BioEd Online

In the latest chapter of a messy scientific divorce, biologist Gerald Schatten has asked his former collaborator, Woo Suk Hwang, to retract a celebrated stem-cell paper published under both their names.

A statement issued on 13 December by the University of Pittsburgh, Philadelphia, reveals that Schatten has asked to remove his name from a paper that he co-authored with Hwang, of Seoul National University in South Korea, and others.

The paper, published by Science in May, was seen as a major achievement for the field of stem-cell research, because it was the first to show that stem-cell lines could be made from the cells of individual patients¹. Many hoped the work would help scientists to study the origins of disease and investigate treatments tailored to individuals (see ' Korean team lauded for stem-cell advance').

In November, Schatten alleged that some of the actions of Hwang's team were ethically questionable, such as using eggs from paid donors and junior researchers. Hwang later conceded that eggs from such sources had been used during work on a 2004 publication (see ' Clone star admits lies over eggs') .

Now Schatten says he has further concerns: not about the ethics of the research, but about the validity of the results.

Substantial doubts

In a letter he sent to Science and to his fellow authors on 12 December, Schatten, who is director of the Pittsburgh Development Center, writes: "My careful re-evaluations of published figures and tables, along with new problematic information, now casts substantial doubts about the paper's accuracy."

The letter states that over the weekend, Schatten received allegations from someone involved with the experiments that led him to make his decision.

"I request retraction of my co-authorship on Hwang et al. (2005) and have recommended to first author Dr. Woo-Suk Hwang and all other co-authors that the report should now be retracted."

Carbon copies

Schatten's letter does not explain which elements of the 2005 paper he is concerned about.

Some observers, including an anonymous poster to an Internet message board hosted by the Biological Research Information Center, question a DNA fingerprint analysis used to verify the results of the experiments in the 2005 paper. They say the DNA fingerprints from some of the cell lines match the patients' cells too perfectly, and could therefore be duplicates, rather than separate experiments: whether that be accidental or intentional.

Hwang has already told Science that they made an "unintentional error" in providing some duplicate pictures.

On 13 December, Science published a letter on its website from scientists who are calling on Hwang to resolve the matter by cooperating with independent investigators to confirm the results of the DNA tests². The letter is signed by eight scientists, including Ian Wilmut of the University of Edinburgh, UK, who submitted DNA from Dolly, the cloned sheep, to be independently tested.

"As we confirmed the validity of our work by cooperating with an independent study, we encourage Hwang's laboratory to cooperate with us to perform an independent test of his cell lines," Wilmut's letter states.

Pulling out

Science says that it has no mechanism for retracting one author's name from a published paper. "No single author, having declared at the time of submission his full and complete confidence in the contents of the paper, can retract his name unilaterally, after publication, and while inquiries are still underway by the Korean authors," the journal says in an editorial statement issued on 13 December.

Science editor Donald Kennedy says there is no reason to believe the data in the 2005 paper are fraudulent. "We continue to take this issue seriously," Kennedy adds in the statement, "and we are following developments both in South Korea and at the University of Pittsburgh."

Both the University of Pittsburgh and Seoul National University have said they will investigate the work.