Abstract 15845: Microfabricated Anisotropic Tissue Bundles for the Production of 3D Cardiac Tissue at Scale

Abstract

Rationale: Following myocardial infarct, tissue ischemia and cardiomyocyte (CM) death trigger inflammation followed by extracellular matrix (ECM) remodeling mediated by cardiac fibroblasts (CF). The cardiac tissue engineering field aims to replace damaged myocardium and restore normal cardiac function. The ECM’s high degree of structural anisotropy and the organization of resident cell populations are critical features necessary to recapitulate healthy myocardial function. Thus, there is a critical need for biomanufacturing technologies that can organize ECM and multiple, distinct cell types with microscale precision in tissue grafts of translationally relevant scale. Here, we propose a scalable material strategy for fabricating individual myofiber-like tissues with anisotropic organization and relevant cell populations comparable to native myocardium. Methods and Results: Microchannels of varying widths were perfused with fibrin (20mg/mL fibrinogen with 1U/mL thrombin supplemented with 0.05mg/mL aprotinin for the first 3 days of culture) or a mixture of fibrin and collagen (10mg/ml fibrinogen with 1U/mL thrombin and 2mg/ml collagen). Hydrogels contained up to 40 million/mL cells (25% CFs and 75% CMs) and 8 vol% RGD-functionalized dextran-vinyl sulfone (DVS) electrospun fibers. Microchannel perfusion of composite hydrogel solutions resulted in flow-induced alignment of DVS fibers across all channel sizes (200, 300, 400, and 500 μm), although fiber alignment decreased with increasing channel size. Tissue size, cell spreading, CM contraction, and myofibril development and alignment varied with channel size, cell density, and hydrogel formulation over two weeks inculture. Overall, hydrogel composites with aligned fibers and a combination of CMs and CFs resulted in anisotropic, myofiber-like tissue structures. Conclusion: In this study, we developed a microfabrication approach to produce anisotropic myofiber-like bundles using composites of naturally derived ECM and synthetic polymeric fibers that can be flow-aligned within microfabricated microchannels. This approach allows us to fabricate unit cell tissues of desired size and alignment that can be combined into a larger tissue construct for therapeutic applications.