Abstract
There is accumulating evidence that cell-based therapy holds promise to treat diseases characterized by destruction or dysfunction of cardiac myocytes and the gross structure of the heart. The greatest challenge in the field is the characterization of cell types that when adoptively transferred to a recipient heart they are characterized by engraftment and cellular repopulation, which remains to be decisively achieved. Ongoing experiments and clinical trials, however, support the use of cell-based therapy to stimulate endogenous repair mechanisms, thereby achieving reverse remodeling of injured hearts. The most important new concept regarding cardiac repair and homeostasis emerges from data showing myocyte turnover in the postmitotic heart, a phenomenon occurring at a rate of 1%–2%, but declining with age. Accumulating studies shows that the rate can be augmented through a variety of stimuli and, therefore, represents a potential therapeutic target. Tissue repair may occur through paracrine signaling mechanisms that include signals transduced via the molecular cargo of extracellular vesicles. The actual remuscularization of the heart resulting from cellular engraftment and differentiation continues to be experimentally explored.