Abstract Body (Do not enter title and authors here): Modeling cardiac disease has been a central goal in tissue engineering. Engineered human cardiac tissues now serve as valuable platforms for studying heart tissue replacement, disease modeling, and advancing therapeutic discovery. However, we are yet to recreate the complex and functional human myocardium in vitro, particularly with respect to integrating perfused vasculature and immune components. The lack of vasculature continues to significantly limit the ability to study conditions that involve disruptions in blood flow, such as coronary heart disease and ischemia-reperfusion injury. To this end, we engineered an in vitro model of human myocardium from a single iPSC line encompassing the different cellular landscape of the native myocardium to more faithfully recapitulate the functionality of adult human heart.
The vascularized cardiac tissues were generated using WTC11-hiPSCs differentiated into cardiomyocytes (iCM), cardiac fibroblasts (iCF), endothelial cells (iEC) and resident macrophages (irMf) and assessed for the appropriate cell-identity markers via immunofluorescent staining. Tissues were generated by encapsulating cells in fibrin hydrogel and culturing the resulting cell-hydrogel constructs stretched between two elastic pillars. The tissues were cultured for 7 days and electrically stimulated for another 7 days. Immunofluorescent staining was performed to assess capillary formation. We demonstrate that hiPSC-derived endothelial cells have the capacity to form dense vascular networks that are aligned with hiPSC-cardiomyocytes in the direction of tissue contraction. After 7 days of culture, the tissues were highly vascularized with an interconnected network of capillaries demonstrating active angiogenic sprouting. We further observed a close interaction between iCF and iECs with fibroblasts adopting a perivascular-like morphology and wrapping around capillaries with open lumens. Finally, the incorporation of hiPSC-derived macrophages and application of electrical stimulation enabled long-term survival of vascular networks and increased the network complexity. This work paves the way for the development of autologous vascularized cardiac tissues, to support patient-specific studies of cardiovascular diseases.