Cardiomyocyte coculture on layered fibrous scaffolds assembled from micropatterned electrospun mats

Challenges remain in engineering cardiac tissues with functional and morphological properties similar to those of native myocardium. In the current study, micropatterned fibrous mats are obtained by deposition of electrospun fibers on lithographic collectors to reproduce the anisotropic structure of myocardium, and carbon nanotubes are included in fibers to provide conductivities at the same level of cardiac muscles. The patterned mats are assembled layer-by-layer into patterned scaffolds for coculture of primary cardiomyocytes (CMs) with cardiac fibroblasts (CFs) and endothelial cells (ECs). CMs are organized along the fibers with clear cardiac strips of sarcomeric α-actinin and belt-like connexin-43, showing strong cellular extraction forces and intercellular communications. Compared with square and rectangle patterns, honeycomb (Hc)-patterned scaffolds shows higher ultimate tensile strength and strain to failure. The finite element analysis indicates no apparent stress concentration under stress application in the two orthogonal directions. The Hc-patterned coculture demonstrates significantly higher CM viabilities, deeper penetrations of cells into scaffolds, stronger expression of troponin I, connexin-43 and sarcomeric α-actinin by CMs and more abundant formations of capillary-like networks by ECs than other scaffolds. CMs on Hc-patterned scaffolds display spontaneous beating rates at 101±12times/min after coculture for 5days and remain synchronously beating at 94±8times/min after 15days, which is close to those of adult and neonatal rats. The layered and patterned coculture strategy achieves the spatial arrangement of multiple types of cells and vascularization potential, providing a biomimetic strategy for engineering functional cardiac patches in vitro.