Posted on behalf of David Cyranoski

Haruko Obokata, the Japanese scientist at the centre of a controversy over studies purporting to turn mature cells to stem cells simply by bathing them in acid or subjecting them to mechanical stress, today apologized for her errors in the work.

Kicking off a press conference in Osaka amid a storm of snapping cameras and flanked by two lawyers, Obokata blamed her immaturity and her lack of awareness of research protocols for the errors that were found in her two high-profile papers on the studies, published in Nature in January (Note: Nature’s news and comment teams are editorially independent of its research editorial team). These included the use of a duplicated image.

She took full responsibility for the errors, and apologized to her co-authors for the mess she got them into. Obokata, in her first public statement in more than two months, also apologized to her institute, the RIKEN Center for Developmental Biology, for the embarrassing press the whole ordeal had brought. In addition, she sought forgiveness from the RIKEN committee whose report earlier this month found her guilty of scientific misconduct. She had attacked the report at the time.

Obokata held the press conference for two reasons: to apologize for the errors and to make the case that her research was still valid and that the inaccuracies in the papers were not deliberate. Yesterday, she submitted a formal appeal to RIKEN that their committee retract its misconduct findings. She insisted that the “stimulus-triggered activation pluripotency” or STAP phenomenon, as it has been dubbed, exists. RIKEN has 50 days to respond to her appeal.

In the STAP work, lead author Obokata, along with Japanese and US colleagues, described stunning experiments in which she reprogrammed mature mouse cells to an embryonic state merely by stressing them. But the two papers soon fell under suspicion and last month a RIKEN-appointed investigative committee found in a preliminary report that they contained numerous errors. In a further report on 1 April, the committee announced that two of the errors constituted scientific misconduct. On the same day, Obokata responded aggressively, with a written statement expressing “shock and anger” at conclusions she said had been reached without giving her a chance to explain herself. Today, her tone was very different: pleading for forgiveness and showering apologies. But she maintained that her findings hold true.

Obokata insisted that the two problems which led to the misconduct findings — the duplicated image and the swapping of a diagram of an electrophoresis gel — were only errors. She said she had not been given enough time to explain her side to the committee.

After her five plus minutes of introductory remarks, her lawyer gave a 20-minute presentation to make the case that neither problem added up to misconduct. Defining fraud as fabrication, he countered that in both cases Obokata had the original data that should have been used but merely added the wrong data by mistake. For the more damning finding — an image of teratomas that had appeared in her doctoral dissertation and then again in the recent papers — the committee had found that she had changed a caption, which made it look intentional. The lawyer however traced the image back to a slide, part of a presentation that Obokata had continually updated and reused, until its origin became obscured. (Later, in one of her many apologies, she said, “If I had gone back to carefully check the original data, there wouldn’t have been this problem.”)

After the lawyer’s talk, Obokata responded to journalists’ questions for more than 2 hours. In response to suspicions based on the fact that she only handed two laboratory notebooks over to the committee looking into her research, she said she had four or five more that the committee hadn’t requested. She denied that she ever agreed to retract the papers. She also corrected reports that she had asked to retract her PhD dissertation, saying that she merely sought advice on how to proceed. Her dissertation is under investigation at Waseda University, where she studied for her doctorate.

Obokata also denied the possibility that the STAP cells had resulted from contamination from embryonic stem cells, saying that she had not allowed embryonic cells in the same laboratory and that she had carried out tests which precluded that possibility.

She said that she had created STAP cells more than 200 times, adding that she knows someone who has independently achieved it but refused to give the name (citing privacy). She believes that a RIKEN group trying to demonstrate STAP cells will help her. She has not, she said, been asked to participate in those efforts. She added that she would consider doing a public replication experiment but that it was not up to her whether she could.

Two hours into the questioning, her lawyer cut off journalists, citing concern for Obokata’s frail emotional state, and said she had to return to the hospital where she has been staying. She bowed, apologized, then bowed again and left. The press cameras contined to snap away.