Mass Cytometry Based Studies Of Immunomodulatory Network In Mice After Myocardial Infarction

Backgroud and purpose:Cardiovascular disease is one of the refractory diseases harmful to human health,and myocardial infarction is the most common cause.Although drugs and surgical treatment reduced the early mortality of myocardial infarction,some patients eventually developed heart failure because the necrotic myocardium was difficult to repair.Acute myocardial infarction(AMI)causes a strong inflammatory response in the early stage,which affects the process of tissue repair and cardiac remodeling.The activity of immune cells in the heart is complex and changeable,and they can promote tissue repair under appropriate conditions,but excessive inflammatory response can lead to further tissue damage.Mesenchymal stem cell(MSC)can improve the prognosis of myocardial infarction by regulating the activity and distribution of immune cells during myocardial infarction.Mass cytometry is using the principle of mass spectrum of single-celled multi-parameter detection of streaming technology,it has the traditional high-speed analysis of characteristics of flow cytometry and high resolution,it can test hundreds of different parameters at the same time,no interference between the channel and has less noise signal,so it’s a new development direction of flow cytometry technology,will help us to explore the immune subsets after myocardial infarction.The purpose of this study is to systematically describe the dynamic changes of immune cells in the heart after acute myocardial infarction,to explore the regulatory effect of mesenchymal stem cells on the immune microenvironment of myocardial infarction,and to screen out cell subsets that have an important impact on the prognosis of myocardial infarction.Methods and results:The mice were randomly divided into normal control group,DMEM treatment group and MSC treatment group.The acute myocardial infarction model was established by ligating the left anterior descending branch of coronary artery.The myocardial infarction mice were treated with DMEM and MSC,respectively.The infarcted area,peripheral area and peripheral blood samples of normal control group,1day and 3 days after myocardial infarction were taken to prepare single cell suspension.The immune atlas of myocardial infarction and MSC treatment were made by mass cytometry and a variety of data analysis methods.We used 42 cell markers to classify immune cells and obtained 18 subsets,evaluated their dynamic changes after myocardial infarction and MSC treatment,then screened out BST2+ macrophage subsets.Through mass cytometry analysis,flow cytometry detection and immunofluorescence staining,it was confirmed that the number and percentage of BST2+ macrophage increased significantly after MSC treatment.At the same time,we also speculated that this subgroup may be a subgroup of macrophages differentiated by peripheral monocytes after entering the heart under the influence of the local microenvironment of myocardial infarction.We selected this subgroup by flow cytometry and co-cultured with neonatal mouse cardiomyocytes,and found that BST2+macrophage can significantly reduce cardiomyocyte apoptosis,so it may play an important role in myocardial protection.Conclusion:The subsets of immune cells in the heart changed dramatically after myocardial infarction,and the distribution of some subsets in the heart was also changed after MSC treatment.BST2+ macrophage may be an important target for promoting myocardial infarction repair due to their ability to reduce cardiomyocyte death.