The leg bone's connected to the…cerebellum?

In a result that bodes well for medical applications of stem cells, Priller et al. report on page 733 that bonemarrow-derived stem cells can differentiate into apparently normal Purkinje neurons in an adult mouse brain. Although previous work demonstrated that bone marrow transferred into an irradiated mouse could give rise to cells expressing neuronal markers, the authors are the first to identify donor-derived neurons that appear to be morphologically normal and functional, and to determine that the donor-derived cells survive as the mouse ages.

The authors transferred the green fluorescent protein (GFP) gene into donor bone marrow cells, and then identified GFP- expressing cells in the brains of mice that received the transplanted bone marrow. Donor-derived Purkinje cells were not seen four months after transplantation, but had appeared by 12 months posttransplantation and...