A Riken panel reports that the cells supposedly returned to a pluripotent state using the now discredited stimulus-triggered acquisition of pluripotency (STAP) approach were actually derived from embryonic stem cell lines, according to ScienceInsider.
The Nature papers describing the approach were retracted in July, and Haruko Obokata, the lead author on the work, recently resigned after the technique couldn't be replicated. Another Riken panel had found her guilty of research misconduct, citing image manipulations and data re-use.
This report, ScienceInsider says, found that the STAP stem cells and the mice chimeras and teratomas that were purportedly derived from them actually came from cultures that contaminated with three different embryonic stem cell lines. The panel, ScienceInsider adds, used a combination of genetic analyses, reviews of lab notebooks and other documents, and interviews with involved researchers to come to its conclusions.
"It is unlikely that there was accidental contamination by three different ES cells, and it is suspected that the contamination may have occurred artificially," the report says.
The panel, however, did not place blame on any one researcher because it was unable to find conclusive proof that the contamination was done on purpose or who might've done it.