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.