Engineered Innervated Human Heart Tissues for In Vitro Studies of Cardiac Injury Response

About This Grant

Project Summary / Abstract Sympathetic neurons (SNs) are critical regulators of cardiac output in response to hemodynamic stress and are known to contribute to heart development and cardiomyocyte (CM) maturation. SNs are also required for cardiac regeneration after myocardial injury in neonatal mammals but become dysregulated with adult heart injury, leading to increased risk of fatal arrhythmias. Despite documented importance, human neuro-cardiac interactions have been understudied by researchers due to the lack of high-fidelity in vitro models that both accurately recapitulate the physiology of cardiac innervation and enable mechanistic studies using cell-specific functional assessments. The Bursac Lab has previously generated highly functional, three-dimensional (3D) engineered cardiac tissues (“cardiobundles”) made from neonatal rat ventricular myocytes or human induced pluripotent stem-cell derived CMs (hiPSC-CMs). Building on these results, I have recently developed and characterized a compartmentalized 3D coculture model of human cardiobundles innervated with hiPSC-derived SNs (hiPSC- SNs). Over the 4-week coculture, this novel neuro-cardiac model supports robust axonal ingrowth into cardiobundle compartment without detriment to cardiac contractile or electrophysiological function. Importantly, CMs within cardiobundles reliably respond to stimulation of SNs by presynaptic neurotransmitters, indicating the development of functional sympathetic innervation. For the proposed project, I will utilize this human in vitro model to test two hypotheses that functional innervation of cardiobundles will: 1) promote developmental maturation of hiPSC-CMs and neurocardiac junctions and 2) stimulate the regenerative response of cardiobundles to injury, thus allowing for detailed studies of underlying mechanisms. To test these hypotheses, in Specific Aim 1 I will utilize gene and protein expression profiling, functional assays, and genetically encoded sensors of membrane voltage, calcium, and neurotransmitter release to assess the time-course of structural and functional CM maturation and robustness of formed neurocardiac junctions. In Specific Aim 2, I will apply cryoablation and CM-specific injury protocols in multicellular cardiobundle models to assess the effects of SN innervation on CM and non-CM proliferation, matrix remodeling, neurocardiac functional recovery, and molecular mechanisms underlying the resulting regenerative or pathophysiological responses. Overall, this work will establish the first tissue-engineered model of anatomically representative, highly functional innervated myocardium for in-depth studies of the human neurocardiac development and diseases of the brain-heart axis.