Skip to content

Royan Institute

  Home arrow News arrow International News arrow Japanese Stem-Cell Scientist Yoshiki Sasai Commits Suicide
Japanese Stem-Cell Scientist Yoshiki Sasai Commits Suicide PDF Print E-mail
TOKYO—A top Japanese scientist who co-authored disputed stem-cell papers committed suicide by hanging himself, police said Tuesday.
Yoshiki Sasai, deputy director of the Riken Center for Developmental Biology, guided research published in the journal Nature that purported to show a revolutionary method of creating stem cells by dipping cells in a mild acid solution. The research, published in January, was quickly challenged. Nature retracted the papers in July, saying they contained inaccurate data and other flaws that undermined their conclusions.

Dr. Sasai, 52, was found by a security guard Tuesday morning in a biomedical research institution adjacent to the Riken center in Kobe, western Japan, Riken said. Apparent suicide notes were found on his secretary's desk, as well as at the scene, it said.
A respected scientist and expert on embryonic stem cells, Dr. Sasai worked closely with lead author Haruko Obokata on the two stem-cell papers published in Nature. He said he was asked to join the research project in its final stage and was mainly responsible for editing and revising the papers.
At a news conference in April, Dr. Sasai said that while he believed the papers should be retracted in light of the problems, some data couldn't be explained without assuming the existence of the new kind of stem cell. He said he continued to believe there were promising signs of a breakthrough.
Stem cells can turn into a variety of tissue cells and are being studied for possible applications in treating heart disease, diabetes and other ailments.
The controversy has put the reputation of Riken, one of Japan's leading research institutions, at risk. Starting in July, Riken allowed Dr. Obokata to conduct experiments aimed at verifying the existence of the special stem cells. Outside scientists haven't been able to replicate the results, and Riken said a separate investigative team would conduct verification experiments as well.
Dr. Obokata's lawyer told reporters that he was very surprised to hear of Dr. Sasai's death but couldn't comment further. As of Tuesday night, Dr. Obokata hadn't responded to an email seeking comment.
Riken president and Nobel laureate Ryoji Noyori said in a statement that he was stunned by the news and deeply regretted the loss of a researcher "invaluable to the global scientific community."
Science writer Shinya Midori said Dr. Sasai was an international authority in studies on turning stem cells into various organs. In a 2011 study, his team coaxed mouse cells to form a retina—a technique that promised to pave the way for treatments of eye diseases if it could be adapted to human cells.
Born in 1962, Dr. Sasai studied at the Kyoto University School of Medicine and earned his Ph.D. from the institution in 1993. After working as a professor at the university, he moved to Riken's developmental-biology center in 2003. He was promoted to deputy director of the center last year.
The government's top spokesman, Yoshihide Suga, said Dr. Sasai made significant achievements in the field of regenerative medicine.
Dr. Sasai's career took a heavy blow from the controversy over the Nature studies. Once considered a likely candidate to lead the Riken developmental-biology center, he instead faced the prospect of disciplinary action. In an email exchange with The Wall Street Journal in April, Dr. Sasai said he was "overwhelmed with shame" for what he described as his failure in adequately supervising the research. Colleagues of Dr. Sasai have described him as a dedicated and precise researcher with good leadership skills.
A Riken official briefing reporters Tuesday afternoon said Dr. Sasai had recently appeared "both physically and mentally exhausted."
A 2012 Nature article described Dr. Sasai as "a bit stiff in movement and reserved in manner," but said he "nevertheless puts on a theatrical show with a cocktail shaker at parties held by his institute after international symposia."

Main Menu