Cardiac regeneration: repopulating the heart

Many forms of pediatric and adult heart disease result from a deficiency in cardiomyocyte number. Through repopulation of the heart with new cardiomyocytes (that is, induction of regenerative cardiac growth), cardiac disease potentially can be reversed, provided that the newly formed myocytes structurally and functionally integrate in the preexisting myocardium. A number of approaches have been utilized to effect regenerative growth of the myocardium in experimental animals. These include interventions aimed at enhancing the ability of cardiomyocytes to proliferate in response to cardiac injury, as well as transplantation of cardiomyocytes or myogenic stem cells into diseased hearts. Here we review efforts to induce myocardial regeneration. We also provide a critical review of techniques currently used to assess cardiac regeneration and functional integration of de novo cardiomyocytes.