Bioprinted Human Ventricles for In Vitro Modeling of Cardiac Arrhythmias

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Over the past 40 years nearly 45% of drugs withdrawn from the market have been due to cardiac safety concerns, contributing to the ever increasing cost and declining productivity of the biopharma R&D process. While the mechanisms of drug-induced cardiotoxicity vary widely by drug and target, the most common and dangerous manifestation is cardiac arrhythmia and sudden cardiac death. The biopharma industry has heavily invested in new tools that are sensitive to cardiotoxic effects, however, current preclinical models are a compromise in the structural, compositional, and functional complexity necessary to recapitulate and be predictive of human cardiac electrophysiology. Further, understanding how patient-specific risk factors including genetic predisposition, age, sex, and underlying cardiovascular disease (e.g. fibrosis, ischemia, infarction) contribute to a drug-induced proarrhythmogenic state requires the development of entirely new in vitro models of impulse conduction disorders. In this proposal our objective is to develop a new bioengineered human ventricle as a predictive in vitro model for identifying drug-induced proarrhythmogenic risks in the human heart. To overcome current limitations, FluidForm, Inc in collaboration with Carnegie Mellon University will develop a new freeform reversible embedding of suspended hydrogels (FRESH) 3D bioprinted left ventricle model that recreates the laminar architecture of ventricular myocardium and has tailored structure and composition to mimic proarrhythmogenic disease states. Our preliminary data establishes that we can build a functional ventricle with circumferential myofiber alignment, anisotropic action potential propagation, distinct arrhythmia features including rotors and multiple propagating waves, and complex biomechanical responses including wall thickening. Here we will improve ventricle performance for use in the biopharma R&D process via two research aims. First, we will establish baseline sensitivity of the FRESH 3D bioprinted human ventricle model to known proarrhythmogenic compounds and generate industry-standard does-response curves. Second, we will demonstrate tunable sensitivity by controlling cardiomyocyte and collagen architecture to mimic fibrotic disease and incorporate iPS-derived human cardiomyocytes with known conduction mutations. This will allow us to achieve patient-specific disease models that show dose-response curves that are left-shifted for proarrhythmogenic compounds. Phase I proof-of-concept success will provide a strong foundation for a Phase II SBIR project that will validate the complete FRESH 3D printed ventricle model in an in vitro high-content imaging platform to assess electrophysiology and biological response, and provide a critically needed, industry- leading capability to accurately predict human arrhythmias in drug development.