Abstract 153: Creation of Cell Sheet-Based Bioengineered Cardiac Tissue Using Pluripotent Stem Cell-Derived Cells

Recent evidences have suggested that current cardiac cell therapy contributes to the improved cardiac function through mainly the paracrine effects. Thereby the bioengineered functional heart tissue is expected to function for repairing the broad injured heart. We have developed the cell sheet-based bioengineered vascularized cardiac tissue, however the system to collect the enough amount of cells from ES/iPS cells and the function of ES-derived cardiac tissue remain elusive. Recently we have established the cultivation system with the suitable conditions for expansion and cardiac differentiation of mouse ES cells and human iPS cells via embryoid body formation using three-dimensional bioreactor with the continuous perfusion system. For the cardiac differentiation experiments, we used several mouse ES cells that express EGFP or neomycin resistant gene under the control of αMHC promoter. At 10 days of differentiation, mouse ES cells increased up to 300 times (6.0×10 6 cells/mL). After the further 8 days of cultivation with the purification step, we collected around 5.0×10 8 cells in the 1L bioreactor culture and 99% of cells were positive for myosin heavy chain. The co-culture of ES-derived cardiomyocytes with the appropriate number of primary cultured fibroblasts on the temperature-responsive culture dishes enabled to form the cardiac cell sheets. Furthermore, when ES-derived cardiomyocytes were co-cultured with ES-derived endothelial cells, robust endothelial cell network was observed in the cardiac cell sheets. Mouse ES- or human iPS-derived cardiomyocytes in cell sheets beat spontaneously and synchronously and connexin43 was expressed at the edge of the adjacent cardiomyocytes. Furthermore the action potential propagation was observed between ES/iPS-derived cardiac cell sheets. These findings suggest that pluripotent stem cell-derived cardiomyocytes and endothelial cells might be useful for creating cell-sheet-based functional cardiac tissue and the layered stem cell-derived cardiac tissue might promote not only the cardiac regenerative medicine but also the understanding the molecular mechanisms of heart diseases.