The retractions of the two reports, which were written by South Korean cloning researcher Hwang Woo-suk and his colleagues, were a foregone conclusion in the wake of Tuesday's findings from an investigative panel at Seoul National University, where Hwang had worked. That panel found that Hwang's claims to have created new lines of human embryonic stem cells from cloned embryos were based on fabricated data.
Hwang himself apologized for the fraud during a Seoul news conference on Thursday, although he contended that he was a victim rather than the perpetrator. He insisted that his lab could create patient-specific stem cells in six months, as he originally claimed, as long as enough human eggs were made available.
Thursday's retraction covered the Science paper on patient-specific stem cells, published in May 2005, as well as a 2004 paper reporting that stem cells had been isolated from one cloned human embryo.
"Because the final report of the SNU investigation indicated that a significant amount of the data presented in both papers is fabricated, the editors of Science feel that an immediate and unconditional retraction of both papers is needed," the journal said in a statement attributed to editor-in-chief Donald Kennedy and published on its Web site (PDF file). "We therefore retract these two papers and advise the scientific community that the results reported in them are deemed to be invalid."
The journal said it had received agreement to the retraction from six of the 15 authors listed for the 2004 paper, and from all 25 authors of the 2005 paper. Science also said it regretted "the time that the peer reviewers and others spent evaluating these papers as well as the time and resources that the scientific community may have spent trying to replicate these results."
The stem cell scandal has led Science to consider changes in its peer-review procedures. Kennedy told reporters last month that he wasn't sure the review process could have detected the fraud in advance of publication. Some observers have suggested that laboratories might have to provide outside verification of high-profile results.
Hwang's original claims were so breathtaking — and his fall from grace was so steep — because the creation of tailored stem cells appeared to represent a giant leap in the field. Tailored stem cells would have opened new options for studying human diseases in the lab, and eventually might have led to new cures for maladies ranging from spinal-cord injuries to heart disease and Parkinson's disease.
Stem cells are the master cells involved in regenerating body tissues, and embryonic stem cells could theoretically be transformed into virtually any type of tissue. The field is controversial, however, because human embryos — produced either through in-vitro fertilization or cloning — are destroyed in the process of extracting the cells. Opponents of the research say that adult stem cells, cord-blood cells or reprogrammed cells could produce much of the therapeutic value of the embryonic cells, without the ethical problems.
Researchers have said studies of human embryonic stem cells would continue despite the South Korean fraud. Indeed, shortly after Hwang's 2005 paper was published, a British team said they had succeeded in producing a cloned human embryo, although no stem cells were extracted in that case.
In addition to his now-discredited work with human stem cells, Hwang has conducted research into animal cloning — and the university panel said that his claim of having produced a cloned dog named Snuppy, published last August in the journal Nature, appeared to be genuine. This week, Nature's editors told reporters that outside tests had indeed confirmed that feat.