Abstract 15800: Dissecting Cardiomyocyte-Fibroblast Communication During Homeostasis and Cardiac Fibrosis in a Compartmentalized Biomimetic Tissue Model

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Introduction: Cardiac fibroblasts (CFs) maintain cardiac structure and function by synthesizing and remodeling the extracellular matrix (ECM) found throughout the heart. Homeostatic maintenance of the ECM required for healthy tissue function depends on CF communication with cardiomyocytes (CMs). During cardiac fibrosis, signals resulting from tissue injury and dysregulated CF-CM communication promote CF differentiation into α-smooth muscle actin + (αSMA) myofibroblasts (MFs), which deposit excess ECM that mechanically impairs heart function. Given the challenges involved in parsing the dynamic and multifactorial heterocellular interactions underlying tissue homeostasis versus fibrosis, we engineered a compartmentalized, bilayer cardiac tissues where iPSC-derived CMs and CFs can be cultured on either side of a shared fibrous ECM to study CM-CF communication. Methods: Dextran vinyl sulfone (DVS) fibers were electrospun onto arrays of microfabricated PDMS wells. Matrix stiffness and alignment were controlled by modulating the speed of the collecting surface and UV light exposure, respectively. iPSC-CMs and primary human CFs were seeded onto opposing sides of the matrix. Immunostaining for αSMA was conducted to assess CF differentiation to MFs. Results: In CF monocultures on matrices varying in alignment and stiffness, MF differentiation was greatest on stiff (17.3 kPa) aligned matrices with exogenous TGFβ1 compared to soft (0.68 kPa) aligned matrices and both soft/stiff random matrices. We also observed increased nuclear YAP expression on stiff/aligned matrices, indicating altered mechanosensing in response to matrix properties. However, the presence of co-cultured CMs inhibited MF differentiation despite exogenous TGFβ1. MF differentiation was also impaired in CFs cultured on glass below matrix-seeded CMs, implying the role of protective paracrine signaling from CMs to CFs. Conclusions: We developed a microfabricated biomimetic coculture platform to examine CM-CF communication driving tissue homeostasis versus fibrosis. Specifically, we find that fibrous mechanical cues modulate YAP-mediated signaling and αSMA expression. Further, CM-CF paracrine signaling mitigates MF differentiation on aligned fibrous matrices.