The authors of a controversial paper on stem cells publish a correction of their work in this week’s issue of Nature (447, 880-881; 2007) but state in it that the errors do not affect the conclusions of the article. A News story also in this week’s issue (Nature 447, 763; 2007) describes how the paper in question, published in 2002, claimed to find evidence for so-called ‘multipotent adult progenitor cells’, or MAPCs, in mouse bone marrow (Y. Jiang et al. Nature 418, 41–49; 2002). The work was led by Catherine Verfaillie, now director of the Stem Cell Institute at the Catholic University of Leuven.

From the News story: The paper challenged the prevailing idea that only stem cells derived from embryos were highly flexible. Some of its results have been reproduced by other labs, but no one has been able to replicate the work independently in its entirety. “I believe that despite the hype over the mistake, we and Nature made the conclusion that the final findings of the paper still stand,” says Verfaillie.

This February, an investigation convened by the University of Minnesota — Verfaillie’s former institution — found that her group had used incorrect procedures in the Nature paper, and that some of the data contained in it might be flawed. The investigation was a response to questions from a reporter from the magazine New Scientist, who pointed out that the figure from the Nature paper that has now been corrected was partly reproduced with different labels in another paper in another journal, Experimental Hematology (Y. Jiang et al. Exp. Hematol. 30, 896–904; 2002).

In response to the investigation, Nature convened a peer-review panel to analyse the data from the 2002 paper. According to Nature, the experts concluded that although the figure data were flawed, the paper’s conclusions are still valid. No allegations of fraud or misconduct have been levelled at Verfaillie or anyone from her group. Verfaillie says her group cannot explain how the errors in the Nature paper occurred: “Why this happened, we have not been able to determine,” she says.