Cloning breakthrough reignites political debate.

The recent announcement that scientists have derived a stem cell line from a cloned human embryo has the long-term potential to offer tailored disease treatments, but in the short term could lead to restrictions on this research.

The findings, reported by a group of South Korean researchers (Science [Epub ahead of print], Feb. 12, 2004, www.sciencemag.org/cgi/content/abstract/1094515), are fueling the ongoing debate on whether Congress should act to ban cloning and whether that ban should prohibit cloning for both reproduction and research purposes.

The South Korean researchers reported that somatic-cell nuclear transfer (SCNT) was used to develop embryonic stem cells. The cells were harvested from a human blastocyst that was produced by transferring the nucleus of a cell into a nucleus-free egg from the same donor.

The finding is a first step toward using SCNT, sometimes called "therapeutic cloning," to grow cells that could carry the genetic material of a patient and therefore treat degenerative disorders like diabetes, osteoarthritis, and Parkinson's disease without immune rejection, they noted.

But the researchers said that to successfully derive immunocompatible human embryonic stem cells from a living donor, scientists will need to develop a more reliable and efficient method for producing cloned embryos and embryonic stem cell isolation.

In addition, further improvement in SCNT protocols and in vitro culture systems are needed before the technique can be used for cell therapy, the researchers said.

"It's an extremely high quality and important piece of science," said Sean Tipton, spokesman for the American Society for Reproductive Medicine.

Mr. Tipton said he hopes the discovery will change the political debate. Now that it's known that SCNT can create viable human stem cell lines, the use of the technology needs to be protected, he said.

"At the very least, it makes it safer that the Senate will not pass a bad cloning bill," he said.

Dr. Lee P. Shulman, head of reproductive genetics at Northwestern University and a board member with the Association of Reproductive Health Professionals, said that although cloning is unlikely to lead to new therapeutic options in the near future, the research should be continued without restraints from Congress or the Bush administration.

"Exploration and discovery have risks," Dr. Shulman said. "It's very foolhardy to say because of those risks we're not going to continue the research." The best precaution is an "ethical, well-monitored, peer-reviewed process."

But the research does have plenty of opponents.

The Christian Medical Association condemned the action. "I'm disappointed that we're straying this far without some ethical constraints being applied," Dr. Gene Rudd, an ob.gyn. and the group's associate director, told this newspaper.

Dr. Rudd said the group's position is that all embryos, whether they are created through cloning or other means, should be protected.

The ethical concerns that are raised by research involving human cloning are too significant to allow the work to continue, he said. Instead, researchers should focus on the study of adult stem cells and cord blood stem cells.

There are currently no federal laws in the United States that regulate cloning. The U.S. House passed a bill in 2003 (H.R. 534) that would have banned all forms of cloning, both therapeutic and reproductive. However, legislation to ban cloning has not gained traction in the Senate.

The American Medical Association has a policy that "cloning for biomedical research is consistent with medical ethics."

But the AMA also notes that physicians are free to decide whether to participate in this type of research or to use the products that result from this research.

BY MARY ELLEN SCHNEIDER

Senior Writer