The South Korean scientist who stunned the world with his claims of cloning human embryonic stem cells has admitted to large-scale fabrication and plans to retract one of his two landmark papers, according to one of his close colleagues.
Roh Sung Il told Korean television and newspapers yesterday that the cloning pioneer, Hwang Woo Suk, told him that most of the embryonic stem cells described in a paper published online in May were not the result of cloning, and that none of the cloned stem cells is living any more. The paper, which Hwang published in the journal Science, claimed that the South Korean team had improved the cloning technique they discovered in 2004, and that they had created 11 different batches of the cells, each with the DNA of a particular patient. In fact, Roh said, at least nine of those batches were not created by cloning.
Hwang responded to the charges today at a packed and televised news conference in Seoul. Although he acknowledged that the cells created for the Science article had since died, he said that he stood by his work and that the breakthrough would be authenticated by tests performed within days.
Other cells, he said, were now being unfrozen and they would prove the veracity of his work.
''Our six research members made 11 stem cells and all confirmed this," Hwang said. ''We six researchers have no doubt."
Hwang said the cells, however, had been badly contaminated by a fungus and he planned to ask prosecutors to investigate his suspicion that they may have been tampered with or replaced.
Hwang said he was retracting the paper from Science because of the uproar, even though he did not doubt his findings. He said a follow-up paper had been submitted to another journal and that would restore faith in his team.
Hwang did not directly address the accusations but said his team had notes and pictures of the process to prove they had made the stem cells. ''I was so surprised and embarrassed to see the news reports," said a combative Hwang.
Roh, head of Miz Medi Hospital in Seoul, did not challenge Hwang's previous paper, in which he claimed to have created the world's first cloned human embryonic stem cells, but scientists said that all of his work, including the first cloned dog, would now be in question.
''Seoul National University will probe doubts raised about [Hwang's] 2005 thesis first and, if the doubts are confirmed, will replicate experiments," the university, where Hwang works, said in a statement read at an earlier news conference today. Roe Jung-hye, the university's dean of research affairs, told reporters the review team would send Hwang's team a questionnaire on Monday and, if it cooperated with the investigation, a conclusion could be reached in one or two weeks.
The news represents a major blow to the field of embryonic stem-cell research. Hwang's team is the only one in the world that has claimed to create cloned embryonic stem cells. These cells can be produced without cloning, but cloned stem cells can be made to have the DNA of a patient with a particular disease, which scientists believe could lead to new insights about a variety of diseases. The South Koreans' apparent success provided hope to other scientists, including two teams affiliated with Harvard that plan to clone human cells themselves. Now it is unclear whether the South Koreans ever cloned human cells -- or whether creating cloned human embryonic stem cells is even possible with current techniques.
''If it is true, it is surprising and tragic," said Douglas Melton, codirector of the Harvard Stem Cell Institute. Melton is part of one team that will attempt to clone human cells, and he said the news would not affect the team's plans. The news, he said, ''should not be allowed to detract from the very closely supervised work going on here and elsewhere."
The disclosures, however, will probably add to the controversy that surrounds government funding of embryonic stem-cell research. One of the arguments that advocates for the research have made is that the South Korean advances show that the United States, which has a more restrictive federal funding policy, was falling behind in this field. Critics have questioned the morality of embryonic stem-cell research, saying that the destruction of human embryos, required for the research, is taking a human life.
''I believe that one of the reasons for this ethical breakdown is the tremendous amount of hype surrounding the embryonic stem-cell field," said the Rev. Tadeusz Pacholczyk, director of education for the National Catholic
A spokesperson for Science said that the journal had not yet received any requests for a retraction from Hwang or his team. Earlier this week, one of the paper's authors, Gerald Schatten at the University of Pittsburgh School of Medicine, asked that his name be removed from the paper, the spokesperson said. Schatten is listed as the paper's senior author, but his contribution is unclear, because the experiments were done in South Korea, under the direction of Hwang.
''My careful reevaluations of published figures and tables, along with new problematic information, now casts substantial doubts about the paper's accuracy," Schatten wrote in his letter to Science. Science has asked Hwang and his coauthors to respond to the allegations raised by Schatten, Roh, and others. The University of Pittsburgh is also investigating.
Human embryonic stem cells have generated tremendous excitement, because they are able to form virtually any type of cell in the body, providing a new way of studying how diseases develop and possibly leading to new treatments. Currently, embryonic stem cell research in this country is done by using frozen embryos -- balls of several hundred cells -- that fertility clinics plan on discarding. These embryos are pulled apart, yielding stem cells.
Cloning, also called somatic cell nuclear transfer, is a technique that allows scientists to create embryonic stem cells that have the DNA of a particular patient. Instead of starting with an embryo, they start with an egg cell donated by a volunteer. The researchers remove the nucleus of the egg cell, which contains its DNA, and then replace it with the nucleus of a cell, such as a skin cell, taken from a patient. This is stimulated to grow. After several days, if forms a ball-like embryo, which is pulled apart, yielding the embryonic stem cells.
For many months, rumors have swirled around the Korean team, with allegations that they had used egg cells from junior scientists in their own laboratory, a practice that is frowned on because the scientists might feel pressured to undergo the egg donation procedure, which involves some risk to the donor.
The allegations gained momentum last month when Schatten, who was helping Hwang and his team set up an international consortium to share cloning technology, abruptly pulled out of the consortium. Hwang then admitted that he had lied about the sources of the eggs, which included a junior researcher and eggs that were purchased by Roh. Hwang also said there were several technical problems with the May paper that did not undercut the basic scientific findings, such as photographs that were inadvertently duplicated.
Then, on Tuesday, Schatten asked to be removed from the manuscript entirely, and called on his coauthors to retract it.
Roh said in television appearances yesterday Hwang told him some stem-cell lines were indeed created through cloning but were later contaminated and destroyed. Hwang then took embryonic stem cells from Roh's laboratory, which had nothing to do with Hwang's research, and claimed they had been created through cloning, Roh said Hwang told him.
Roh said he first learned of Hwang's alleged fabrication from another coauthor of the paper who was ordered by Hwang to help fabricate data to make it appear that there were 11 stem-cell colonies. Roh confronted Hwang. Hwang confessed to a ''crushing humiliation" and said he was sending a letter to Science retracting the paper, the Hankyoreh daily newspaper quoted Roh as saying.
Material from the Associated Press, the International Herald Tribune, and Reuters was used in this report. Gareth Cook can be reached at firstname.lastname@example.org.