A respected scientist and coauthor of two high-profile papers that described a controversial technique for creating stem cells has called for the studies to be withdrawn because of what he called serious problems, according to Japanese news reports.
But a Boston researcher who oversaw the work reported in one of the papers said he stands by the key finding that stem cells can be created by dipping mature cells in an acid bath — a method so seemingly simple that it electrified the scientific community when it was published in January.
“I firmly believe that the questions and concerns raised” about the paper “do not affect our findings or conclusions,” Dr. Charles Vacanti, a Brigham and Women’s hospital anesthesiologist who was senior author of one of the papers, said in an e-mail Monday night.
In an interview earlier in the day, he said, “I think there were some simple, perhaps sloppy mistakes that I thought were honest mistakes.”
The cells created with the new technique appear to be similar to embryonic stem cells, which are capable of becoming any of the numerous cell types in the body. Scientists are hoping to eventually develop them into therapies for a range of diseases, from juvenile diabetes to heart failure.
For weeks, the papers published in the journal Nature by a team of Boston and Japanese scientists have been under intense scrutiny, which has revealed possible problems with some of the images and an allegation of plagiarism in the Methods section of one of the papers.
An investigation has been launched by a Japanese research center where many of the authors work, and while the inquiry is ongoing, it has so far stood by the work. The journal Nature is also investigating.
The researcher who is calling for the retraction, Teruhiko Wakayama, is a highly respected scientist best known for his work in cloning mice. His involvement with the papers was one of the key reasons that outside scientists who were skeptical of the stunningly simple method took it seriously.
“I’m no longer sure that the articles are correct,” Wakayama said at a press conference given Monday evening in Japan, according to The Japan News.
Wakayama told another news agency, NHK World, that he is now not sure the stem cells he was given by his coauthors, to check whether they were indeed stem cells that could develop into any cell in the body, were truly created by the technique reported.
“He said he is convinced his experiments were correct, but is no longer sure about the credibility of the data used as preconditions for the experiments,” NHK World reported.
Wakayama told NHK World that his review of data brought to internal meetings of the scientific team that did the research revealed many serious problems. According to The Japan News, he also said that images used in one of the Nature papers look the same as images used in the doctoral thesis of Haruko Obokata, the paper’s lead author.
Wakayama asked the entire team to retract the papers and then have the work reviewed by outside scientists.
“We’d better withdraw our paper, prepare correct data, images, and everything to prove that our paper is right,” he said in a television interview.
In order to retract the papers, all the coauthors would have to sign a retraction agreement — 11 coauthors on one paper and eight on a second paper. According to Nature’s retraction policy, if coauthors disagree about whether a paper should be withdrawn, external peer reviewers would be consulted.
Vacanti said he only learned of Wakayama’s request Monday morning through news reports.
“I’ve not communicated with him yet,” he said. “This is the first I’ve heard of it. I have zero information. . . . I don’t have any information that would make me change my opinion” of the validity of the central findings.
Wakayama did not respond to e-mailed questions.
Last week, the RIKEN Institute in Japan, where many of the scientists involved in the studies work, released a detailed protocol explaining how to make the cells. It was an effort to clarify a situation that has been increasingly murky, because of doubts raised about whether the work was repeatable — an essential step to show a scientific discovery is valid.
Even Wakayama said in a news story in Nature that although he was able to do the procedure successfully once with help from Obokata, he has not since been able to repeat the experiment on his own.
But the protocol itself raised many questions. Paul Knoepfler, a stem cell scientist at the University of California Davis, whose blog has become a resource for information about the technique, described one apparent contradiction with the original paper in the detailed explanation.
Wakayama told Japanese news agencies that the protocol released by RIKEN reported that there was not a change in a gene that had been an important piece of evidence in the original papers that stem cells had been created with the new technique.
“As it has gotten to this more unpleasant, problematic phase, you kind of get the sense there’s not a lot of communication going on” among the authors, Knoepfler said.
It has been confusing for the stem cell science community to sort out the truth about problems with the papers from speculation, which has been rampant, often with pointed critiques occurring in anonymous online forums.
“My sense is he [Wakayama] has sort of lost faith in the overall papers, and again we don’t know what worries him the most,” Knoepfler said.
An investigation into the papers has been ongoing at the RIKEN Institute, where Obokata, the lead author of both of the papers, works. Obokata did not immediately respond to an e-mail.
In a statement, the journal said its investigation is not complete.
“Issues relating to the papers have been brought to Nature’s attention and we are conducting an ongoing investigation. We have no further comment at this stage,” a spokeswoman for Nature wrote in an e-mail.