Head of Japan's Riken Institute Apologizes Over Stem-Cell Papers

By Alexander Martin 

TOKYO--The head of Japan's Riken science institute on Friday issued an apology over two disputed papers in Nature on stem cells, saying they contained "serious errors."

Ryoji Noyori, a Nobel laureate, bowed deeply at a news conference in Tokyo and said the institute was examining whether to retract the papers.

The lead author of the papers, Haruko Obokata, also issued a statement of apology, joined by co-authors Yoshiki Sasai and Hitoshi Niwa.

"I sincerely apologize for the confusion, and humbly accept the various suggestions made about the flaws in our paper," Dr. Obokata and her co-authors said in the statement. "I am currently contacting other co-authors on the possibility of retracting the papers."

Riken issued an interim report into problems with the papers, which were published in the journal Nature in late January. The report said there were inappropriate elements in parts of the papers that didn't amount to research misconduct. It said more investigation was required for other parts of the papers.

The Nature papers said mouse stem cells could easily be created in a laboratory dish by dipping blood cells into a mild acid solution. If the technique could be adapted to work on human cells, it would promise to transform the treatment for a range of diseases.

But following growing suspicions over some of the images and text used in the studies, one of the co-authors said Monday that he has urged Dr. Obokata to retract the papers. Riken has said, however, that as a general rule, a retraction couldn't be made unless all the authors agree.

Charles Vacanti, another co-author and a tissue engineer at Harvard Medical School and Brigham and Women's Hospital in Boston, has so far defended the paper, saying the questions raised didn't affect the findings of the study.

Earlier Friday, Dr. Obokata offered a defense over some of the allegations made against her.

In an email to The Wall Street Journal, Dr. Obokata responded to suspicions of plagiarism in her dissertation for a doctorate in engineering that she received in 2011 from Japan's Waseda University.

Portions of the document posted online by an anonymous blogger who has been tracking suspicions over the stem-cell studies were almost identical to text posted on a U.S. National Institutes of Health website.

"The doctoral dissertation that is currently making the rounds in the media is not the version that has passed (the university's) screening, but a rough draft," Dr. Obokata told The Wall Street Journal in an email sent early Friday morning.

She said she had reprinted certain text and images in the rough draft. She said that version didn't contain citations or corrections. Dr. Obokata said she has asked the university to retract what she described as the rough-draft version of her dissertation.

A spokesman for Waseda said the university was unaware of such a request and didn't know about any additional versions of the dissertation. The spokesman said the university's investigation into suspicions raised about the dissertation was continuing.

Write to Alexander Martin at alexander.martin@wsj.com