Stem cells in the heart: what's the buzz all about?--Part 1: preclinical considerations.

New approaches for cardiac repair have been enabled by the discovery that the heart contains its own reservoir of stem cells. These cells are positive for various stem/progenitor cell markers, are self-renewing, and exhibit multilineage differentiation potential. Recently we developed a method for ex vivo expansion of cardiac-derived stem cells from human myocardial biopsies with a view to subsequent autologous transplantation for myocardial regeneration. Here we review the state of the cardiac stem cell field and our own work on cardiosphere-derived stem cells from human hearts. The first of this two-part review outlines emerging preclinical data on the application of cardiac stem cells. Part 2 continues with a discussion of other stem cell sources with clinical potential, a summary of the critical issues surrounding stem cell therapy (with an emphasis on the crucial issue of how cell transplantation may influence arrhythmias), our perception of clinical stem cell trials to date, and the issues facing the clinical application of cardiac stem cells.