2026 Theses Doctoral

Engineering Fully hiPSC-derived Cardiac Tissues for Modeling Cardiovascular Disease and Injury

Zhuang, Richard Z.

There is a growing need for more advanced models of the human myocardium in cardiovascular disease research. Human engineered cardiac tissues have emerged as a promising platform to address these shortcomings by providing structurally and functionally relevant models of human heart tissue. Over the past two decades, engineered tissues have proven remarkably useful in recapitulating key aspects of human myocardial disease, predicting drug efficacy and cardiotoxicity, and even supporting long-term surgical implantation, bridging the gap between traditional preclinical models and native human pathophysiology. However, even the most advanced current models still do not fully recapitulate the structural, cellular, and functional complexity of native human myocardium. This dissertation addresses two major barriers to advancing human engineered cardiac tissues toward greater biological fidelity and translational relevance: the persistent immaturity of fully human stem cell-derived cardiac tissues and the absence of stable, functional vasculature within these systems.

In Aim I, we established a mature, fully hiPSC-derived engineered cardiac tissue platform for modeling inherited arrhythmia syndromes. Electrical stimulation promoted structural and functional maturation of fully hiPSC-derived engineered cardiac tissues, resulting in improved cellular alignment and sarcomeric organization, enhanced force generation and contractile kinetics, and increased sarcoplasmic reticulum calcium reserve. Using patient-derived and CRISPR-corrected isogenic hiPSCs, matured cardiac tissues were generated to model LQT8 and LQT2. Within this system, LQT8 tissues exhibited spontaneous early afterdepolarizations and sustained tachycardia-like activity, including monomorphic, polymorphic, and torsades de pointes-like waveforms that closely resemble clinical ECG morphologies of ventricular arrhythmia. LQT2 tissues remained comparatively stable under constant pacing but developed arrhythmias during dynamic rate acceleration, consistent with their clinically trigger-dependent presentation. Frequency-domain analysis and activation mapping further demonstrated re-entrant dynamics consistent with ventricular tachycardia-like behavior. Together, these findings show that functional maturation of fully hiPSC-derived engineered cardiac tissues enables the emergence of genotype-specific, physiologically triggered, ECG-like ventricular arrhythmia phenotypes.

In Aim II, we developed a fully hiPSC-derived vascularized engineered cardiac tissue platform to address the absence of integrated vascular networks in current engineered myocardium models. We show that incorporation of hiPSC-derived macrophages into engineered cardiac tissues composed of hiPSC-derived cardiomyocytes, cardiac fibroblasts, and endothelial cells promotes vascular organization, coordinated vascular-myocardial alignment, and improved cardiac contractile function. These benefits were sustained over long-term culture, during which macrophage-containing tissues maintained broad microvascular coverage, predominantly composed of capillary-scale structures distributed throughout the tissue body. Using this platform, we modeled sorafenib-induced vascular-dependent cardiac injury and found that vascularized tissues exhibited vascular regression, impaired relaxation-related contractile and calcium-handling kinetics, and altered inflammatory secretory responses that were not observed in non-vascularized tissues, identifying the microvascular compartment as a critical mediator of tissue-level drug-induced dysfunction. Finally, following subcutaneous implantation in a murine model, the engineered vascular networks demonstrated evidence of perfusion, host anastomosis, and improved graft integration, indicating that the microvascular structures formed in these tissues are capable of functional connection to actively perfused vascular networks.

Taken together, these studies advance human engineered cardiac tissues along two critical axes: functional maturation and vascularization. By establishing mature, fully hiPSC-derived cardiac tissues capable of reproducing clinically relevant arrhythmia phenotypes and vascularized cardiac tissues capable of modeling vascular-dependent injury and supporting host integration, this work provides a foundation for more physiologically relevant human myocardium models for disease modeling and cardiotoxicity screening.