(567aj) Expansion and Cardiac Differentiation of Embryonic Stem Cells (ESCs) in 3-Dimensional (3-D) Culture Systems

Heart disease is one of top causes of death in the US and the world. Many heart diseases are related to the progressive loss of functional cardiomyocytes. Because cardiomyocytes cannot proliferate after birth, cell transplantation therapy has emerged as a potential therapeutic approach for replacing injured myocardial tissue and repair cardiac function. Embryonic stem cells (ESCs) are pluripotent and can generate all three germ layers. Therefore, differentiation of embryonic stem cells to cardiomyocytes has become a promising method for heart repair and regeneration. In this study, two 3-D bioreactor culture systems using polyethylene terephthalate (PET) fibrous matrices as cell supports were developed. PET fibrous matrices provided large surface areas and an in vivo-like 3-D environment so that facilitated high density cell growth and promoted ESC expansion and differentiation. Murine ESCs were inoculated into small patches of PET matrices in a 125-ml bioreactor as a suspension culture and into a fibrous bed bioreactor (FBB) packed with PET matrices, respectively. These two culture systems were kept in an expansion medium for 4 days, replaced with embryonic bodies (EB) formation medium for 4 days and then the differentiation medium to induce cardiac differentiation for 14 days. In general, both culture systems supported integrated ESCs expansion and cardiac differentiation in 3-D PET metrices. Cells were greatly expanded with a significant fraction of cells showing cardiogenesis as confirmed using immunostaining, flow cytometry analysis and reverse transcriptase polymerase chain reaction in both cultures. These simplified, scalable, 3-D bioreactor culture systems exhibit great potentials in mass producing ESC derivative cells for clinical applications.