Cardiac muscle tissue engineering: toward an in vitro model for electrophysiological studies

TLDR

The study aimed to create a 3‑D in‑vitro cardiac muscle model for electrophysiological investigations. Neonatal rat ventricular cells with varying myocyte fractions were cultured on polymeric scaffolds in bioreactors to produce regular or enriched 3‑D cardiac muscle constructs. The constructs developed a peripheral, multilayered cardiac myocyte region that matched native cell size and metabolic activity, displayed homogeneous electrical conduction with continuous impulse propagation over centimeter scales, and showed that enriched constructs had superior electrophysiological properties compared to regular ones but still fell short of native ventricles.

Abstract

The objective of this study was to establish a three-dimensional (3-D) in vitro model system of cardiac muscle for electrophysiological studies. Primary neonatal rat ventricular cells containing lower or higher fractions of cardiac myocytes were cultured on polymeric scaffolds in bioreactors to form regular or enriched cardiac muscle constructs, respectively. After 1 wk, all constructs contained a peripheral tissue-like region (50–70 μm thick) in which differentiated cardiac myocytes were organized in multiple layers in a 3-D configuration. Indexes of cell size (protein/DNA) and metabolic activity (tetrazolium conversion/DNA) were similar for constructs and neonatal rat ventricles. Electrophysiological studies conducted using a linear array of extracellular electrodes showed that the peripheral region of constructs exhibited relatively homogeneous electrical properties and sustained macroscopically continuous impulse propagation on a centimeter-size scale. Electrophysiological properties of enriched constructs were superior to those of regular constructs but inferior to those of native ventricles. These results demonstrate that 3-D cardiac muscle constructs can be engineered with cardiac-specific structural and electrophysiological properties and used for in vitro impulse propagation studies.