Development of advanced in vitro models of the human heart recapitulating pump function and cardiac conduction dynamics

Cardiovascular diseases are the leading cause of mortality worldwide and represent a growing global health burden. However, therapeutic development remains slow and costly, partly due to the limited predictive power of animal models in preclinical research. Human-based in vitro systems provide a promising alternative to this limitation, particularly through human pluripotent stem cell (hPSC) technologies, which enable the generation of patient-specific cardiac cells. Despite these advances, hPSC-derived cardiomyocytes exhibit an immature, foetal-like phenotype, highlighting the need for advanced models that better recapitulate the structural, biological, mechanical, and electrophysiological environment of the human heart.
This dissertation addresses this need by developing advanced hPSC-derived in vitro cardiac models with increased physiological and structural complexity. Cardiac chamber models were engineered to recapitulate the pump function of the heart, together with conduction-system-inspired constructs to study electrical propagation and pacing dynamics, thereby enhancing the relevance of human-based platforms for disease modelling and drug screening.
This thesis presents a novel bioreactor platform for the scaffold-free engineering of cardiac chambers, referred to as mini-hearts. Functional characterization of these mini-hearts was achieved through non-invasive measurements of volumetric displacement, enabling confirmation of pump function and estimation of physiologically relevant hemodynamic parameters in the absence or presence of drug compounds. A comprehensive review of the role of active mechanical loading in the heart and its in vitro replication is also provided. To study the effects of mechanical loading on the mini-hearts, dynamic preload was introduced via cyclic volumetric actuation, resulting in improved pump performance and structural remodelling. The scalability of cardiac chamber engineering was further enhanced by translating the fabrication technology to a well-plate format, increasing throughput and enabling modular tissue integration, which was leveraged to explore the incorporation of an outer epicardial layer. Finally, patterned atrioventricular or sinoatrial co-culture constructs were developed to model cardiac conduction system interfaces, revealing geometry-dependent electrical propagation and drug-induced arrhythmic behaviour. Collectively, this work advances engineered human cardiac models toward more predictive and translational preclinical applications.