Abstract 810: Structural and Electrophysiological Maturation of Human iPSC-Derived Atrial Cardiomyocytes to Serve as a Platform to Model Atrial Fibrillation

Abstract

Background: Atrial fibrillation (AF), the most globally common arrhythmia requiring treatment, is associated with significant morbidity and mortality. Although antiarrhythmic drugs (AADs) are most commonly used to treat symptomatic AF, AADs are incompletely and unpredictably effective, and fail to target underlying cellular mechanisms of AF. Previously, pluripotent stem cell derived immature atrial cardiomyocytes (iPSC-aCMs) were shown to recapitulate the structural and electrophysiologic (EP) phenotype of AF-linked mutations. However, there are gaps in structural and EP phenotype between immature and mature iPSC-aCMs to successfully evaluate cellular mechanisms. Objective: The goal is to determine optimal condition(s) to enhance maturity of iPSC-aCMs, to establish iPSC-aCMs as a novel platform to model AF in a dish, elucidate cellular mechanisms and molecular pathogenesis, and identify and assess novel, personalized mechanism based therapies. Methods: Conditions used to enhance iPSC-aCMs maturity are 1) different ECMs to culture iPSC-aCMs, 2) patterned ECM to improve alignment and formation of intercellular gap junctions, and 3) treatment with postnatal factors (T3, IGF-1 and dexamethasone; TID). Maturity was assessed with immunofluorescence and EP measurement with patch-clamping and optical voltage analysis. Results were compared to equivalent parameters in adult atrial cardiomyocytes (aCM) and untreated atrial iPSC-CMs. Results: Fibronectin and laminin were ECMs found suitable for long time culture of iPSC-aCMs. Structural maturity (α-actinin and cardiac troponin T) and EP maturity (resting membrane potential [83 ± 3%], APD 90 [67 ± 2.5%], and conduction velocity [59.6 ±3%]) with patterned ECM and TID treatment were significantly improved compared to untreated iPSC-aCMs, and closer to those of adult aCMs. Conclusion: Structural and EP maturity of iPSC-aCMs are significantly enhanced by precise microenvironmental engineering of in-vivo relevant cell-cell, cell-ECM, and cell-soluble factor interactions. Thus, our findings will provide a platform to investigate cellular mechanisms of AF.