This photo taken on January 28, 2014 shows Japanese researcher Haruko Obokata (L) of the Japan-based Riken Institute and Yamanashi University professor Teruhiko Wakayama (R) displaying a picture of stem cells during a press conference at a Riken research center in Kobe, western Japan. Wakayama, the co-author of a Japanese study that promised a revolutionary way to create stem cells, has called on March 11, 2014 for the headline-grabbing research to be retracted over claims its data was faulty. JAPAN OUT AFP PHOTO / JIJI PRESSJIJI PRESS/AFP/Getty Images
Japanese researcher Haruko Obokata (left) of the Japan-based Riken Institute and Yamanashi University professor Teruhiko Wakayama displaying a picture of stem cells during a January press conference.
JIJI PRESS/AFP/Getty Images

A Japanese research institution plans to make an announcement Friday about its investigation of two highly controversial stem cell studies authored by Boston and Japanese scientists. That announcement comes as more doubt has been cast on the papers, which reported that stem cells could be created by dipping mature cells in an acid bath—a surprisingly simple technique that stunned scientists.

On Monday evening in Japan, a coauthor of both papers announced he no longer had confidence in the findings due to problems that have emerged with images and data. The scientist, Teruhiko Wakayama, urged his Boston and Japanese coauthors to withdraw the papers published in the journal Nature in January and to redo the experiments so that they could be meticulously reviewed.

A Japanese website that has been posting critiques of the paper also published images from the lead scientist’s doctoral thesis that appear strikingly similar to ones that appeared in one of the controversial papers. It also posted a 22-page portion of the thesis by Haruko Obokata that appears virtually identical to a National Institutes of Health website describing stem cells.

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Dr. Charles Vacanti, an anesthesiologist at Harvard-affiliated Brigham and Women’s Hospital who was senior author of one of the papers and supervised Obokata when she began working in his lab in 2008 while pursuing her graduate degree from a Japanese University.

He has said repeatedly that he stands behind the work and that the problems he was aware of thus far appear to be honest mistakes. He did not immediately respond to an e-mail on Wednesday.

In a statement released Wednesday, RIKEN, the Japanese research institute where Obokata and many of her coauthors work, said that the alleged problems were being reviewed and that a retraction is being considered.

“RIKEN takes very seriously the new concerns that have been raised regarding the use of images from Dr. Obokata’s doctoral dissertation in the papers published in Nature, and has launched an investigation. We will ascertain the facts before drawing our conclusions and will issue a report at the appropriate time,” the RIKEN statement said. “While the investigations are still in progress, the credibility of the papers have been brought into question, and from the perspective of research ethics, RIKEN is considering the possibility of retracting the two papers published in Nature.”

A spokesman for Harvard Medical School would not disclose whether there are plans to launch an internal investigation of the work. In general, the institution has not confirmed or denied the existence of investigations when questions have been raised about other scientific research.

“We are fully committed to upholding the highest standards of ethics and to rigorously maintaining the integrity of our research. Any concerns brought to our attention are thoroughly reviewed in accordance with institutional policies and applicable regulations,” Harvard said in a statement.

Outside stem cell scientists have said that the developments are concerning, but that they don’t know what to make of the situation. Wakayama is a prominent and respected scientist, and his involvement in the work was a chief reason that many stem cell scientists took the finding seriously. He was a co-author on one paper and a senior author on a second paper, and his unusual announcement that he no longer had faith in the result was seen as significant.

In an interview with the Japanese newspaper Yomiuri Shimbun, Wakayama said on Tuesday that, “I think senior officials at RIKEN regard the mistakes as almost fatal.”

Scientists have had trouble in repeating the experiments, including Wakayama himself, which has heightened skepticism.

An e-mail inquiring about the questions raised about Obokata’s thesis to Masayuki Yamato, a professor at Tokyo Women’s Medical University who advised Obokata as a master’s student, was not answered.

But in an earlier e-mail exhange, before problems with the paper had been revealed, Yamato described his role in the research:

“I was a mentor of Haruko from her master course. Therefore, I have checked her all [her] data obtained in Boston,” Yamato wrote in an e-mail to the Globe.

He said that he and Vacanti independently reached the same conclusion when reviewing Obokata’s work:

“I was completely convinced,” Yamoto wrote, that the stem cells isolated in Obokata’s experiments were “created” through the acid-bath procedure. “I was so surprised to find that Chuck and I had independently reached the same conclusion, based on our Haruko’s data.”