Three stem cell scientists have retracted a paper they published early this year in Nature. Details are sketchy, but in the retraction, released today, they say that a "re-examination" of the paper "raised serious concerns."
In a series of experiments, the group joined the blood circulation of old and young mice, a method that's been used for decades in different kinds of studies, to test whether animals with a certain feature (youth, in this case) can impart it to others that don't have it. The authors, led by Amy Wagers at the Joslin Diabetes Center and Harvard Medical School in Boston, reported that the old mice did develop features of younger ones, in particular in the balance of different types of bone marrow cells. They traced this change to signals from certain bone-forming cells affecting blood stem cells from the young animals. A Harvard publication gives a nice summary of the work here.
The retraction specifies that three of the four authors have specifically lost confidence in the paper's findings about the role of these bone cells. They say that the first author, postdoc Shane Mayack, did not sign on to the retraction and maintains the results are still valid. The blog Retraction Watch has some more details.