TOKYO Aug 5 A Japanese researcher at the centre
of discredited research that was initially hailed as a potential
breakthrough for stem-cell treatment, killed himself after
months of stress and exhaustion, officials said on Tuesday.
Yoshiki Sasai, co-author of the high-profile research that
had seemed to offer hope for replacing damaged cells or even
growing new human organs, was found early on Tuesday at the
Riken institute where he worked in Kobe, western Japan, police
and the institute said.
"It is confirmed as a suicide," said a police spokesman. "It
was a hanging."
Sasai, 52, had been hospitalized in March for stress and
become less receptive to media inquiries during the controversy
over the team's research, said Riken spokesman Satoru Kagaya.
The scientist "had seemed completely exhausted" in their
last phone conversation around May or June, Kagaya told a
televised news conference.
As deputy director of Riken's Center for Developmental
Biology, Sasai supervised the work of lead author Haruko
Obokata, which took the world of molecular biology by storm when
it was published in the British journal Nature in January.
It was retracted after months of controversy that made
front-page news in Japan and tarnished the country's reputation
for scientific research.
"It is very unfortunate that this happened," said the
government's top spokesman, Chief Cabinet Secretary Yoshihide
Suga. "Mr Sasai contributed greatly in the field of
developmental biology and was an internationally renowned
Riken president Ryoji Noyori expressed "deep regret over the
loss of an irreplaceable scientist."
In what looked like game-changing discovery, Obokata, Sasai
and the other authors described simple ways to reprogramme
mature animal cells back to an embryonic-like state, allowing
them to generate many different types of cells.
But questions soon arose about the research, as other
scientists could not replicate the startling claims. Riken said
its investigation found Obokata had plagiarized and fabricated
parts of the papers, raising doubts about the credibility of
After defending her work for months against Riken's claims,
Obokata agreed in June to retract the papers, which Nature did
in early July.
Despite the retractions of the research papers, Sasai never
wavered in his belief that Stimulus-Triggered Acquisition of
Pluripotency, or STAP, cells could exist, Japanese media said.
Obokata was "very shocked" at Sasai's suicide and was being
assisted by two Riken staffers, Kagaya said.
Sasai left five suicide notes, including two addressed to
senior Riken officials, he said. He would not disclose the
contents or to whom the other letters were addressed.
Sasai started receiving counselling in April and recently
had trouble communicating due to side-effects of medical
treatments he was undergoing, media reported.
(Reporting by Megumi Lim; Additional reporting by Kaori Kaneko;
Editing by William Mallard and Robert Birsel)