Perfusion Improves Tissue Architecture of Engineered Cardiac Muscle

TLDR

Cardiac muscle with sufficient thickness, uniform architecture, and function could broaden therapeutic options for patients with congenital or acquired cardiac defects. The study hypothesized that direct perfusion of cultured constructs would reduce diffusional distances and improve oxygen, pH, nutrient, and metabolite control, thereby increasing the thickness and spatial uniformity of engineered cardiac muscle. The authors cultured 9.5‑mm‑diameter, 2‑mm‑thick neonatal rat cardiac myocyte constructs on polyglycolic acid scaffolds either with direct medium perfusion or in control spinner flasks. Perfusion produced a more uniform cell distribution, enhanced cardiac‑specific marker expression, and yielded constructs with a thicker, more homogeneous tissue layer—demonstrating that medium perfusion can better mimic native cardiac transport conditions and enable clinically useful engineered muscle thicknesses.

Abstract

Cardiac muscle with a certain threshold thickness, uniformity of tissue architecture, and functionality would expand the therapeutic options currently available to patients with congenital or acquired cardiac defects. Cardiac constructs cultured in well-mixed medium had an approximately 100-microm-thick peripheral tissue-like region around a relatively cell-free interior, a structure consistent with the presence of concentration gradients within the tissue. We hypothesized that direct perfusion of cultured constructs can reduce diffusional distances for mass transport, improve control of oxygen, pH, nutrients and metabolites in the cell microenvironment, and thereby increase the thickness and spatial uniformity of engineered cardiac muscle. To test this hypothesis, constructs (9.5-mm-diameter, 2-mm-thick discs) based on neonatal rat cardiac myocytes and fibrous polyglycolic acid scaffolds were cultured either directly perfused with medium or in control spinner flasks. Perfusion improved the spatial uniformity of cell distribution and enhanced the expression of cardiac-specific markers, presumably due to the improved control of local microenvironmental conditions within the forming tissue. Medium perfusion could thus be utilized to better mimic the transport conditions within native cardiac muscle and enable in vitro engineering of cardiac constructs with clinically useful thicknesses.