Controversial stem cell paper retracted as cells 'never existed'

The lead author of a controversial study describing a new type of stem cell - stimulus-triggered acquisition pluripotency (STAP) cells - has agreed to retract two research papers published in the journal Nature in January 2014 (reported in BioNews 740).

Dr Haruko Obokata, of the RIKEN Institute in Japan, is said to have agreed to retract the papers after new evidence emerged about the authenticity STAP cells, according to the Japan Daily Press.

A new genetic test analysis of the STAP stem cell lines found that the cells were derived from different strains of mice than stated in the research publications, suggesting contamination. An independent investigation by researchers at RIKEN and Yamanashi University found that the STAP stem cell lines were derived from a combination of B6 and CD1 mouse strains, rather than the F1 mouse strain as described in the original study.

In a press interview, Dr Takaho Endo from RIKEN, who was involved in the investigation, said: 'it is quite unlikely that this happens as a result of an accident or mistake'.

Dr Obokata was found guilty of research misconduct in May 2014 in relation to the two STAP papers published in Nature (reported in BioNews 749). The findings first came under investigation by RIKEN after bloggers questioned whether some of the images presented were duplicated or manipulated (reported in BioNews 743). The institute concluded that Dr Obokata had fabricated some of the images presented in the research papers, duplicated some images and reused images from her doctoral thesis in a way that was deliberately misleading.

Dr Obokata apologised and had previously stood by the research and STAP cells, but has now agreed to retract both papers. All study co-authors must agree before Nature will consider a retraction. Senior author Professor Charles Vacanti, from Harvard Medical School and Brigham and Women's Hospital, is now said to support the retraction, having initially defended the research papers, reports Nature News.

The new genetic analysis findings call into question the existence of STAP cells. The original research concluded that exposure of mature mouse blood cells to stress such as acid or physical pressure results in cell reprogramming, generating pluripotency cells with characteristics similar to embryonic stem cells. To date, no other researchers have been able to replicate the findings of Dr Obokato and her team.