Abstract Body: Introduction: The inability of the adult heart to regenerate results in prevalent morbidity and mortality related to myocardial infarction and heart failure. This lack of cardiac regeneration is driven by the loss of cardiomyocytes (CMs), with limited supporting endogenous CM renewal. While many individual regulators of CM proliferation have been implicated, the field lacks strategies to identify druggable proliferative signaling pathways and prioritize candidate therapeutics. Our goal is to predict and experimentally validate FDA-approved drugs and their respective mechanisms that regulate CM proliferation.
Methods: A logic-based differential equation model of CM proliferation signaling was integrated with drug-target interactions from a publicly available database (DrugBank) to simulate the effect of drugs on CM proliferation phenotypes (Binucleation, Cytokinesis, DNA Replication, Mitosis, and Polyploid). A virtual screen with knockdown combinations of regulators identified signaling mechanisms responsible for mediating the effect of drugs, and literature validation was performed against published experimental data investigating the drugs or the drug targets in CMs. Neonatal rat CMs were treated with the YAP-activating drug TT10 or drugs predicted to increase CM proliferation. Proliferation was measured by high-content microscopy and DNA replication and mitosis positive cells were identified from image analysis (CellProfiler) to discern CM proliferation from endoreplication.
Results: We identified 16 unique drug-target interactions predicted to regulate CM proliferation phenotypes. Four drugs were predicted to increase CM phenotypic proliferation outputs. Experimental validation confirmed lithium, a GSK3beta-antagonist, induces cell cycle activity in neonatal rat CMs as evidenced by increased Ki67 expression in cardiac Troponin T positive cells. The model predicts cyclin D is critical in mediating this response and subsequent experiments measured changes in cyclin D expression in response to lithium treatment. Retrospective analysis of clinical data (TriNetX and AERSMine) indicates more adverse events of congenital cardiac disorders were reported in patients exposed to lithium.
Conclusion: We identified lithium to promote DNA replication in CMs by upregulating cyclin D. This study advances the current knowledge of CM proliferation regulators by providing insight into new pathways targeted with existing drugs that can ultimately impact cardiac regeneration.