Stem Cell Double Play

A matched set of articles published online by the British science journal Nature last week seemed calculated to provide succor to both sides in the simmering stem-cell debate. In one study, University of Minnesota researchers isolated bone-marrow cells from adult mice, grew them in dishes and injected them into mouse embryos, where they developed into nerve, liver and other types of cells. In the other study, scientists from the National Institutes of Health did similar work with stem cells from mouse embryos, which developed into brain cells that produce dopamine and could be used to treat Parkinson's disease.

Proponents of human therapeutic cloning hailed the NIH study as proof that scientists need to work with stem cells taken from embryos. Foes cited the Minnesota work as proof that the same results can be achieved without embryos.

Nature says it wasn't trying to influence the stem-cell debate and that it often pairs related articles. (These two will be printed in the July 4 issue.) The editors also insist that the timing--appearing on the Web at the moment the U.S. Senate is stalled on two competing cloning bills--was simply to avoid being scooped by its rival, Science.

--By Jeffrey Kluger