Stem-Cell Scientist Linked With Retracted Studies Dies

A prominent Japanese scientist who was a co-author on stem-cell research that was retracted last month died today in the city of Kobe, local police said.

Yoshiki Sasai, deputy director of Riken’s Center for Developmental Biology, was found hanging at the center and his death was confirmed at 11:03 a.m. at a hospital, according to a spokesman for the Hyogo Prefectural Police who asked not to be identified because of the agency’s rules. Sasai left an apparent suicide note on the desk of his secretary, Jun Nonaka, a spokesman at Riken, said by telephone today.

Sasai was one of the co-authors of a pair of stem cell studies published in the journal Nature in January that outlined a simpler, quicker way to make stem cells. In July, Nature confirmed the retraction of the two studies, which had said ordinary cells taken from newborn mice could be transformed into stem cells without adding genes.

The studies, led by Haruko Obokata at Riken, were retracted after an investigation by the research center showed she falsified some data and was solely responsible for the misconduct. Co-authors Teruhiko Wakayama at University of Yamanashi and Sasai at Riken bear “heavy responsibility” for allowing the papers to be submitted to the journal Nature without verifying the accuracy of the data, Riken said in April.

Obokata’s lawyer Hideo Miki declined to comment on Sasai’s death and said he has no plan to issue a statement. Wakayama didn’t immediately respond to an e-mail seeking comment.

Sasai, who graduated from Kyoto University in 1986, was a stem-cell biologist and is known for his work on coaxing stem cells to grow into different tissues, such as for brains and eyes. His studies led his colleague Masayo Takahashi at Riken to run the world’s first clinical trial in humans with stem cells made using the Nobel Prize-winning technique of Shinya Yamanaka.

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