Comments about possible use of human embryonic stem cell-derived cardiomyocytes to direct autologous adult stem cells into the cardiomyogenic lineage.

Several studies have shown that cell-transplantation therapy following myocardial infarction has some efficacy in aiding myocardial repair and subsequent recovery of heart function. Large-scale production of human embryonic stem cell-derived cardiomyocytes can potentially provide an abundant supply of donor cells for myocardial transplantation. There are, however, immunological barriers to their use in human clinical therapy.A novel approach would be to look at utilizing human embryonic stem cell-derived cardiomyocytes to reprogram autologous adult stem cells to express cardiomyogenic function, instead of using these directly for transplantation. This could be achieved through a number of novel techniques. Enucleated cytoplasts generated from human embryonic stem cell-derived cardiomyocytes could be fused with autologous adult stem cells to generate cytoplasmic hybrids or cybrids. Adult stem cells could also be temporarily permeabilized and exposed to cytoplasmic extracts derived from these cardiomyocytes. Alternatively, intact cells or enucleated cytoplasts from human embryonic stem cell-derived cardiomyocytes could be co-cultured with adult stem cells in vitro, to provide the cellular contacts and electrical coupling that might enable some degree of trans-differentiation to take place. This review would therefore examine the potential advantages and disadvantages of such a novel approach, in comparison to other more conventional techniques such as the use of exogenous cytokines/growth factors or the use of genetic modulation.