Medical Rounds

ADULT BEHAVIOR: Just how versatile are adult stem cells? As scientists around the world explore this question, pharmacology professor Helen Blau and graduate student Mark LaBarge have demonstrated that tissue damage may trigger adult stem cells’ transformation into other cell types. The researchers injected mice with whole bone-marrow cells engineered to make a green fluorescent protein. In mice whose bone marrow had been destroyed through irradiation, the green fluorescent marrow generated muscle-specific “satellite” stem cells, but it did not do so in mice without bone-marrow damage. A subgroup of irradiated mice that then sustained muscle damage manufactured replacement muscle fibers that contained the green protein. Blau cautions that the satellite and muscle cells may not have originated from a stem cell, but from a different bone-marrow cell.