truly identical to embryonic cells or instead are capable of producing only some types of body cells.

The new results, published online Thursday by the journals Nature and Cell Stem Cell, appear to erase those doubts. The results also open the door to applications beyond producing stem cells for medicinal purposes, including the production of endangered species and the reproduction of prized farm and other animals.