The promotion of HL-1 cardiomyocyte beating using anisotropic collagen-GAG scaffolds

Biomaterials for myocardial tissue engineering must balance structural, mechanical and bioactivity concerns. This work describes the interaction between HL-1 cardiomyocytes and a series of geometrically anisotropic collagen-GAG (CG) scaffolds with aligned tracks of ellipsoidal pores designed to mimic elements of the native geometric anisotropy of cardiac tissue. Here we report the role scaffold geometric anisotropy and pore size plays in directing cardiomyocyte bioactivity. Notably, HL-1 cardiomyocytes showed good proliferation and metabolic activity in all variants out to 14 days in culture. Critically, HL-1s exhibited significantly elevated 3D alignment and earlier spontaneous beating within anisotropic CG scaffolds relative to isotropic scaffold controls. This spontaneous beating occurred at significantly higher instances for larger pore size anisotropic variants. Gene expression and immunohistochemical analyses for key cardiac marker (α-myosin heavy chain, connexin-43) suggest that the isotropic and anisotropic scaffolds support expression of key transcriptomic markers of cardiomyocyte phenotype as well as the formation of gap junctions and elongated, aligned cell morphologies. Collectively, these results suggest that a geometrically anisotropic scaffold with sufficiently large pore size (>150 μm) provides a suitable microenvironment to induce cardiomyocyte alignment, beating, and bioactivity for cardiac tissue engineering applications.