Adult cardiac stem cells are multipotent and support myocardial regeneration

The notion of the adult heart as terminally differenti- ated organ without self-renewal potential has been undermined by the existence of a subpopulation of replicating myocytes in normal and pathological states. The origin and significance of these cells has remained obscure for lack of a proper biological con- text. We report the existence of Lin c-kitPOS cells with the properties of cardiac stem cells. They are self- renewing, clonogenic, and multipotent, giving rise to myocytes, smooth muscle, and endothelial cells. When injected into an ischemic heart, these cells or their clonal progeny reconstitute well-differentiated myo- cardium, formed by blood-carrying new vessels and myocytes with the characteristics of young cells, en- compassing 70% of the ventricle. Thus, the adult heart, like the brain, is mainly composed of terminally differentiated cells, but is not a terminally differenti- ated organ because it contains stem cells supporting its regeneration. The existence of these cells opens new opportunities for myocardial repair