Compositions comprising stem cells delivered into infarcted myocardium by endocardial injection, engraft and differentiate into myocytes, endothelial cells, and vascular smooth muscle, and do so without the requirement for survival enhancing modification. These cells engraft whether injected acutely (days) or late (months) after myocardial infarction, and the efficiency of engraftment correlates with the functional recovery of the heart. The stem cells also recruit endogenous cardiac precursor cells, reconstitute myocardial stem cell niches, and enhance endogenous cell differentiation into myocytes.
