Growth and differentiation of human embryonic stem cells for cardiac cell replacement therapy

Due to the limited proliferation capacity of cardiac cells, cell replacement therapy has been proposed to restore cardiac function in patients suffering from ischemic heart disease and congestive heart failure. However, this approach is challenged by an insufficient supply of appropriate cells. Because of their apparent indefinite replicative capacity and their cardiac differentiation potential, human embryonic stem cells (hESCs) are potential candidates as sources of cells for cell replacement therapy. Significant progress has been made in improving culture conditions of undifferentiated hESCs, and using various methods, several laboratories have reported the generation of contracting cardiomyocytes from hESCs in vitro. Application of these cardiomyocytes to the clinic, however, still requires substantial experimentation to show that 1) they are functional in vitro; 2) they are efficacious in animal models of cardiac injury and disease; 3) they are safe and effective in human conditions, and 4) a sufficient amount of cardiomyocytes with expected characteristics can be generated in a reproducible manner. Here we review and discuss current findings on growth and differentiation of hESCs, and on characterization, enrichment and transplantation of hESC-derived cardiomyocytes.