Experimental Study Of Venoarterial Extracorporeal Membrane Oxygenation Improves Cardiac Function After Acute Myocardial Infarction In Rats

Objective:Acute myocardial infarction（AMI）is a disease of acute ischemic necrosis caused by coronary artery occlusion with rapid onset and high mortality.As an important means of mechanical circulation support,Venoarterial extracorporeal membrane oxygenation（VA ECMO）is widely used in the adjuvant therapy of patients with severe AMI,and can significantly improve the clinical outcome and prognosis of patients.However,its potential myocardial protective mechanism remains unclear.This study aims to provide a theoretical basis for the clinical treatment of AMI by exploring the efficacy and mechanism of VA ECMO in AMI.Methods:1.The effects of VA ECMO on hemodynamics,myocardial injury,myocardial fibrosis and cardiac function in AMI were investigated by establishing a rat model of VA ECMO adjuvant therapy for AMI.2.Single cell transcriptome sequencing（Sc RNA-seq）technique was used to explore the mechanism of VA ECMO alleviating myocardial injury in AMI.3.The rat models of AMI and ECMO were established in vivo,and the Oxygen and glucose deprivation（OGD）models of rat cardiomyocytes（H9c2）,rat primary cardiomyocytes（RCm）and human pluripotent stem cell-derived cardiomyocytes（hi PS-CM）were established in vitro to verify the differential expression of cold-induced RNA binding proteins（CIRBP）before and after ischemia.On this basis,the role of CIRBP in post-AMI inflammation and its potential mechanism were further evaluated by immunofluorescence,WB and Masson staining.4.The effects of gene silencing on myocardial injury,inflammatory response,cardiac function and myocardial fibrosis in AMI were verified by gene silencing CIRBP(Cirbp^-/-).5.The specific CIRBP antagonist C23 was used to investigate the effects of blocking extracellular CIRBP binding to Toll-like receptor 4（TLR4）pathway on myocardial injury,cardiac function and myocardial fibrosis.6.By introducing glucocorticoid dexamethasone（Dex）into the rat model of VA ECMO adjuvant treatment of AMI to explore whether VA ECMO combined with Dex can further enhance the myocardial protective effect of VA ECMO.Results:1.In the rat model of VA ECMO assisted AMI,it was found that VA ECMO played a role in stabilizing hemodynamics,alleviating myocardial injury in AMI,improving cardiac function and myocardial fibrosis.2.Through Sc RNA-seq analysis,it was found that neutrophils could be divided into three cell groups,and there was a significant difference in the proportion of neutrophils subsets between AMI and ECMO groups.Among them,neutrophils 1 and3 with high expression of Gpr84⁺were dominant in AMI group,and 2 subsets with high expression of Alpl⁺Rhov⁺were dominant in ECMO group.Further GO enrichment analysis of neutrophil subsets showed that the pro-inflammatory effect of Cluster-2 neutrophil subsets was weak and significantly correlated with VA ECMO.3.Animal and cell experiments have found that CIRBP is the early mediator of inflammation and organ damage after AMI.The ischemic process of tissues and cells can promote the production and release of CIRBP,while VA ECMO can significantly reduce the level of CIRBP released from the ischemic part of the heart.4.Through WB,immunofluorescence and Masson staining,it was found that CIRBP mediated neutrophil infiltration and pro-inflammatory factor release in AMI,thus aggravating myocardial injury,increasing myocardial infarction size and myocardial fibrosis.5.The AMI model was established in Cirbp^-/- rats,it was found that the absence of CIRBP could reduce myocardial injury,myocardial infarction size and inflammation in AMI,and improve cardiac function.6.Animal experiments have found that specific CIRBP antagonistic peptide C23can reduce inflammatory response,myocardial injury and improve cardiac function in AMI by blocking extracellular CIRBP binding to TLR4.7.Through molecular experiments on the animal model of VA ECMO combined with Dex,it was found that Dex combined with VA ECMO could further reduce myocardial injury,myocardial apoptosis and improve cardiac function.Conclusion:1.AMI can promote the release of CIRBP,recruit inflammatory cell infiltration dominated by neutrophils by binding with TLR4,and then mediate immune inflammatory response and myocardial injury of AMI.2.The potential mechanism of cardioprotective effect of VA ECMO is to reduce the release of CIRBP,and then reduce the excessive inflammatory response and the transformation of proinflammatory subsets after myocardial infarction with proinflammatory neutrophil infiltration as the core.The main manifestations are to reduce myocardial infarction size,improve cardiac function and ventricular remodeling,and prevent heart failure after myocardial infarction.3.Studies have revealed the mechanism of VA ECMO in AMI,and the key protein CIRBP is expected to become a new target to reduce myocardial injury and improve cardiac function.4.Gene silencing of CIRBP or the use of specific CIRBP antagonistic peptide C23 can significantly reduce myocardial injury caused by AMI,which provides a reliable basis for future clinical transformation,and is expected to become a new drug for the treatment of AMI.5.VA ECMO combined with Dex therapy can further enhance the myocardial protective effect of VA ECMO on AMI..