Endothelial Cardiac Cell Therapy

Cell-based therapies represent a promising strategy for regeneration of myocardial tissue, and it is clear that impaired contractile function can be improved even when transplanted cells do not persist in the myocardium.1 Many cell types and mechanisms have been proposed for the benefits of cardiac cell therapy, including the formation of new myocytes, endothelial cells, and vascular smooth muscle cells, as well as through paracrine effects.2 In part because we do not yet understand these mechanisms, the ideal cell type and delivery approach for cardiac cell therapy has not yet emerged.Article, see p 882Endothelial progenitor cells (EPCs) are a subset of hematopoietic cells found in the bone marrow that have the potential to differentiate into endothelial cells and have a role in promoting angiogenesis and prosurvival signals to cardiomyocytes.3,4 EPCs are readily isolated from the blood and the bone marrow, and clinical studies suggest that cell-based therapy with EPCs can improve myocardial function.5 A subset of mesenchymal stem cells can differentiate into cardiomyocytes under specific conditions in vitro.6,7 Bone marrow–derived cell therapy can stimulate endogenous cardiomyocyte progenitors and promotes cardiac repair.8 Methods to limit teratoma formation include genetic selection of differentiated embryonic stem (ES) cells, or differentiation of ES cells in vitro into cardiomyocytes or endothelial cells before injection.9,10 An inherent difficulty in controlling the growth and differentiation of ES cells and other pluripotent stem cells is that the timing with which …