Nov. 13 (Bloomberg) -- A U.S. scientist ended his collaboration with Hwang Woo Suk, the South Korean researcher credited with making the first embryonic stem cells genetically matched to living adults, saying that human eggs used to make the cells were unethically obtained.

Gerald Schatten, a University of Pittsburgh stem cell scientist, will scrap the 20-month collaboration after learning that charges that Hwang paid a lab worker to donate egg cells might be true, the university's school of medicine said in an e- mailed statement. Hwang couldn't be reached for comment.

Schatten's departure might spell the end of any U.S. involvement in Hwang's Stem Cell Research hub, established in Seoul last month to speed research into growing tissues and organs for transplant into patients, said Arthur Caplan, a University of Pennsylvania School of Medicine ethicist. With so much attention focused on the ethics of stem cell research, the appearance of a single breach may be enough to drive any collaborators away, he said.

``The international community will be backing away fast'' Caplan said in a telephone interview. ``Cloning research is too controversial for people to get two or three strikes for an out.''

American scientists have hailed Hwang's ability to carry out work that is restricted in the U.S. To discourage destroying embryos President George W. Bush, banned U.S. funding for research on embryonic stem cell strains created after August 2001. States, private organizations and universities can pay for laboratory research as long as they don't use U.S. funds.

Therapeutic Cloning

Hwang reported in May that he had developed a technique for making large batches of embryonic stem cells that could be matched to patients by using DNA taken from an individual's skin cell. Hwang put genes from the skin cell into a donor egg cell to create embryos from which stem cells can be extracted, a process known as therapeutic cloning.

Scientists and drug developers around the world hailed Hwang's work as a critical step toward an era of medicine in which fresh new tissues, genetically matched to patients, would be grown to replace dying cells in the brain, heart, and other organs. Researchers hope the cells can jump-start treatment for Alzheimer's disease, diabetes and spinal cord injuries.

On Oct. 19 Schatten and scientists in the U.S., U.K. and other nations joined Hwang in Seoul to announce with much fanfare the formation of a stem cell bank to supply labs around the world with the cloned embryonic stem cells.

The bank, with Schatten named to head its board of directors, was planning to create sites in San Francisco and London where technicians trained by Hwang would create embryonic stem cells from patients with various diseases as a way for scientists to study the basic biology of the disorders, the Pittsburgh researcher said in an interview Oct. 24.

Postage Stamp

University of Pittsburgh said Schatten wasn't going to comment at present beyond the statement the school released late yesterday. Hwang didn't respond to a voice message left at his office in Seoul National University and calls to the offices of the Stem Cell Hub weren't answered.

Hwang's work is honored by a South Korean stamp that shows a patient rising from a wheelchair to walk. At the press conference in South Korea last month announcing formation of the bank, researches including the Juvenile Diabetes Research Foundation's Robert Goldstein predicted that stem cells would produce new therapies within five to 10 years.

Hwang has denied reports in the journals Science, where his work was published, and in the British journal Nature suggesting that he paid a lab worker to donate eggs for his research. Schatten has said previously that the South Koreans refuted those reports and that he had believed them.

Unethical

``Regrettably, yesterday information came to my attention suggesting that misrepresentations might have occurred relating to those oocyte donations,'' Schatten said in the statement yesterday. ``I have contacted appropriate academic and regulatory agencies regarding this new information and accordingly, have suspended my collaborations with Prof. Hwang.''

Like paying for organ donations, reimbursing women for egg cells might take advantage of poorer people who might give up valuable tissues for money, Caplan, the University of Pennsylvania bioethicist, said. Lab workers shouldn't be allowed to donate tissue for research, because they might do so under pressure from their superiors, he said.

``If he's engaged in that kind of behavior, and I don't know that it's true, of both using eggs from someone who works for him, and paying her, it's an ethical double whammy,'' Caplan said. ``It will devastate the Koreans; they've turned this guy into kind of a rock star.

Douglas Melton, a Harvard University scientist who is using stem cells to develop treatments for diabetes, said he hasn't evidence that Hwang's work violated any ethical or research rules. If the charges were true, it would be ``disturbing and disappointing,'' he said in a telephone interview yesterday.

To contact the reporters on this story: John Lauerman in Boston at jlauerman@bloomberg.net;

Last Updated: November 12, 2005 23:44 EST