Tissue engineering of functional cardiac muscle: molecular, structural, and electrophysiological studies

TLDR

The study aimed to correlate the molecular and structural properties of engineered cardiac muscle with its electrophysiological function using neonatal rat myocytes, 3‑D polymeric scaffolds, and bioreactors. Engineered cardiac muscle was produced by seeding neonatal rat myocytes onto laminin‑coated 3‑D polymeric scaffolds and culturing them in rotating bioreactors with low‑serum medium. After one week, the tissue displayed a 120–160 µm peripheral region of electrically coupled myocytes that supported continuous impulse propagation over 5 mm, and its conduction velocity, connexin43 distribution, cellularity, signal amplitude, capture rate, and excitation threshold matched native tissue and exceeded prior studies.

Abstract

The primary aim of this study was to relate molecular and structural properties of in vitro reconstructed cardiac muscle with its electrophysiological function using an in vitro model system based on neonatal rat cardiac myocytes, three-dimensional polymeric scaffolds, and bioreactors. After 1 wk of cultivation, we found that engineered cardiac muscle contained a 120- to 160-μm-thick peripheral region with cardiac myocytes that were electrically connected through gap junctions and sustained macroscopically continuous impulse propagation over a distance of 5 mm. Molecular, structural, and electrophysiological properties were found to be interrelated and depended on specific model system parameters such as the tissue culture substrate, bioreactor, and culture medium. Native tissue and the best experimental group (engineered cardiac muscle cultivated using laminin-coated scaffolds, rotating bioreactors, and low-serum medium) were comparable with respect to the conduction velocity of propagated electrical impulses and spatial distribution of connexin43. Furthermore, the structural and electrophysiological properties of the engineered cardiac muscle, such as cellularity, conduction velocity, maximum signal amplitude, capture rate, and excitation threshold, were significantly improved compared with our previous studies.