(From ScienceDaily). However it is that adult stem cell therapies - such as for heart damage - produce results, it does not seem to be the way scientists were hoping for: "Previous studies suggested that stem cells from bone marrow could be induced to become cardiac muscle, replacing damaged tissue and potentially restoring heart function. This series of more-rigorous experiments, however, found that the transplanted cells are unable to take the crucial final steps. They do not produce a muscle protein called sarcoglycan, which is necessary for normal heart and skeletal muscle function. ... It's clear that the transplanted cells aren't growing, as we once hoped, into heart cells, but they may stimulate the growth of new blood vessels into the damaged regions or they may secrete growth factors that promote recovery."