| BackgroundThe incidence of acute myocardial infarction(AMI)is frequently increasing worldwide,that seriously affects human health and brings huge medical and economic burden.Early diagnosis and prognosis evaluation of AMI is still a hot research topic.Coronary heart disease is a syndrome that is a continuous process from atherosclerosis(AS)occurrence to end-stage heart disease.The inflammatory immune response is involved in the whole process from initial stage to the end stage.Taking part in the inflammatory response,Tenascin-C plays an important role in the occurrence and development of coronary heart disease.As a large glycoprotein,Tenascin-C is known to be expressed in ECM.Tenascin-C is usually expressed at higher level in the heart during embryonic development,but not normally expressed in the adult.However,it transiently reappears under various pathologic conditions including AMI,hibernation,myocarditis,and dilated cardiomyopathy.That suggests a potential role of Tenascin-C in the progression of cardiovascular disease.Tenascin-C has been shown to play a vital role in dilated cardiomyopathy,aortic dissection,rheumatic heart disease and other cardiovascular diseases.It is considered a novel marker for the diagnosis and prognosis of these cardiovascular diseases.Tenascin-C can promote the progress of AS,and acute ST segment elevation myocardial infarction(STEMI)is the extreme state of AS progression and plaque changing from stability to instability.So the role of Tenascin-C in early diagnosis,prognosis evaluation of acute myocardial infarction was discussed in the first part of this study.At present,the conventional therapies of AMI including drug therapy,interventional therapy,and surgical therapy without solving the key problem of cardiomyocyte loss,can not completely prevent or reverse the pathological process,and as a result the occurrence of cardiac remodeling and heart failure can not be prevented eventually.A breakthrough in this field is stem cell transplantation in AMI recently.Most of the basic studies have proved that stem cell transplantation is effective,but clinical studies found no significant improvement in cardiac function.With the development of the study,it has been found that the stem cells homing to the infarct area after transplantation were less,and the rate of differentiation and survival was low,which significantly weakened the effect of stem cell transplantation.The existence of problems prompted people to make new exploration in the field of stem cell therapy in AMI.In order to improve the therapeutic effect,more exploration should be made in the field.Bone marrow mesenchymal stem cells(BMMSC)might be considered a better choice of the cells due to their convenience,without an ethical problem or immune rejection.As an indicator of inflammatory immunization,Tenascin-C not only can be considered a marker for early diagnosis and prognosis evaluation of STEMI,but also promotes the adhesion,migration and differentiation of various cells.It has been found in our previous experiment that Tenascin-C has protective effect on BMMSC and can promote the migration of BMMSC.The second part of this study is to build AMI mouse model,and to explore the role and mechanism of Tenascin-C in the BMMSC transplantation for AMI mice,so as to provide a new theoretical basis and therapeutic target to improve the effect of BMMSC transplantation.Part one: The role of Tenascin-C in early diagnosis and prognosis evaluation in STEMI patientsObjective To explore the role of Tenascin-C in early diagnosis and prognosis evaluation in STEMI patients.Methods We recruited 113 STEMI patients who were admitted to Department of Cardiology of the First Affiliated Hospital of Dalian Medical University and underwent successful percutaneous coronary intervention(PCI)during June 2015 to July 2016.Control group included 22 patients without coronary artery disease confirmed by coronary angiography.The venous blood was drawn from 43 STEMI patients at the first,second,third,fifth,and seventh days after onset of symptom and on the third day in other patients.The ELISA method was used to detect the concentrations of Tenascin-C,TC,TG,HDL-C,LDL-C,hs-CRP,c Tn I,BNP,and so on.Echocardiographic examination by GE Vivid 7 was performed in all patients to assess the cardiac function.Major adverse cardiovascular event(MACE)was observed during 12 months follow up in all patients.Statistical analysis was performed using SPSS19.0.The continuous variables were presented as the mean ± standard deviation(S.D)and the categorical variables were expressed as the percentage.Comparisons of continuous variables were analyzed by one-way analysis of variance(ANOVA)with LSD analysis and categorical variables between groups were performed with the chi-square test.The correlation analysis was performed by Spearman correlation test.Further receiver-operating characteristic(ROC)analysis was used to determine an optimal cut-off value of serum Tenascin-C level for prediction of MACE.Event-free survival curves for MACE were constructed by the Kaplan-Meier and statistical differences between curves were assessed by log-rank test.In addition,Cox proportional hazards analysis was performed to identify independent predictors of MACE during 12 months follow-up after AMI.A value of P<0.05 was considered to be statistically significant.Results1.Serum Tenascin-C levels in STEMI patients: The serum Tenascin-C levels in 43 STEMI patients were(46.51±24.37)ng/ml on the first day,(66.87±34.44)ng/ml on the second day,(97.49±41.24)ng/ml on the third day,(86.89±38.06)ng/ml on the fifth day,and(70.87±34.86)ng/ml on the seventh day,respectively.The serum Tenascin-C levels were observed to increase from the first day after the onset of disease,peaked on the third day,and then gradually decreased.2.The serum Tenascin-C levels in STEMI patients were positively correlated with hs-CRP,c Tn I and BNP,and the correlation coefficients were 0,0,0.003 respectively(P<0.05).The serum Tenascin-C levels were negatively correlated with e GFR,and the correlation coefficient was-0.002(P<0.05).3.Results of 12 months follow-up: No patient was lost during the follow-up.There were31 cases of MACE,including 6 cases of cardiac death(5.3%),18 cases of heart failure or heart failure aggravation(15.9%),7 cases of recurrent myocardial infarction(6.2%).4.Comparison between patients in MACE group and non-MACE group: the proportion of IRA to RCA,LVEF,and e GFR,were lower in MACE group than that in non-MACE group(P<0.05).However,BNP,hs-CRP,peak c Tn I,Tenascin-C,the proportion of IRA to LAD,the delayed time before reperfusion,the proportion of Killip grade?2 were higher in MACE group than that in non-MACE group(P<0.05).5.Receiver-operating characteristic(ROC)analysis of serum Tenascin-C for predicting MACE: For prediction of MACE,the AUC of the serum TN-C level was 0.991(95% CI0.978~1.000,P<0.05),which resulted a good predictor value in predicting MACE for STEMI patients.The best cut-off value for predicting MACE was 100.18 ng/ml,with a sensitivity of 96.8% and specificity of 96.3%.6.Kaplan-Meier analysis: Increased Tenascin-C levels were associated with higher number of MACE during follow up.7.Cox proportional hazards model analysis: Serum Tenascin-C level was an independent predictor of MACE for STEMI patients during a follow-up of 12 months after AMI(RR=1.017,95% CI 1.011~1.022,P<0.05).In addition,other variables including hs-CRP(RR=1.015,95% CI 1.002~1.028,P<0.05),c Tn I(RR=1.005,95%CI 1.000~1.009,P<0.05),and BNP(RR=1.000,95% CI 1.000~1.001,P<0.05)were also found to be independent predictors of MACE.Conclusions Detection of serum Tenascin-C levels is helpful for early identification and diagnosis of AMI.The serum Tenascin-C levels in STEMI patients were correlated with hs-CRP,c Tn I,BNP,and e GFR.The serum Tenascin-C levels had a good value in predicting MACE for STEMI patients,and may become an independent predictor of MACE in STEMI patients during a follow-up of 12 months after AMI.Repair in Acute Myocardial Infarction Mice Part two: The Role and Mechanism of Tenascin-C in cardialObjective To explore the role and mechanism of Tenascin-C in the BMMSC transplantation in AMI mice.Methods The BMMSC from C57BL/6 mice were isolated,cultured and passaged according to the methods described previously,with some modifications.Further,BMMSC were identified by flow cytometry.The AMI mice were prepared and confirmed by echocardiography and pathology examinations.The cardiac function of AMI mice was detected with VEVO 1100 ultrasound system for small animals.The effects of BMMSC transplantation and Tenascin-C treatment on the cardiac function of AMI mice were evaluated with VEVO 1100 ultrasound system.The computer-aided image analysis system(Image-Pro Plus)was used for the measurement and comparison of the areas of infarcted myocardium.The concentrations of TNF-?,TGF-?,IL-6,IL-12 and other inflammatory factors in plasma of AMI mice were determined by ELISA.The GFP labeled BMMSC were injected into the AMI mice.1 week later,a frozen section was made from the heart,and the cell homing was observed under the fluorescence microscope.Statistical analysis was performed using SPSS19.0.The continuous variables were presented as mean ± S.D.The categorical variables were expressed as the percentage.The cardiac function,infarcted myocardial area,inflammatory factor levels and cell homing rate were compared between different groups with one-way analysis of variance(ANOVA)with LSD analysis.The survival rate between the experimental group and control group was compared with chi-square test.A value of P<0.05 was considered to be statistically significant.Results1.The cells obtained from the mice bone marrow were CD29+(96.9%),CD34+(96.3%),CD44+(40.9%),and CD45–(0.7%),which confirmed that these cells were BMMSC.2.In AMI group,the myocardium in the ligature area became thinner,the local motion became weaker,and the local fibrosis was seen.It was confirmed by echocardiography that the cardiac function of the AMI group was significantly lower than that of the control group(P<0.05).The AMI mice were successfully prepared.3.The cardiac function of the AMI mice in the BMMSC transplantation group was better than that in the control group(P < 0.05),and the cardiac function of the Tenascin-C treatment group was further improved(P<0.05).4.The area of infarcted myocardium of the mice in the BMMSC transplantation group was less than that in the control group(P<0.05),and that in the Tenascin-C treatment group was further reduced(P<0.05).5.The concentrations of TNF-?,TGF-?,IL-6 and IL-10 in the BMMSC transplantation group were lower than those in the control group(P <0.05),and the levels of these inflammatory factors in the Tenascin-C treatment group were further reduced(P<0.05).6.BMMSC homing was seen in the infarcted myocardium in the GFP labeled BMMSC transplantation group,and the homing rate of the BMMSC in the Tenascin-C treatment group inreased significantly(P<0.05).Conclusions BMMSC transplantation can improve the cardiac function of AMI mice.Tenascin-C can further improve the cardiac function of AMI mice,with possible mechanism that Tenascin-C can promote BMMSC homing to the infarcted myocardium,has an anti-inflammatory effect,and then exerts the myocardial repair effect in AMI mice. |
PDF Full Text Request