Post by Admin on Mar 25, 2015 13:44:04 GMT
In her first appearance before the press since her claims of an astounding breakthrough in stem cell research started unraveling, Haruko Obokata, of the RIKEN Center for Developmental Biology in Kobe, Japan, apologized for the trouble she has caused her employer, her colleagues, and the scientific community. But she also firmly maintained that STAP cells, the new type of stem cells she claims to have developed, exist, and said she will not retract the two Nature papers reporting her finding.
“I sincerely apologize to RIKEN, my co-authors, and to many others for the trouble I caused through my insufficient experience and carelessness," Obokata said with a deep bow at the beginning of the press conference, which was held in Osaka. But "STAP cells exist!" she defiantly declared in response to a question. She also pledged to "go anywhere" to help any interested scientist reproduce her results.
Obokata last faced the press when she and colleagues at RIKEN and other institutions in Japan and at Harvard Medical School in Boston published a research article and a letter online in Nature on 29 January. The 30-year-old was lionized in Japan for her unexpected breakthrough, a method to create stem cells that she called "stimulus-triggered acquisition of pluripotency," or STAP. It works by subjecting mature cells to a brief acid bath and then tweaking culture conditions. But soon there were reports of doctored images and plagiarism, and to date, no one has reported replicating the first step in creating STAP cells. One co-author has called for the papers to be retracted.
Within weeks, scientific bloggers identified problematic images. Soon, researchers around the world reported being unable to reproduce the results. RIKEN launched an investigation and by April concluded that Obokata was guilty of research misconduct. Nature retracted the papers in July. Despite numerous problems in the papers, Obokata and co-author Charles Vacanti, a BWH tissue engineer, staunchly maintained that the STAP phenomenon was real and kept releasing tweaks to their published protocols. RIKEN officials decided to settle the issue by methodically redoing the experiments described in the papers. In an interim report released in August, the verification team reported not being able to produce STAP cells. At that time, the team invited Obokata to participate in their efforts to see if there were subtleties in her experimental techniques not defined in her published protocols.
A RIKEN investigating committee announced on 1 April that it had found two instances of research misconduct. RIKEN President Ryoji Noyori said at the time that Obokata would be given a chance to appeal before a disciplinary committee would be convened. Obokata's lawyers filed the appeal with RIKEN yesterday.
At the press conference, Kazuhiko Murotani, one of her attorneys, elaborated on Obokata’s previous claims that there was no intent to deceive, and that the problems in the papers do not affect the results. He did reveal a few new details. For instance, Obokata had previously admitted to using images from her doctoral thesis in the Nature papers by mistake; Murotani explained today that the images did not come directly from the thesis, but rather resulted from a mix-up of PowerPoint slides.
She apologized several times for the errors in the papers, but also repeatedly expressed her faith in her findings. She claimed she has created STAP cells more than 200 times; retracting the Nature papers would indicate that the STAP phenomenon is not real, she added. "If I can continue in research, I want to work to realize the hopes of STAP cells as quickly as possible," she said.
Several critical errors have been found in our Article (http://dx.doi.org/10.1038/nature12968) and Letter, which led to an in-depth investigation by the RIKEN Institute. The RIKEN investigation committee has categorized some of the errors as misconduct (see Supplementary Data 1 and Supplementary Data 2). Additional errors identified by the authors that are not discussed in RIKEN’s report are listed below.
(1) Figure 1a and b in the Letter both show embryos generated from STAP cells, not a comparison of ES- and STAP-derived chimaeric embryos, as indicated in the legend.
(2) Extended Data Fig. 7d in the Article and Extended Data Fig. 1a in the Letter are different images of the same embryo and not, as indicated in the legends, a diploid chimaera embryo and tetraploid chimaera embryo.
(3) There is an erroneous description in Fig. 1a in the Letter. The right panel of Fig. 1a is not a ‘long exposure’ image at the camera level but a digitally enhanced one.
(4) In Fig. 4b of the Letter, STAP cell and ES cell are wrongly labelled in a reverse manner.
(5) In the Article, one group of STAP stem cells (STAP-SCs) was reported as being derived from STAP cells induced from spleens of F1 hybrids from the cross of mouse lines carrying identical cag-gfp insertions in chromosome 18 in the background of 129/Sv and B6, respectively, and that they were maintained in the Wakayama laboratory. However, further analysis of the eight STAP-SC lines indicates that, while sharing the same 129×B6 F1 genetic background, they have a different GFP insertion site. Furthermore, while the mice used for STAP cell induction are homozygous for the GFP transgene, the STAP-SCs are heterozygous. The GFP transgene insertion site matches that of the mice and ES cells kept in the Wakayama laboratory. Thus, there are inexplicable discrepancies in genetic background and transgene insertion sites between the donor mice and the reported STAP-SCs.
We apologize for the mistakes included in the Article and Letter. These multiple errors impair the credibility of the study as a whole and we are unable to say without doubt whether the STAP-SC phenomenon is real. Ongoing studies are investigating this phenomenon afresh, but given the extensive nature of the errors currently found, we consider it appropriate to retract both papers.
Nature 505, 676–680 (2014); doi:10.1038/nature12969