Biocompatibility evaluation of electrically conductive nanofibrous scaffolds for cardiac tissue engineering

Myocardial tissue engineering offers a novel technology to improve or regenerate cardiac functions using a combination of cells, biomaterials and engineering strategies. Inspired by low-resistance pathways for electrical signal propagation in the native heart tissue, electrically conductive nanofibrous scaffolds composed of melanin, poly(l-lactide-co-ε-caprolactone) and gelatin were fabricated to provide electrophysiological cues to cardiac myocytes and mimic the native myocardial environment. Our results show that by increasing the concentration of melanin to 40% within the composite, the fiber diameters reduced to 153 ± 30 nm, modulus decreased to 7.1 ± 0.6 MPa, and conductance increased to 259.51 ± 187.60 μS cm^-1. Results of cell proliferation and immunostaining analysis of human cardiac myocytes demonstrated that the conductive nanofibers containing 10% melanin promote cell interaction with expression of cardiac-specific proteins compared to other scaffolds. Electrical stimulation through the scaffolds showed enhanced cell proliferation and the expression of connexin-43, signifying the potential of using melanin containing nanofibers as a suitable cardiac patch for the regeneration of infarct myocardium.