Reports of Stimulus-Triggered Acquisition of Pluripotency or STAP cells has rocked the stem cell world. If adult cells can be converted into pluripotent stem cells so easily, then perhaps personalized, custom stem cells for each patient are just around the corner.
However, the RIKEN institute, which was heavily involved in the research that brought STAP cells to the world has now opened an investigation into this research, since leading scientists have voiced discrepancies about some of the figures in the paper and others have failed to reproduce the results in the paper.
Last week, Friday (February 14, 2014, spokespersons for the RIKEN centre, which is in Kobe, Japan, announced that the institute is looking into alleged irregularities in the work of biologist Haruko Obokata, who works at the institution. Obokata was the lead author listed on two papers that were published in the international journal Nature. These papers (Obokata, H. et al. Nature 505, 641–647 (2014), and Obokata, H. et al. Nature 505, 676–680 (2014) described a rather simple protocol for deriving pluripotent stem cells from adult mouse cells by exposing them to acidic conditions, other types of stresses such as physical pressure on cell membranes. The cells, according to these two publications, had virtually all the characteristics of mouse embryonic stem cells, but had the added ability to form placental structures, which is an ability that embryonic stem cells do not have. The investigation initiated by the RIKEN centre comes at the behest of scientists who have noticed that some of the images used in these papers might have been duplicated from other papers. Also, several scientists have notes that they have been unable, to date, to replicate her results.
These concerns came to a head last week when the science blog PubPeer, and others, noted some problems in these two Nature papers and in an earlier paper from 2011. Obokata is also the first author of this 2011 paper (Obokata, H. et al. Tissue Eng. Part A 17, 607–15 (2011), and this paper contains a figure that seems to have been used for one of the figures in the 2014 paper. Also, there is another figure duplication.
Harvard Medical School anesthesiologist Charles Vacanti who was the corresponding author of one of the Nature papers has said that has learned last week about a data mix up in the paper and has contacted the journal to request a correction. “It certainly appears to have been an honest mistake [that] did not affect any of the data, the conclusions or any other component of the paper,” says Vacanti. Note that Vacanti is a co-author on both papers and a corresponding author on one of them.
In the other paper, Obokata serves as the corresponding author and this paper contains an image of two placentas that appear to be very similar. Teruhiko Wakayama works at Yamanashi University in Yamanashi prefecture, and he is a co-author on both of these papers. According to Wakayama, he sent more than a hundred images to Obokata and suggests that there was confusion over which to use. He says he is now looking into the problem.
Additionally, ten prominent stem-cell scientists have been unable to repeat Obokata’s results. One particular blog listed eight failures from scientists in the field. However, most of those attempts did not use the same types of cells that Obokata used.
Some scientists think that this could simply be a case of experienced scientists working with a system that they know very well and can manipulate easily, unlike outsiders to this same laboratory. For example, Qi Zhou, a cloning expert at the Institute of Zoology in Beijing, who says most of his mouse cells died after treatment with acid, says that “setting up the system is tricky; as an easy experiment in an experienced lab can be extremely difficult to others, I won’t comment on the authenticity of the work only based on the reproducibility of the technique in my lab,” says Zhou.
However, others are more deeply concerned. For example, Jacob Hanna, a stem-cell biologist at the Weizmann Institute of Science in Rehovot, Israel, however, says “we should all be cautious not to persecute novel findings” but that he is “extremely concerned and sceptical”. He plans to try for about two months before giving up.
It could be that the protocol is far more complicated that thought. For example, even Wakayama has been having trouble reproducing the results. To be sure, Wakayama and a student of his were able to replicate the experiment independently before publication, but only after being coached by Obokata. But since he moved to Yamanashi, he has had no luck. “It looks like an easy technique — just add acid — but it’s not that easy,” he says.
Wakayama says that his own success in replicating Obokata’s results has convinced him that her technique works. “I did it and found it myself,” he says. “I know the results are absolutely true.”
Clearly one way to clear this up is for the authors of this groundbreaking paper to publish a detailed protocol on how to make STAP cells. This should clear up any problems with the papers. Vacanti says he has had no problem repeating the experiment and says he will let Obokata supply the protocol “to avoid any potential for variation that could lead to confusion”.
The journal Nature has said that there are aware of the problems with the papers and looking into the matter.
For now, that’s where the issue sits. Frustrating I know, but until we know more we will have to just “wait and see.”