Figure 1: Ischemic injury to the myocardium causes the release of chemokines (G-CSF, SCF, and SDF-1), which mobilize quiescent stem cells from the bone marrow to peripheral circulation. Once in circulation, mobilized stem cells migrate along the chemotactic gradient towards its source at the site of ischemic tissue damage. Once in the damaged tissues, stem cells may mediate repair through transdifferentiation, cell fusion or paracrine support. Magnified on the left is a cardiac stem cell, showing the chemokine receptor/ ligand interaction (CXCR-4/SDF-1) and other surface markers that may signify pluripotency (CD34, c-kit).