Abstract 18901: Endothelium Based Feeder Improves Capacity of Human Embryonic Stem Cells Derived Cardiomyocytes

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Introduction: The regenerative ability of the heart is very low, making patients with myocardial damage potential candidates for cell-based regenerative therapy. Pluripotent human embryonic stem cells (hESC) are a promising source of cardiomyocytes (CMs). While the quantity of CMs obtained is no longer a limitation in current differentiation protocols, their functionality remains to be improved. Indeed contracting areas in cell cultures are still heterogeneous and non-consistent Hypothesis: Endothelial cells (ECs) and CMs are derived from a common precursor. Moreover, endothelial secreted and contact dependent factors play a role at different phases of cardiac development and repair. We hypothesized that creating a mixture of cell types that more closely resembles heart tissue - i.e. containing both ECs and CMs - will lead to improved maturation and functionality Methods: We co-cultured NKX2-5-GFP reporter hESC line and an autonomous Akt-activated ECs and induced differentiation of NKX2-5GFP hESC into CMs We assessed functionality by evaluating beating and coordination between different CMs clusters. Results: Around 94% ± 6 of the NKX2-5GFP+ cells were beating when hESCs embryonic body (EBs) were plated on E4+ECs comparing to 34% ± 12.9 for controls. The spatial organization of beating areas in co-cultures was different. In 7 different experiments clustered in two populations, the average BPM of CMs in co-culture was faster and closer to a physiologic heart rate compare to controls (49.6 ± 13.77; n=13 vs 24.76 ±9.36; n=8 for controls; p<0.05). Our protocol increased and accelerated the differentiation of CMs. More importantly CMs formed under these conditions displayed a higher rate of contractility with synchronized beating relying on an endothelial network. Conclusions: We have been able to build a culture platform in vitro capturing partially complexity of cardiac tissue. Such strategy resulted in the obtaining of more synchronized interconnected CMs nodes displaying faster beating. Our data showed that co-culture of differentiating hESCs with ECs increased functionality of the CMs, suggesting that an endothelial based feeder could promote the in vitro functionalization of clinically relevant cell type.