Abstract Body: Background: The limited proliferative capacity of cardiomyocytes (CMs) is a major barrier to recovery after myocardial infarction (MI), as hypoxia-induced CM death leads to permanent loss of contractile tissue. Enhancing CM cell cycle activity after injury may restore cardiac function. We previously demonstrated that cycling CMs exhibit upregulation of Wilms’ Tumor 1 (WT1) and genes associated with retinoic acid (RA) synthesis, resembling reactivated epicardial cell expression patterns. WT1 and RA are known to be cardioprotective, but their CM-specific roles in cycling and repair remain poorly defined. To address this, we developed a WT1 network model to identify key regulators of cardiac repair. Model predictions were further investigated using our novel WT1 knockout mouse model.
Hypothesis: We hypothesize that WT1+ CMs retain the ability to re-enter the cell cycle and facilitate cardiac repair after injury by modulating the cardiac microenvironment through paracrine signaling.
Methods: We developed a logic-based differential equation model to investigate WT1 contributions to cardiac regeneration after injury. Simulations of knockdown and overexpression were performed on the injury model to predict key regulators of DNA replication and epithelial-mesenchymal transition. Validation using primary literature (n = 49) compared our simulations to experiments across cell types. To test model predictions, we developed a mouse model that ablated WT1 in adult Ki67+ cycling CMs. GFP+ cycling cells and infarct sizes were quantified to assess WT1’s regulation of CM cycling.
Results: The model predictions aligned with 84% of experimental results in cancer cell lines and 75% in non-cancer cell lines, suggesting that the hypoxia-induced WT1-RA signaling axis is critical for DNA replication. Preliminary results show increases in CM cycling after the loss of WT1 from Ki67+ CMs, compared to littermate controls (Welch’s t-test, p=0.114, N=3). Infarct sizes were similar between groups.
Conclusions: Our literature-informed model suggests that WT1 regulates signaling networks controlling CM cell-cycle dynamics after injury. Increased cycling following WT1 deletion from Ki67+ CMs suggests that the loss of WT1 from cycling CMs may promote cycling in neighboring CMs.