A committee organized by the RIKEN Center for Developmental Biology has concluded that RIKEN’s Haruko Obokata, Ph.D., the lead researcher of a controversial stem cell study, is guilty of scientific misconduct. The study yielded two papers that asserted adult stem cells could be rendered pluripotent by means of external stimuli, such as an acid bath or mechanical stress. However, the results described in these papers, which were published in January 30 in Nature, have not been replicated despite repeated attempts by other research groups. In addition, numerous questions about the original papers have been raised.
The RIKEN committee has thus far confined its investigation to six issues, which were outlined in an interim report issued March 14. These issues concern specific problems with the Nature papers, not whether the researchers’ technique, called stimulus-triggered activation of pluripotency (STAP), is valid. RIKEN has not called for the papers to be retracted, but indicated that it may yet do so, once an appeals process has been completed.
Of the six issues considered, four were dismissed as mere errors. Two, however, were deemed to constitute scientific misconduct. These two issues were described in the interim report as follows:
- Paper 1: “In Figure 1i, lane 3 appears to have been inserted later.”
- Paper 1: “The image of differentiated cells for Figures 2d and 2e and the image of chimera mouse immunostaining data are incorrect, and in the process of the investigation, it was found that these images closely resemble images used by Dr. Obokata in her doctoral dissertation.”
The first item refers to a figure showing an electrophoresis gel. One lane of this gel, Dr. Obokata admits, was swapped for another, but she insists that she was merely showing a clearer version of the lane, not fabricating evidence.
The second item—the use of the same figures to illustrate different studies—concerned the RIKEN investigators because the two studies were so different. In Dr. Obokata’s thesis, the figures were used to illustrate cells that had been stressed with a pipette. In the Nature paper, the figures supposedly showed cells that had been subjected to an acid bath.
Dr. Obokata was not present at the press conference in which she was faulted for misconduct, but she provided a written statement indicating that she does not accept the committee’s findings and intends to appeal. Several researchers on Dr. Obokata’s team were also investigated. Two of them, Yoshiki Sasai, M.D., Ph.D. (still at RIKEN), and Teruhiko Wakayama, Ph.D. (now at Yamanashi University), were not found guilty of misconduct, but they were faulted for failing to adequately check data.
RIKEN indicated that it will set up a separate committee to decide on disciplinary measures. In a written statement, RIKEN also indicated that it will explore ways to prevent recurrences of misconduct, and that RIKEN researchers will continue attempts to replicate the results of the STAP study while also seeking third-party validation.