The Role Of Autophagy On The Treatment Of Ischemic Cardiomyopathy By Induced Pluripotent Stem Cell Transplantation

Background: As the leading cause of death in developed countries and one of the major disease burdens in developing countries,cardiovascular disease,especially acute myocardial infarction(AMI),seriously affect the quality of life of the patients.In recent years,more researches have shown that stem cells transplantation have a therapeutic effect on AMI,which including embryonic stem cells(ESC),bone marow mesenchymal stem cells(MSC),induced pluripotent stem cells(i PSC)et al.These studies suggest that stem cell transplantation can improve heart function and may reduce the infarct size,mortality and morbidity after acute myocardial infarction(AMI).i PSC has a wider prospects for application because that it comes from the body cells and avoids immune rejection thus it not only has the totipotent similar to ESC,but has no the ethical controversy.Autophagy is a process that evolves the body by degradating the cytoplasmic components to maintain the cell survival and the homeostasis in the tissues.Recently,researches have shown that autophagy can either maintain stem cells to a relatively undifferentiated state or promote the differentiation process.Then,what the probablely role of autophagy on the process of i PSC transplantation intervention in AMI,and whether it can be used as a mechanism of the intervention in AMI are not yetknown.Objective: To investigate the possible role of autophagy after i PSC transplantation in a porcine model of AMI,and to further explore its possible mechanism.Methods:1?To establish a porcine model of AMI:20 pigs,weighing 23.52 ± 2.33 kg,were randomly divided into three groups: 4 in sham control group,8 in phosphate buffer(PBS)group and 8 in i PSC transplantation group.PBS group and i PSC transplantation group establish the AMI models by occlusion of the left anterior descending coronary artery(LAD).Verify the success of AMI animal model by electrocardiogram,plasma troponin and left ventricular angiography.2?The i PS cells transplantation:Cultivating a great number of i PSCs originates from porcine before the establishment of AMI model.1 week after the AMI model creation,allogeneic undifferentiated i PS cells(2x107 cells/2 ml)or phosphate buffered saline(PBS,2 ml)were injected into the Myocardium of the infarcted zone(IZ)and the border zone(BZ)in both i PSC group and PBS group by opening the chest.Porcine in sham group only received thoracectomy without any intervention and placement of catheter and balloon without blocking.3? The animals were sacrificed and specimen were handed:Seventh week after cell transplantation,animals were killed,and the heart was taken out,which be devided into the infarct zone IZ,the area around the infarct zone BZ and the remote zone RZ.Observing the myocardial infarction and normal myocardium appearance by TTC staining and the histopathological change by HE staining.Western blot was used to detection of autophagy-related protein LC3,Atg5,Beclin1 and Cx43,MMP9,ANP,etc.Result:1?ECG and cardiac angiography showed that the porcine model of AMI was succeed.2?TTC staining of heart specimens shows that infarct myocardial size of i PS group was significantly reduced compared with PBS group(P = 0.01);HE staining and Masson's Trichrom staining showed there were more inflammatory cell infiltration,and no viable myocardium cells in the PBS group.Compared with PBS group,there were less fibrosis and inflammatory cell infiltration and more viable myocardium islands in i PS group.i PS cells transplantation decreased the fibrosis area of border zone compared with PBS group(P<0.05).Electron microscopic examination also found that i PS cell transplantation can ameliorate the alteration of ultrastructure after MI.3 ? autophagy markers detection: The expression of LC3,Atg5 and Beclin1 was significantly enhanced in infarct zone IZ and in borden zone BZ compared with those in remote zone RZ in PBS group.The expression of autophagy was significantly enhanced in IZ compared with it in RZ in i PS group.The expression of autophagy was significantly increasing in IZ in i PS group compared with it in IZ in PBS group,p = 0.058.4?Cx43 expression of myocardial cells in IZ and BZ was significantly lower than in RZ in PBS group,IZ compared with RZ was statistically significant(P <0.05).Cx43 expression in cardiomyocyte in IZ and BZ were significantly lower than in RZ in i PS group(P <0.05).The expression of Cx43 in IZ in i PS group significantly increasing than PBS group.5?MMP9 expression of myocardial cells in IZ was significantly higher than RZ in PBS group(P <0.05).MMP9 expression of myocardial cells in IZ and BZ was relatively Lower than RZ in i PS group,but not statistically significant.MMP9 expression in IZ and BZ in iPS group were significantly lower than same area in PBS group(P <0.05).6?ANP expression of myocardial cells in IZ and BZ were significantly higher than RZ(P <0.05)in PBS group.ANP expression of cardiomyocyte in IZ was relatively lower than in BZ and RZ(P<0.05)in i PS group.ANP expression in IZ in i PS group were significantly lower than same area in PBS group(P <0.05).Conclusion:1?i PS can cause upregulation of autophagy in the process of intervention in AMI.2?i PS cells may induce the expression of Cx43 by autophagy,through which it can increased myocardial cells,which have an impact on cardiac electrophysiology.3?i PS cells possibly induced the expression of MMP9 in myocardial cells through autophagy,thereby improving myocardial remodeling.4?i PS cell transplantation can cause ANP down regulation expression in myocardial cells,but it is still to be explored further to prove whether it is relation to autophagy.