Abstract 12329: Checkpoint Kinase 1 Protein Therapy Stimulates Endogenous Cardiomyocyte Renewal and Cardiac Repair in a Porcine Model of Myocardial Ischemia/Reperfusion Injury

Objective: To investigate the impact of recombinant human checkpoint kinase 1 (rhCHK1) on cardiomyocyte renewal and myocardial repair after myocardial ischemia/reperfusion (I/R) injury in swine. Methods: Quantitative phosphoproteomics profiling was performed on infarct border zone of neonatal myocardium, and kinase-substrate network analysis using iGPS algorithm revealed CHK1 kinase with enriched substrates and upregulated phosphorylation levels. Swine myocardial ischemia/reperfusion injury was induced by ligating the left anterior descending coronary artery for 60 minutes, and followed by reperfusion. Immediately after reperfusion, rhCHK1 protein (1mg/kg) dissolved in hydrogel or equivalent hydrogel was injected into the infarcted border zone. The therapeutic efficacy of rhCHK1 post I/R injury was evaluated by ECG, echocardiography, MRI, hematological indices and immunofluorescence. Results: Intramyocardial injection of rhCHK1-hydrogel efficiently delivered rhCHK1 to the cardiomyocytes surrounding the infarcted area of pig hearts without affecting other organs. A single administration of rhCHK1 protein (1mg/kg) prominently stimulated cardiomyocytes proliferation, reduced cardiac inflammation and improved vascularity 3 days after I/R. At 28-days post rhCHK1-hydrogel therapy, improved cardiac function, reduced infarct size and cardiac scar area, and attenuated ventricular remodeling were evidenced in I/R swine. Mechanistically, rhCHK1 stimulated CMs renewal and cardiac repair by activating mTOR/CTHRC1/P70S6K signaling pathways. Conclusion: Our study demonstrates that myocardial injection of rhCHK1 could promote cardiomyocyte proliferation, inhibit local myocardial inflammation and promote angiogenesis to facilitate myocardial repair and cardiac function after I/R injury in adult pigs through activating mTOR/CTHRC1/P70S6K signaling pathways.