Abstract 556: Cardiomyocytes from Human Embryonic Stem Cells Using an Efficient Directed Differentiation Method: In Vitro Characterization and Transplantation
Human embryonic stem cells represent a potential source of specialized cells for regenerative medicine, particularly important in the repair of non-regenerative tissues such as the heart. Traditional methods for generating cardiomyocytes from hES cells have several drawbacks, including the requirement for embryoid body formation and high concentrations of calf serum or use of nonhuman cells in co-culture. We have identified a method that is performed in serum-free medium using a simple sequential combination of defined growth factors and that does not require generation of embryoid bodies or co-culture with other cell types. The cells that arise by this method express the appropriate cardiomyocyte transcription factors and structural proteins. Kinetic studies reveal the sequential activation of mesodermal and precardiac mesodermal genes, followed by the rapid acquisition of organized sarcomeric proteins and spontaneous contractions. This method generates cardiomyocytes at an efficiency of up to 80% of the total cells without further purification; additional purification using density gradients have resulted in high yields with purities greater than 95%. The high efficiency of this method (large numbers of beating cells are evident within 8 –12 days after the addition of growth factors) enables the generation of large numbers of cells for in vitro studies as well as transplantation. We describe here the histological and electrophysiological properties of the cardiomyocytes generated by this directed differentiation method and show preliminary transplantation results.