Haruko Obokata, who had led the studies, was solely responsible for the misconduct, Riken’s investigation committee said in documents provided at a Tokyo briefing today. Co-authors Teruhiko Wakayama at University of Yamanashi and Yoshiki Sasai at Riken bear “heavy responsibility” for allowing the papers to be submitted to the journal Nature without verifying the accuracy of the data, the committee concluded.
Government-funded Riken on March 11 said it was investigating the two studies that were published in Nature in January and had said that ordinary cells taken from newborn mice could be transformed into stem cells without adding genes. Out of six figures and images an investigation committee reviewed, two were falsified or faked, Riken said today.
Obokata said the errors found by the committee in the stem-cell studies were mistakes made without malicious intent, according to a statement distributed at a Riken briefing today. The scientist said she can’t accept its conclusion that the data were falsified and will file a complaint to Riken soon. Obokata didn’t immediately respond to a separate e-mailed request for comment on the Riken findings today.
In one section, Obokata created an composite image from two separated images using her own experimental data to show a clearer picture, the committee report said. Other images used to show the pluripotency of the stem cells resembled pictures in her doctoral thesis, which used different criteria for experiments, it said. Traces of the images suggest they were cut out from an identical arrangement of images in the doctoral thesis, it said.
If misconduct is confirmed following the appeals process, the papers in question should be retracted, said Ryoji Noyori, head of Riken and Nobel Prize winner for chemistry in 2001. Riken will impose a penalty based on a review by its disciplinary committee, he said.
Sasai said he is “deeply regretful” the studies were found to have errors, in a statement given at the briefing. He said he wasn’t aware of the errors before they were published in the journal. The data were highly consistent with other experiments and there were limitations on noticing and correcting them, he said. Wakayama said he feels guilty he failed to see errors in the studies in a separate statement.
Riken has set up a team and will spend a year from today conducting a study to check the validity of the studies and give an interim report after four months, it said.
The institute on March 14 said it was examining images and methods in the research after claims that they looked unnatural or were plagiarized from other studies and apologized for errors. At that time Obokata and two other Riken researchers in a statement on the center’s website had said they were in talks with co-writers to discuss a retraction.
The probe is a setback for Japan as it tries to push into stem-cell science following Shinya Yamanaka’s 2012 Nobel Prize. Japan aims to cement its leadership in the field of research, and has pushed through bills that fast-track regulatory approval for cell-based products.
Researchers led by Obokata at the Riken Center for Developmental Biology shocked the cells with a dose of “sublethal stress” such as mechanical force to trigger a transformation. Obokata worked with institutions including Charles Vacanti’s laboratory at Brigham and Women’s Hospital, Harvard Medical School.
In an embryo’s early stages, stem cells are pluripotent, meaning they can become any type of tissue in the body. As the embryo develops, the cells begin to specialize, or differentiate, into units for the body’s different structures.
There are several ways to regenerate pluripotent stem cells, including one that uses embryos and one that reprograms matured cells by inserting genes. Last year, Japan’s Health Ministry cleared the way for the world’s first clinical trial with stem cells made using a separate technique established by Yamanaka, the Nobel Prize winner from Kyoto University.
In 2004, South Korean researcher Hwang Woo Suk published a study claiming to have created stem cells from DNA placed into a donor egg. The study and a follow-up turned out to be faked, a 2006 Seoul National University investigation found.
South Korea banned studying stem cells using human embryos for three years on the scandal.
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