Microstructured Cocultures of Cardiac Myocytes and Fibroblasts: A Two-DimensionalIn VitroModel of Cardiac Tissue

Abstract

Cardiac myocytes and fibroblasts are essential elements of myocardial tissue structure and function.In vivo, myocytes constitute the majority of cardiac tissue volume, whereas fibroblasts dominate in numbers.In vitro, cardiac cell cultures are usually designed to exclude fibroblasts, which, because of their maintained proliferative potential, tend to overgrow the myocytes. Recent advances in microstructuring of cultures and cell growth on elastic membranes have greatly enhancedin vitropreservation of tissue properties and offer a novel platform technology for producing morein vivo-like models of myocardium. We used microfluidic techniques to grow two-dimensional structured cardiac tissue models, containing both myocytes and fibroblasts, and characterized cell morphology, distribution, and coupling using immunohistochemical techniques.In vitrofindings were compared within vivoventricular cyto-architecture. Cardiac myocytes and fibroblasts, cultured on intersecting 30-μm-wide collagen tracks, acquire anin vivo-like phenotype. Their spatial arrangement closely resembles that observed in native tissue: Strands of highly aligned myocytes are surrounded by parallel threads of fibroblasts. In thisin vitrosystem, fibroblasts form contacts with other fibroblasts and myocytes, which can support homogeneous and heterogeneous gap junctional coupling, as observedin vivo. We conclude that structured cocultures of cardiomyocytes and fibroblasts mimicin vivoventricular tissue organization and provide a novel tool forin vitroresearch into cardiac electromechanical function.