Bone marrow cells regenerate infarcted myocardium

Myocardial infarction leads to loss of tissue and impairment of cardiac per formance. The remaining myocytes are unable to reconstitute the necrotic ti ssue, and the post-infarcted heart deteriorates with time(1). Injury to a t arget organ is sensed by distant stem cells, which migrate to the site of d amage and undergo alternate stem cell differentiation(2-5); these events pr omote structural and functional repair(6-8). This high degree of stem cell plasticity prompted us to test whether dead myocardium could be restored by transplanting bone marrow cells in infarcted mice. We sorted lineage-negat ive (Lin(-)) bone marrow cells from transgenic mice expressing enhanced gre en fluorescent protein(9) by fluorescence-activated cell sorting on the bas is of c-kit expression(10). Shortly after coronary ligation, Lin(-) c-kit(P OS) cells were injected in the contracting wall bordering the infarct. Here we report that newly formed myocardium occupied 68% of the infarcted porti on of the ventricle 9 days after transplanting the bone marrow cells. The d eveloping tissue comprised proliferating myocytes and vascular structures. Our studies indicate that locally delivered bone marrow cells can generate de novo myocardium, ameliorating the outcome of coronary artery disease.