Spatial complexity of cardiac cell culture and spatial-temporal bioelectric activity: granularity and mechanical-electrical feedback.

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The study is aimed at understanding the link between the bioelectrical and biomechanical properties of cultured stem-cell derived cardiomyocytes (SC-CMs) and their role on spontaneous electrical activity. Derived monolayers are complex and heterogeneous set of connected cells. Enriched SC-CMs obtained from stem cells are concentrated cardiomyocytes-like cells with heterogeneous bioelectrical properties leading to a multi-cellular connected mesh of excitable cells when cultured in monolayers. The research program will help better understand the effects of cell population heterogeneity, the role of electrical stimulation and mechanical deformation on bioelectric characteristics and spatial-temporal multicellular self-organization. To achieve this goal, the program has been divided in three parts. 1- Development of an imaging system with feedback process based on spontaneous rhythm of SC-CMs culture. We are developing an approach for culture and monitoring of contractile activity during differentiation of cardiomyocyte-like cells. This "on-chip" culture approach offers a stable and continuous evaluation of engineered stem cells-derived cardiac tissue. The wide range of available frame rates and image resolutions demonstrates the adaptability of our system. Therefore, cell distribution can be evaluated as well as functional characteristics. A feedback process based on the rate and heterogeneity of contraction will be added. An evaluation of the feedback effects on spontaneous activity of different type of electrical stimulation protocol will be studied. 2- Study the spatial-temporal heterogeneity in spontaneous rhythm of derived cardiomyocytes in monolayers. Using our integrated culture-imaging system we aim to study the time-dependent process of SC-CMs monolayer formation and heterogeneity of spontaneous activity. Stem cell differentiation in monolayers is a stochastic process such that how heterogeneous populations are distributed within the monolayer is unknown. To better understand this process, we will also compare, with our mathematical models, the role of heterogeneous cell distribution and dispersion of intrinsic frequencies of autonomous electrical activity on electrical self-organization. 3- Evaluate the effects of mechanical-electrical feedback on the spontaneous activity of SC-CMs monolayers. We have developed a stretching apparatus to study the effects of mechanical deformation on spatial-temporal electrical activity. The acute effects of stretch on SC-CM monolayer spatial-temporal activity remain unknown. Two mechanisms known as clocks (voltage and calcium) could play a central role on spontaneous activity. The importance on spontaneous activity under stretch will be studied using fluorescence mapping. The high level of complexity of SC-CM engineered tissue dynamics needs integration of these innovative approaches and techniques to uncover the multiscale changes occurring and the functional impact on electrical activity.