The far-reaching effects of a heart attack explain why using patients' own bone-marrow cells to repair cardiac damage has yielded only modest results in clinical trials.

Matthew Springer and his colleagues at the University of California, San Francisco, report that a heart attack changes the composition of the bone marrow cells. The event triggers inflammation throughout the body, shifting the composition of the cells in the bone marrow and making it more inflammatory. When mice that had suffered heart damage were treated with bone-marrow cells from other heart-damaged mice, their cardiac function improved less than mice treated with cells from healthy animals. However, if the donor mice received an anti-inflammatory drug after sustaining heart damage, the cells regained their full therapeutic potential.

Sci. Transl. Med. 3, 100ra90 (2011)