Heart attacks are the leading cause of death in the industrialized world. Interest is growing in the use of stem cells to treat the irreversible damage caused by a heart attack. Recent studies have shown hematopoietic stem cells (HSCs), stem cells in the bone marrow, can form heart cells. HSCs are easy to obtain, avoid the ethical issues associated with embryonic stem cells, and their use in bone marrow transplants is well established. The major challenge facing the use of stem cell therapy to treat heart disease is cell survival after transplantation. Heather Heine is comparing different subpopulations of these cells to determine the optimal type to use for treating the heart, how best to administer the stem cells, and how to improve cell survival in the oxygen-depleted environment created by a heart attack. This research could contribute to more effective therapy for improving cardiac function and survival following a heart attack.