The research — hailed when it came out in January as a
breakthrough that could herald a new era of medical biology — was
covered widely in Japan and across the world after it was published
in the highly reputable science journal Nature.
But since then, there have been reports that other scientists have
been unable to replicate the Japanese team's results and that there
may have been problems with its data and images.
"It is no longer clear what is right," Teruhiko Wakayama, a
professor at Japan's University of Yamanashi who was part of the
researcher team, told public broadcaster NHK.
The study, described as game-changing by independent experts asked
to comment on it when it was published, appeared to show a simple
way to reprogram mature animal cells back into an embryonic-like
state that would allow them to generate many types of tissue.
The results appeared to offer a promise that human cells might in
future be simply and cheaply reprogrammed back into embryonic
cell-like cells — in this case cells dubbed Stimulus-Triggered
Acquisition of Pluripotency, or STAP, cells — suggesting a simple
way to replace damaged cells or grow new organs for sick and injured
"When conducting the experiment, I believed it was absolutely
right," Wakayama said.
"But now that many mistakes have emerged, I think it is best to
withdraw the research paper once and, using correct data and correct
pictures, to prove once again the paper is right. If it turns out to
be wrong, we would need to make it clear why a thing like this
A Nature spokesperson said "issues relating to this paper" had been
brought to the journal's attention and it was conducting an
investigation, but made no further comment.
Robin Lovell-Badge, a stem cell expert at Britain's National
Institute for Medical Research, cautioned against premature
assumptions on whether the research was flawed.
"I have an open mind on this," he told Reuters. "I'm waiting to hear
from several serious stem cell labs around the world on whether they
have been able to reproduce the methods."
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Wakayama's co-researcher Haruko Obokata, became an instant celebrity
in Japan after she spoke during a Nature media briefing to science
reporters all over the world about her eye-catching findings.
Japanese researchers, joined by others from Brigham and Women's
Hospital and Harvard Medical School in the United States, took skin
and blood cells, let them multiply, then subjected them to stress
"almost to the point of death", they explained, by exposing them to
various events including trauma, low oxygen levels and acidic
One of these "stressful" situations was simply to bathe the cells in
a weak acid solution for around 30 minutes. Within days, the
scientists said they had found that the cells had not only survived
but had also recovered by naturally reverting into a state similar
to that of an embryonic stem cell.
Yet no other research team has yet been able to replicate the
findings, and the RIKEN Center for Developmental Biology in Japan,
where Obokata works, said last week it had "launched an independent
inquiry into the content of the paper.
That inquiry would be conducted by a panel of experts from within
and outside RIKEN, it said, and would be published as soon as it was
A RIKEN spokesman declined to comment on Wakayama's call for the
paper to be withdrawn.
(Additional writing by William Mallard;
editing by Nick Macfie and
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