Last May, a stunning research paper in Science, one of the world's most respected scientific journals, instantly changed the tenor of the debate over cloning human embryos and extracting their stem cells. A team of South Korean scientists reported in the paper that they had figured out how to do this work so efficiently that the great hope of researchers and patients - to obtain stem cells that were an exact match of a patient's - seemed easily within sight.
But that rosy future has been cast into doubt with the statement last month by Dr. Hwang Woo Suk, who led the team that wrote the paper, that it contained fabricated evidence. Questions have also been raised about earlier research and a new debate has begun.
Scientists and ethicists caution that the full story is not in, but they are staggered by how the research has unraveled so far.
"This is a tragic turn," said Laurie Zoloth, director of the Center for Bioethics, Science and Society at Northwestern University. Stressing that she considers Dr. Hwang innocent until proven guilty, she asked, however, whether the edifice of stem cell research was built on sand.
"We depend entirely on the truthfulness of the scientific community," Dr. Zoloth said. "We must believe that what they are showing us and what they say has been demonstrated is worthy of our concern and attention."
The South Korean story, Dr. Zoloth added, raises questions about whether the science is good. "Good as in true and real and morally worthy of our funding," she explained. "That is so most especially in this twilight sort of terrain with a lot of open questions that people disagree about. At least we thought that the step-by-step slow technical achievements had placed the science on a trajectory."
"Is this our version of W.M.D.?" Dr. Zoloth said.
A vocal opponent of cloning human embryos voiced a similar concern. "Certainly, if these reports are true, it's a tragedy for science," said Nigel Cameron, president of the Institute on Biotechnology and the Human Future at the Illinois Institute of Technology.
He said the episode showed that stem cell research and cloning to create human embryonic stem cells, "is a hype balloon and it's been pricked." Not so, said the ethicist Arthur Caplan, an outspoken supporter of stem cell research. "We know that in science, speed kills if you go fast, and that's what the South Koreans did," he said. "It's also clear that they will do whatever it takes to right this ship. At the end of the day, critics of stem cell research will try to use this, but they won't get very far. People bending the rules in other countries doesn't reflect badly on us."
The promise of cloned human embryonic stem cells remains, said Dr. George Daley, a stem cell researcher at Children's Hospital in Boston.
"The goal is still there and the medical value is still largely theoretical but no less than before."
Dr. Cameron, however, said the political implications of the South Korean scandal are huge.
When it seemed that the South Koreans had taken a giant leap forward in stem cell research, he noted, "we panicked into thinking that we have to join in." Politicians and patient groups argued that cures were around the corner if scientists could get the needed support. States poured money into stem cell programs.
The collapsing South Korean claims, Dr. Cameron added, made him ask: "Where's the beef? Where are those cures? Why is it that there is no private money going into this research? The business community values it at zero."
Richard Doerflinger, deputy director of anti-abortion activities at the United States Conference of Catholic Bishops, said that he has argued for some time that the stem cell proponents were exaggerating the state of the science and misleading the public about scientific accomplishments. They promised cures that, if they ever came, would not come any time soon. But Mr. Doerflinger said that when he tried to point out what he saw as misleading claims, " no one would listen."
Now, he said, with the collapse of some of the South Korean scientists' research, the situation may change.
"In one sense, this puts us back to where we were before May of 2005, when there still was some uncertainty about whether this would work at all," Mr. Doerflinger said. "In another sense it does illustrate in my mind how hype and ambition have gotten ahead of the science."
"How am I going to exploit it?" he said. "You don't have to. It's just speaking for itself."
