[Stem cell therapy for myocardial regeneration: mechanisms and current clinical applications]

Ischemic heart disease is a major public health problem in the industrialized and developing world. Despite advances in myocardial reperfusion strategies and novel pharmacological approaches, ther apies directed towards the deleterious consequences of acute and chronic myocardial ischemic damage remain limited. In recent years the biological dogma of the heart as a "postmitotic organ" has been challenged. Myocyte replication and myocardial regeneration have been documented in the human heart after myocardial infarction and in chronic ischemic heart failure. In addition, experimental animal studies and clinical trials suggest that the transfer of stem and progenitor cells into the myocardium has a favorable impact on tissue perfusion and contractile performance. Neovascularization and myocyte formation have been described. Differentiation of administered stem cells, cell fusion and release of paracrine signals by injected stem cells are currently discussed as underlying mechanisms. Recently, the mobilization of endogenous cardiac stem cells is debated as a potential target of cardiac repair. This intriguing new knowledge generated by basic and clinical scientists will lay the foundation for novel therapeutic strategies in the near future and change clinical practice in cardiology. In this commentary, we briefly review the characterization of the variety of stem cell populations used for cardiac repair, discuss the potential mechanisms of cardiac regenerative therapy, and evaluate the current clinical applications of this innovative approach to treat ischemic heart disease.