Perfusable Engineered Heart Tissues as Models of Vascular-Myocardial Interaction and Cardiac Repair

Abstract

Cardiovascular disease remains the leading cause of mortality worldwide, yet our ability to engineer effective cardiac therapies and physiologically relevant in vitro models remains limited due to an inability to recapitulate the complex interplay between the vasculature and the myocardium. The heart is a highly metabolically active organ that depends on dense vascularization for oxygen and nutrient delivery, as well as on continuous endothelial-myocardial crosstalk to regulate homeostasis and function. However, achieving adequate vascularization remains a fundamental challenge across cardiac tissue engineering. In regenerative contexts, existing approaches have fallen short in producing the vascular density and tissue thickness necessary to support large-scale cardiac repair, while in vitro models have largely failed to integrate perfusable vasculature that allows for hemodynamic loading and multicellular vascular-myocardial interactions. To address this challenge, this dissertation reports the development of two complementary platforms: (1) thick, highly vascularized engineered tissues to promote rapid host vascular integration for cardiac regeneration applications and (2) perfusable engineered heart tissues (EHTs) to investigate the role of vascular interaction and hemodynamic forces on cardiac function and maturation. First, to generate thick, highly vascularized tissues, we developed a modular fabrication approach in which individually patterned collagen membranes are stacked into multilayer constructs. These constructs maintained structural integrity and patent endothelialized lumens throughout one week of culture, supported angiogenic remodeling, and demonstrated uniform perfusion across all layers. Transcriptional profiling revealed upregulation of gene programs associated with vascular development and angiogenesis compared to control which relied on non-perfusable self-assembled vascular networks. Upon implantation onto infarcted rat hearts, perfusable multilayer microvessel grafts achieved significantly greater perfused vascular density and perfusion rate than controls with only self-assembled vasculature. This study demonstrated the critical role of perfusable vasculature in promoting rapid host-vascular integration of implanted engineered tissues. Building on this foundation, we next developed a perfusable, collagen-based EHT which incorporates hiPSC-derived cardiomyocytes and endothelial cells within the bulk matrix and a central lumen that can be perfused, pressurized, and endothelialized. These constructs exhibited spontaneous contractile activity and a Frank-Starling-like response to increased preload. Transcriptional analyses revealed that lumenization shifted EHTs toward enhanced metabolic specialization and reduced inflammatory signaling, while intraluminal pressure further drove metabolic reprogramming consistent with an adaptive response to mechanical load. Endothelialization of the lumen produced a stimulus-responsive endothelium which drove tissue-level transcriptional changes consistent with paracrine vascular-myocardial signaling. Together, this work establishes two physiologically relevant engineered cardiac tissue platforms and advances our understanding of how vascularization influences cardiac repair and function, providing a foundation for future applications in disease modeling, therapeutic screening, and improved cardiac regeneration.