(25f) Regeneration of Electrophysiologically Functional Atrial Cardiac Tissues on Anisotropic Fibrillar Fibronectin Matrix

Recapitulating the functional architecture of myocardium is one of the main challenges in cardiac tissue regeneration and disease modeling. Current tissue engineering methods primarily rely on synthetic polymers to fabricate nanofibers and micropatterned templates to mimic the direction-dependent (anisotropic) cardiac conduction. However, these synthetic substrates lack the functional advantage rendered by native extracellular matrix proteins. Through a fluid shear stress-induced protein fibrillogenesis, we developed a highly anisotropic, fibrillar extracellular matrices composed of fibronectin (FN) as a novel contractile platform to assess the anisotropic function of iPSC-derived cardiac tissues. Using this engineered biomimetic FN matrix, we test the hypothesis that the topographical alignment of cardiomyocytes is essential for the proper hierarchical organization and the development of cardiac contractile and electrophysiological functions. Human pluripotent stem cell-derived atrial-like cardiomyocytes (hPSC-ACMs) cultured on anisotropic FN matrices adapt the physiological orientation and display significant sarcomeric organization to form in-vivo-like syncytium. Electrophysiological readouts of intracellular calcium transient reveal that the anisotropic FN matrices promote better intercellular calcium handling and yield greater maturity in the cardiac tissues when compared to the monolayer control of cardiomyocytes. Notably, the cardiac tissues regenerated on the anisotropic FN matrix (CTAFs) exhibited higher average conduction velocities and significant amplitudes of calcium transient, indicating greater intercellular connectivity of cardiomyocytes through gap junctions and an increase in calcium handling functionalities. The regulated anisotropic alignment of fibrillar fibronectin matrix achieved in this work unlocks a new possibility of ex-vivo cardiac tissue transplants and novel drug discovery platform with anisotropic functionality in regenerative medicine and disease modeling.