Doubts mount on STAP stem cells

(This story is an update of my earlier blog post on the controversy over whether the stress-created STAP cells actually exist).

A stunning stem cell breakthrough announced last month is being examined for errors by the institute where the studys lead researcher works.

The Riken Institute in Japan has launched an investigation into the study, it told news outlets including the journal Nature, which published the study Jan. 29. The probe was launched after other stem cell researchers, who have failed to replicate the findings, are expressing growing doubt.

The study, led by Haruko Obokata of Riken, found that certain white cells from young mice could be easily converted into embryonic-like or pluripotent stem cells by immersing them in acid or subjecting them to other stresses.

Stem cell researcher Paul Knoepfler / California Institute for Regenerative Medicine

The creation of what the researchers called STAP cells appeared to be a great advance from existing methods used to create what are called induced pluripotent stem cells. The IPS methods require adding genes and chemicals and convert just a small percentage of cells treated.

But scientists examining the study said it apparently used inverted and duplicate images. These included one indicating that the cells grew a placenta, a sure sign that stem cells had been produced. Riken declined to say specifically which allegations it was investigating, according to the news reports.

Additionally, scientists including UC Davis stem cell researcher Paul Knoepfler said the finding appeared very unlikely. Pluripotent stem cells tend to form tumors, so producing them in response to stress should have been weeded out by evolution, Knoepfler wrote on his blog, ipscell.com. Hes also running an informal poll.

Weve had nine people put reports of various kinds there, and none of the reports seemed particularly encouraging, Knoepfler said in a Tuesday interview.

"There's a feeling that the duplication of the placenta image, which now one of the authors has confirmed was indeed a duplication, and also some duplication of data in a paper in 2011 by (co-author Charles) Vacanti and Obokata, has made people more concerned about their level of confidence in the finding overall," Knoepfler said.

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Doubts mount on STAP stem cells