Cell sources for cardiac regeneration--which cells and why.

Realizing the promise of therapeutic cardiac regeneration requires the targeting of accessible cell sources to promote neomyogenesis for the injured heart. After initial trials with cardiac myocytes and skeletal muscle progenitor cells (myoblasts), the rapid advances of stem cell technology have established the feasibility of endogenous stem cells to serve as donor cells for cellular cardiomyoplasty. In particular, bone marrow-derived stem cells have a great potential for clinical application due to their extracardiac locale and capacity to give rise to functional cardiac myocytes. The recent identification of resident cardiac stem cells also offers the opportunity to regenerate the infarcted myocardium, using the cells from the heart for ex vivo expansion or as targets for in vivo induction. To this end, future advances in cellular cardiomyoplasty may likely be based on therapies stimulating the trophic/cellular interactions that direct exogenous/endogenous stem cell-mediated cardiac regeneration.