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Just weeks after invalidating a groundbreaking paper describing a simple technique for generating pluripotent stem cells, professor Kenneth Ka Ho Lee now believes he has identified the correct approach.

Lee, chief of stem cell research at the Chinese University of Hong, spoke to Wired.co.uk in March about his tentative excitement when he read the Nature study in question, published at the start of the year. The proposed Stap cells (stimulus-triggered acquisition of pluripotency) in it were a revelation, because they suggested there was a simple way to generate embryonic-like stem cells that could potentially be used in the treatment of diseases such as Parkinson's. The method involved reprogramming a donor's own adult blood and skin cells (in this case, mice) by exposing them to extreme trauma, such as an acid bath.


Lee could see its potential, but like the rest of the community he had his doubts. While reports circulated that the images published in the Nature study also featured in older papers penned by lead researcher Haruko Obokata of Japan's Riken Centre, Lee set about trying to replicate the experiment himself.

It didn't work.

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Since then the Riken Centre has launched an investigation into the legitimacy of the trial, and that investigation today revealed Obokata had indeed falsified information, including results and images of DNA fragments used. "Actions like this completely destroy data credibility," commented Shunsuke Ishii, head of the investigative committee and a Riken molecular geneticist, at a press conference. "There is no doubt that she was fully aware of this danger. We've therefore concluded this was an act of research misconduct involving fabrication." Obokata has denied the allegations, but Riken says its own research team will be the one to verify the results and carry out the experiment again.

In the interim however, a coauthor on the paper at the centre of the debacle, Charles Vacanti published yet another protocol for the Stap technique, fairly different from the original. Vacanti, of ear-on-a-mouse fame, is a professor at Harvard Medical School and published online what he said was found to be "an effective protocol for generating Stap cells in our lab, regardless of the cell type being studied". It was a combination of the two approaches mentioned in the Nature paper -- the acid bath, and the trituration process (the application of pressure on the cells using pipettes to induce stress). He describes the latter process as being exerted with force, more so than in the original paper, and over a lengthy period -- twice a day for the first week.


Kenneth Lee

Nature had already rejected Lee's version of experiments for publication last month. Undeterred, he set about applying Vacanti's technique. Liveblogging the experiments on ResearchGate, the open source platform where Lee had published his first set of experiments, the Hong Kong researcher immediately saw the excess stress was leading to rapid cell death among the lung fibroblast cells used. "The Vacanti protocol put a deal of emphasis on mechanically passing the cells through narrow bore glass pipettes for 30 minutes before acid treatment and then growing the cells on non-adhesive culture plates," Lee told Wired.co.uk. "We conducted these experiments, but it did not induce expression of the pluripotent stem cell markers (Oct4, Sox2 and Nanog)."

Nevertheless, things appeared to turn around. In his preliminary studies Lee has concluded that it could be the extreme stress through trituration, and not the acid bath, that was responsible for creating the Stap cells. "To our surprise, our negative control of mechanical triturating the cells only, but no acid bath, induced the expression of these three stem cell markers. It was April Fools Day, so I thought my students were pulling my leg. But the results seem to check out.


Therefore, there is a very slim chance that these cells could be stem cells or the bi-product of un-regulated gene expression by dying or stress cells. Clearly more experiments have to done." "I am not claiming Stap cells exist because the result that I posted on ResearchGate is very early. I have followed Vacanti's protocol, which was very different to the one used by Obokata."

Lee, however, will most likely not be the one to carry out these future studies. He says he would be reluctant to do so, considering how he has become something of "an advocate" for Stap cells in the media, which he insists he is not. "I am sure this information will help other laboratories to try and see whether mechanical trituration rather than acid bath will work in inducing stem cells."

Update: This article was updated to include comment from Kenneth Ka Ho Lee.