Growth differentiation factor 11 promotes macrophage polarization towards M2 to attenuate myocardial infarction via inhibiting Notch1 signaling pathway

Background:Myocardial infarctions(MI)is a major threat to human health especially in people exposed to cold environment.The polarization of macrophages towards different functional phenotypes(M1 macrophages and M2 macrophages)is closely related to MI repairment.The growth differentiation factor 11(GDF11)has been reported to play a momentous role in inflammatory associated diseases.In this study,we examined the regulatory role of GDF11 in macrophage polarization and elucidated the underlying mechanisms in MI.Methods:In vivo,the mice model of MI was induced by permanent ligation of the left anterior descending coronary artery(LAD),and mice were randomly divided into the sham group,MI group,and MI+GDF11 group.The protective effect of GDF11 on myocardial infarction and its effect on macrophage polarization were verified by echocardiography,triphenyl tetrazolium chloride staining and immunofluorescence staining of heart tissue.In vitro,based on the RAW264.7 cell line,the effect of GDF11 in promoting macrophage polarization toward the M2 type by inhibiting the Notch1 Signaling pathway was validated by qRT-PCR,Western blot,and flow cytometry.Results:We found that GDF11 was significantly downregulated in the cardiac tissue of MI mice.And GDF11 supplementation can improve the cardiac function.Moreover,GDF11 could reduce the proportion of M1 macrophages and increase the accumulation of M2 macrophages in the heart tissue of MI mice.Furthermore,the cardioprotective effect of GDF11 on MI mice was weakened after macrophage clearance.At the cellular level,application of GDF11 could inhibit the expression of M1 macrophage(classically activated macrophage)markers iNOS,interleukin(IL)-1β,and IL-6 in a dose-dependent manner.In contrast,GDF11 significantly increased the level of M2 macrophage markers including IL-10,CD206,arginase 1(Arg1),and vascular endothelial growth factor(VEGF).Interestingly,GDF11 could promote M1 macrophages polarizing to M2 macrophages.At the molecular level,GDF11 significantly down-regulated the Notch1 signaling pathway,the activation of which has been demonstrated to promote M1 polarization in macrophages.Conclusions:GDF11 promoted macrophage polarization towards M2 to attenuate myocardial infarction via inhibiting Notch1 signaling pathway.

Mechanism of Qiliqiangxin capsule on the regulation of IP3Rs/GRP75/VDAC1 gene in myocardial infarction rat heart

Objective:To investigate the regulatory effect of Qiliqiangxin Capsule on mitochondrial Ca^(2+)related genes in rats with myocardial infarction(MI).Methods:The rat model of MI was established by ligation of the left anterior descending coronary artery.After operation,the rats were randomly assigned to the model group,the Qiliqiangxin group and the captopril group;a sham-operated group was also available as a control.After four weeks of treatment,the extent of infarction in rats was observed by gross cardiac structure and the morphological changes of myocardial histopathology were observed by HE staining.Detection of mitochondrial Ca^(2+)transport-related genes such as inositol-1,4,5-trisphosphate receptor 2(IP3R2),glucose regulated protein 75(GRP75),voltage-dependent anion channel 1(VDAC1),and mitofusion 2(Mfn2)and mitochondrial apoptosis-related genes such as B-cell lymphoma-2(Bcl-2)and Bcl-2 related X protein(Bax)mRNA expression changes was measured by RT-PCR in the infarct margins of the heart;Western blot was used to detect changes in Bcl-2,Bax protein expression in myocardial tissue.The rate of apoptosis in cardiac myocardial tissue was detected by TUNEL staining.Results:Compared with the sham group,the anterior left ventricular wall of the model group showed a large area of infarction,and the structure of myocardial tissue was disordered.The mRNA expression level of mitochondrial Ca^(2+)transport-related genes such as IP3R2,GRP75,VDAC1,and Mfn2 were significantly increased(P<0.05,P<0.01);The mRNA and protein expression of Bcl-2,a molecule related to mitochondrial apoptosis,were significantly decreased(P<0.01),while the mRNA and protein expression of Bax were significantly increased(P<0.01);and apoptosis rate was significantly increased(P<0.01).Compared with the model group,the infarct size of cardiac gross specimens in the Qiliqiangxin group and the captopril group was reduced and myocardial fibers were relatively well ordered;The mRNA expression of mitochondrial Ca^(2+)transport-related genes such as IP3R2,GRP75,VDAC1,and Mfn2 were significantly reduced(P<0.01);the mRNA and protein expression of Bcl-2,a molecule related to mitochondrial apoptosis,were increased(P<0.05,P<0.01),and the mRNA and protein expression of Bax were significantly decreased(P<0.05,P<0.01).and apoptosis rate was significantly decreased(P<0.01).Conclusion:Qiliqiangxin Capsule can improve the morphological structure of the heart of rats with MI,and its mechanism is related to regulation of the gene expression of mitochondrial Ca^(2+)transport complex IP3R2/GRP75/VDAC1,thereby inhibiting apoptosis.

Effects of neuregulin-1 on autonomic nervous system remodeling post-myocardial infarction in a rat model

Sympathetic nerve and vagus nerve remodeling play an important part in cardiac function post-myocardial infarction （MI）. Increasing evidence indicates that neuregulin-1 （NRG-1） improves cardiac function following heart failure. Since its impact on cardiac function and neural remodeling post-MI is poorly understood, we aimed to investigate the role of NRG-1 in autonomic nervous system remodeling post-MI. Forty-five Sprague-Dawley rats were equally randomized into three groups： sham （with the left anterior descending coronary artery exposed but without ligation）, MI （left anterior descending coronary artery ligation）, and MI plus NRG-1 （left anterior descending coronary artery ligation followed by intraperitoneal injection of NRG-1 （10 lag/kg, once daily for 7 days））. At 4 weeks after MI, echocardi- ography was used to detect the rat cardiac function by measuring the left ventricular end-systolic inner diameter, left ventricular diastolic diameter, left ventricular end-systolic volume, left ventricular end-diastolic volume, left ventricular ejection fraction, and left ventricular fractional shortening, mRNA and protein expression levels of tyrosine hydroxylase, growth associated protein-43 （neuronal specific pro- tein）, nerve growth factor, choline acetyltransferase （vagus nerve marker）, and vesicular acetylcholine transporter （cardiac vagal nerve fiber marker） in ischemic myocardia were detected by real-time PCR and western blot assay to assess autonomous nervous remodeling. After MI, the rat cardiac function deteriorated significantly, and it was significantly improved after NRG-1 injection. Compared with the MI group, mRNA and protein levels of tyrosine hydroxylase and growth associated protein-43, as well as choline acetyltransferase mRNA level significantly decreased in the MI plus NRG-1 group, while mRNA and protein levels of nerve growth factor and vesicular acetylcholine transporters, as well as choline acetyltransferase protein level slightly decreased. Our results indicate that NRG- 1 can improve cardiac function and regulate sympathetic and vagus nerve remodeling post-MI, thus reaching a new balance of the autonomic nervous system to protect the heart from injury.

Chemokine-like factor 1 (CKLF1) is expressed in myocardial ischemia injury in vivo and in vitro

Introduction:Chemokine-like factor 1(CKLF1)is a chemokine that is overexpressed in several diseases.Our previousfindings revealed a significant increase in CKLF1 expression in the ischemic brain,suggesting its potential as a therapeutic target for ischemic stroke.Methods:In this study,we examined the expression dynamics of CKLF1 in both in vivo and in vitro models of ischemic cardiac injury.Myocardial infarction(MI)was induced in vivo by ligation of the left anterior descending artery(LAD)of the rat heart.The levels of CKLF1,Creatine Kinase MB Isoenzyme(CK-MB),and Lactate dehydrogenase(LDH)in the serum were detected using Enzyme-linked immunosorbent assay(ELISA).The expression of CKLF1 in the infarcted area was detected by immunohistochemistry,immunofluorescence,quantitative PCR(qPCR),and Western blotting(WB).H9C2 and AC16 cardiomyocytes cultured in vitro were subjected to oxygen and glucose deprivation(OGD).LDH was used to detect cell damage,and CKLF1 expression was detected by qPCR and WB.Results:CKLF1 mRNA and protein expression were significantly increased in h9c2 cells at 1.5 h and in AC16 cells at 4 h after OGD.The serum CK-MB in rats increased significantly on thefirst day after infarction,while the LDH concentration increased significantly on the third day after infarction.CKLF1 blood levels significantly increased on thefirst day following MI in rats.CKLF1 expression notably increased in the infarct area on days 1,3,and 7 post-MI.In MI tissue,CKLF1 colocalizes with cardiomyocytes,macrophages,and neutrophils.Conclusion:CKLF1 was substantially expressed during myocardial ischemia injury both in vivo and in vitro and was colocalized with macrophages and neutrophils,indicating that CKLF1 is expected to be a biomarker and a drug target for the treatment of myocardial infarction.

Neuregulin-1 therapy improved cardiac function and reduced ANPmRNA expression in post myocardial infarction rats with cardiac dysfunction

Objective To observe the influence of neuregulin-1 on the cardiac function of post-myocardial infarction rats.Methods Left ventricular MI was created in Sprague-Dawley rats by ligation of the left anterior descending coronary.Six months after the operation,rats were evaluated with echocardiology methods.36 rats that had an infarct area and a EF around 60%were randomized into 3 groups:MI group(n=12)were injected a blank vehicle fluid intravenously for 5 days,after which they continued to be raised on standard food and water for 30 days.MI+NRG group(n=12),received NRG-110μg·kg-^(1) intravenously for 5 days,after which they continued to be raised on standard food and water for 30 days.MI+Capt group(n=12)received captopril orally(dissolved in their drinking water 2g/L)for 30days,after which tap water substituted the solution for 5 days.Final echocardiographic and hemodynamic measurements were made at the end of 1 month of therapy.Total RNA was extracted from frozen left ventricular tissues,and was reverse transcribed into firststrand PCR was performed with primers for BNP、ANP.Results Rats treated with neuregulin had a smaller LVDs(P=0.014),a betterLVEF(P=0.004),and a tendency towards less lung perfusion than untreated rats.Neuregulin decreased the expression of ANP mRNA in the ventricle(P=0.025).Conclusion Neuregulin markedly improved the cardiac function of rats that survived myocardial infarction,and decreased the expression of ANP mRNA in the ventricle.

Dynamic resistance exercise increases skeletal muscle-derived FSTL1 inducing cardiac angiogenesis via DIP2A-Smad2/3 in rats following myocardial infarction

Purpose:The aim of this study was to investigate the potential of dynamic resistance exercise to generate skeletal muscle-derived follistatin like-1(FSTL1),which may induce cardioprotection in rats following myocardial infarction(MI)by inducing angiogenesis.Methods:Male,adult Sprague-Dawley rats were randomly divided into 5 groups(n=12 in each group):sham group(S),sedentary MI group(MI),MI+resistance exercise group(MR),MI+adeno-associated virus(AAV)-FSTL1 injection group(MA),and MI+AAV-FSTL1 injection+resistance exercise group(MAR).The AAV-FSTL1 vector was prepared by molecular biology methods and injected into the anterior tibialis muscle.The MI model was established by ligation of the left anterior descending coronary artery.Rats in the MR and MAR groups underwent 4 weeks of dynamic resistance exercise training using a weighted climbing-up ladder.Heart function was evaluated by hemodynamic measures.Collagen volume fraction of myocardium was observed and analyzed by Masson’s staining.Human umbilical vein vessel endothelial cells culture and recombinant human FSTL1 protein or transforming growth factor-b receptor 1(TGFbR1)inhibitor treatment were used to elucidate the molecular signaling mechanism of FSTL1.Angiogenesis,cell proliferation,and disco interacting protein 2 homolog A(DIP2A)location were observed by immunofluorescence staining.The expression of FSTL1,DIP2A,and the activation of signaling pathways were detected by Western blotting.Angiogenesis of endothelial cells was observed by tubule experiment.One-way analysis of variance and Student’s t test were used for statistical analysis.Results:Resistance exercise stimulated the secretion of skeletal muscle FSTL1,which promoted myocardial angiogenesis,inhibited pathological remodeling,and protected cardiac function in MI rats.Exercise facilitated skeletal muscle FSTL1 to play a role in protecting the heart.Exogenous FSTL1 promoted the human umbilical vein vessel endothelial cells proliferation and up-regulated the expression of DIP2A,while TGFbR1 inhibitor intervention down-regulated the phosphorylation level of Smad2/3 and the expression of vascular endothelial growth factor-A,which was not conducive to angiogenesis.FSTL1 bound to the receptor,DIP2A,to regulate angiogenesis mainly through the Smad2/3 signaling pathway.FSTL1-DIP2A directly activated Smad2/3 and was not affected by TGFbR1.Conclusion:Dynamic resistance exercise stimulates the expression of skeletal muscle-derived FSTL1,which could supplement the insufficiency of cardiac FSTL1 and promote cardiac rehabilitation through the DIP2A-Smad2/3 signaling pathway in MI rats.

Comparison of plasma microRNA-1 and cardiac troponin T in early diagnosis of patients with acute myocardial infarction

BACKGROUND:Early reperfusion can effectively treat acute myocardial infarction(AMI) and reduce the mortality signif icantly. This study aimed to compare the role of plasma microRNA-1(miR-1) and cardiac troponin T(cTnT) in early diagnosis of AMI patients.METHODS:From May 2011 to May 2012,plasma samples were collected from 56 AMI patients and 28 non-AMI controls. The expression of plasma miR-1 was measured by quantitative reverse transcription-polymerase chain reaction(qRT-PCR),and the level of plasma cTnT was measured using electrochemiluminescence-based methods on an Elecsys 2010 Immunoassay Analyzer. SPSS 16.0 was used for the statistical analysis of the results. Data were expressed as mean±standard deviation unless otherwise described. The differences about clinical characteristics between the AMI patients and controls were tested using Student's t test or Fisher's exact test. The Mann-Whitney U test was conducted to compare the expression of microRNAs between the AMI patients and controls. MicroRNAs expression between different intervals of the AMI patients was compared using Wilcoxon's signed-rank test. The receiver operating characteristic(ROC) curve was established to discriminate the AMI patients from the controls.RESULTS:In the present study,the expression of plasma miR-1 was signifi cantly increased in the AMI patients compared with the healthy controls(P<0.01). The plasma miR-1 in the AMI patients decreased to the normal level at 14 days(P>0.05). The expression of plasma miR-1 was not related to the clinical characteristics of the study population(P>0.05). ROC curve analyses demonstrated that miR-1 was specifi c and sensitive for the early diagnosis of AMI,but not superior to cTnT.CONCLUSION:Plasma miR-1 could be used in the early diagnosis of AMI,but it is similar to cTnT.

Inhibition of TGF-β1 by eNOS gene transfer provides cardiac protection after myocardial infarction

Objective： Endothelial nitric oxide synthase （eNOS） and nitric oxide （NO） have been implicated in protection against myocardial ischemia injury. This study was designed to explore a new method of therapy for myocardial injury by eNOS gene transfection. Methods： A rat model of myocardial infarction （MI） was established by left anterior descending （LAD） coronary artery ligation, eNOS gene in an adenovirus vector was delivered locally into the rat heart and hemodynamic parameters were examined after 3 weeks, Matrix metalloproteinase-2 and 9 （MMP-2, MMP-9） mRNA were measured by reverse transcription polymerase chain reaction （RT-PCR）, and the protein levels of eNOS, caspase-3, and transforming grouth factor 131 （TGF-131） were determined by western blot assay. Results： eNOS gene transfer significantly reduced cardiomyocyte apoptosis and improved cardiac function. In addition, eNOS significantly reduced the mRNA levels of MMP-2 and MMP-9. In the eNOS gene transfected group, the activation of caspase-3 and TGF-β1 were decreased. However, the protection was reversed by administration of the NOS inhibitor, N（o））-nitro-l-arginine methyl ester （L-NAME）. Conclusion： These results demonstrate that the eNOS provides cardiac protection after myocardial infarction injury through inhibition of cardiac apoptosis and collagen deposition, and suppression of TGF-β1.

Association of G+1688A Polymorphism of Platelet Endothelial Cell Adhesion Molecule-1 Gene with Myocardial Infarction in the Chinese Han Population

In order to investigate the association of G＋1688A （Ser563Asn） polymorphism of platelet endothelial cell adhesion molecule-1 （PECAM-1） gene with myocardial infarction （MI） in the Chinese Han population, the G＋1688A polymorphism in PECAM-1 gene was detected by polymerase chain reaction-restriction fragment-length polymorphism （PCR-RFLP） method among 502 subjects, including 218 patients with MI and 284 controls. The results showed that there was significant difference in AA frequencies of genotype G＋1688A polymorphism between case and control groups （39% vs 24%, P〈0.001）. A similar trend was observed on the allele frequencies （A/G： 62% vs 49%, P〈0.001）. Among the subjects with high serum total cholesterol level or high systolic blood pressure level, the variant AA genotype was associated with high risk of MI （adjusted OR, 2.13; 95% CI, 1.08 -4.41 and adjusted OR, 2.53; 95%CI, 1.63-3.63）. The single nucleotide polymorphism （SNP） at position ＋1688 in the exon 8 of PECAM-1 gene was associated with MI and the allele A might be a risk factor for MI in the Chinese Han population.

Reactive protein, plasminogen activator inhibitor type-1 （PAI-1） levels, PAI-1 promoter 4G/5G polymorphism and acute myocardial infarction

Objective To investigate the relationship between CRP, plasminogen activator inhibitor type 1 （PAI-1） levels, PAI-1 gene promoter 4G/5G polymorphism and the type of acute myocardial infarction （ST elevation myocardial infarction, STEMI vs the non-ST elevation Myocardial infarction, NSTEMI）. Methods One hundred seventy-six consecutive patients with AMI were included for the study, of whom 60 had STEMI and 56 had NSTEMI, and 60 adults without cardiovascular and cerebrovascular disease were selected as controls. Blood samples were obtained from patients within 6 h of AMI and the plasma PAI-1, CRP, and the gene polymorphism were measured. Results Plasma levels of PAI- 1 and CRP were higher in AMI groups, compared those in the control group, and plasma levels of PAI-1 were significantly higher in patients with STEMI compared to those with NSTEMI （80.12ng/ml VS.73.01ng/ml, P 〈0.01）, while CRP levels were not significantly different between patient with STEMI and NSTEMI （3.87 ± 0.79 mg/ml VS.4.01 ±0.69mg/ml, P〉0.05）. PAI-1 levels presented a significant correlation with CRP levels in the NSTEMI subjects. However, PAI-1 and CRP levels could explain the lack of a significant relationship between them in control and STEMI subjects.The frequencies of 4G/4G genotype in the AMI group were higher than those in the control group and higher in patient with STEMI than in patient with NSTEMI. Plasma levels of PAI-1 in subjects with 4G/4G genotype were significantly increased as compared to those in subjects with 4G/5G and 5G/5G genotype. Conclusions Plasma PAI-1 levels were associated with different myocardial infarction type, and PAI-1 promoter 4G/5G polymorphisms and CRP may be related to plasma PAI-1 levels

Monocyte chemotactic protein 1 increases homing of mesenchymal stem cell to injured myocardium and neovascularization following myocardial infarction

Objective：To investigate the effect of MCP-1 on mesenchymal stem cells（MSCs） homing to injured myocardium in a rat myocardial infarction（MI） model. Methods：Rat myocardial infarction model was established by permanent left anterior descending branch ligation. Mesenchymal stem cells from donor rats were cultured in IMDM and labeled with BrdU. The Rats were divided into two groups. Monocyte chemotactic protein I（MCP-1） expression were measured by in situ hybridization and immunohistochemistry in the sham operated or infarcted hearts at 1, 2, 4, 7, 14 and 28 days post operation in MCP-1 detection group. The rats were injected with MCP-1, anti-MCP-1 antibody or saline 4 days after myocardial infarction in intervention group. Then, a total of 5 × 10^6 cells in 2.5 ml of PBS were injected through the tail vein. The number of the labeled MSCs in the infarcted hearts was counted 3 days post injection. Cardiac function and blood vessel density were assessed 28 days post injection. Results：Self-generating MCP-1 expression was increased at the first day, peaked at the 7^th day and decreased thereafter post MI and remained unchanged in sham operated hearts. The MSCs enrichment in the host hearts were more abundant in the MI groups than that in the non-MI group（P= 0.000）, the MSCs enrichment in the host hearts were more abundant in the MCP-1 injected group than that in the anti-MCP-1 antibody and saline injected groups （P = 0.000）. Cardiac function was improved more in MCP-1 injected group than anti-MCP-1 antibody and saline injected groups（P= 0.000）. Neovascularization in MCP-1 injected group significantly increased compared with that of other groups（P = 0.000）. Conclusion： Myocardial MCP-1 expression was increased only in the early phase post MI. MCP-1 may enhance MSCs homing to the injured heart and improve cardiac function by promoting neovascularization.

Lack of Association of Common Polymorphism of LRP1 Gene with Myocardial Infarction in a Chinese Han Population

This study examined the association of a common polymorphic allele（25G） of the low-density lipoprotein receptor-related protein1（LRP1） gene with myocardial infarction（MI）.The genotypes of LRP1 25CG（rs35282763） were determined in 347 MI patients and 347 age-and sex-frequency-matched controls from an unrelated Chinese Han population.Factor Ⅷ（FⅧ） levels were measured in the MI patients and controls by chromogenic assay and enzyme-linked immunosor-bent assay（ELISA）.The results showed that LRP1 25CG（rs35282763） genotype distribution did not differ significantly between patients（n=206 for 25CC,n=122 for 25CG） and controls（n=191 for 25CC,n=126 for 25CG;P0.05）.The 25G allele was not associated with a reduced risk of MI（P0.05）.Further stratifications for age,sex,and other cardiovascular risk factors did not affect the negative findings.It was concluded that the presence of the G allele at the 25CG（rs35282763） polymorphism of the LRP1 is not associated with a reduced risk of MI,and genotyping for LRP1 25CG（rs35282763） polymor-phism is not useful in assessing the individual risk of MI.

Stromelysin-1 Gene Promoter 5A/6A Polymorphism and Plasma C-Reactive Protein in Patients with Coronary Artery Disease and Myocardial Infarction

Objective: To study the associations of stromelysin-1 (MMP3) gene 5A/6A polymorphism with plasma high-sensitivity C-reactive protein (hs-CRP) level in coronary artery disease (CAD) and myocardial infarction (MI). Methods: The MMP3 5A/6A genotypes and plasma hs-CRP levels were determined in 405 non-CAD subjects and 395 angiography-documented CAD patients, 157 with MI and 238 with non-MI. Results: The percentage of the 5A/5A genotype was significantly (p < 0.001) greater in CAD than non-CAD subjects and in MI than non-MI patients. Plasma hs-CRP level of the 5A/5A genotype was significantly (p < 0.05) higher than that of the 6A/6A genotype in CAD and MI but not in non-MI patients. On logistic regression analysis, the odds ratio of the 5A/5A genotype for CAD was 2.11 (95% CI, 1.15 - 3.88, p < 0.05) and for MI was 3.05 (95% CI, 1.54 - 6.04, p < 0.005). Conclusions: This study showed a correlation of the 5A/5A genotype of MMP3 promoter with higher plasma hs-CRP level in CAD patients with MI.

Recent advances in the diagnosis and treatment of acute myocardial infarction

The Third Universal Definition of Myocardial Infarction(MI) requires cardiac myocyte necrosis with an increase and/or a decrease in a patient's plasma of cardiac troponin(cT n) with at least one cT n measurement greater than the 99 th percentile of the upper normal reference limit during:(1) symptoms of myocardialischemia;(2) new significant electrocardiogram(ECG) ST-segment/T-wave changes or left bundle branch block;(3) the development of pathological ECG Q waves;(4) new loss of viable myocardium or regional wall motion abnormality identified by an imaging procedure; or(5) identification of intracoronary thrombus by angiography or autopsy.Myocardial infarction,when diagnosed,is now classified into five types.Detection of a rise and a fall of troponin are essential to the diagnosis of acute MI.However,high sensitivity troponin assays can increase the sensitivity but decrease the specificity of MI diagnosis.The ECG remains a cornerstone in the diagnosis of MI and should be frequently repeated,especially if the initial ECG is not diagnostic of MI.There have been significant advances in adjunctive pharmacotherapy,procedural techniques and stent technology in the treatment of patients with MIs.The routine use of antiplatelet agents such as clopidogrel,prasugrel or ticagrelor,in addition to aspirin,reduces patient morbidity and mortality.Percutaneous coronary intervention(PCI) in a timely manner is the primary treatment of patients with acute ST segment elevation MI.Drug eluting coronary stents are safe and beneficial with primary coronary intervention.Treatment with direct thrombin inhibitors during PCI is non-inferior to unfractionated heparin and glycoprotein Ⅱb/Ⅲa receptor antagonists and is associated with a significant reduction in bleeding.The intra-coronary use of a glycoprotein Ⅱb/Ⅲa antagonist can reduce infarct size.Pre- and post-conditioning techniques can provide additional cardioprotection.However,the incidence and mortality due to MI continues to be high despite all these recent advances.The initial ten year experience with autologous human bone marrow mononuclear cells(BMCs) in patients with MI showed modest but significant increases in left ventricular(LV) ejection fraction,decreases in LV endsystolic volume and reductions in MI size.These studies established that the intramyocardial or intracoronary administration of stem cells is safe.However,many of these studies consisted of small numbers of patients who were not randomized to BMCs or placebo.The recent LateT ime,Time,and Swiss Multicenter Trials in patientswith MI did not demonstrate significant improvement in patient LV ejection fraction with BMCs in comparison with placebo.Possible explanations include the early use of PCI in these patients,heterogeneous BMC populations which died prematurely from patients with chronic ischemic disease,red blood cell contamination which decreases BMC renewal,and heparin which decreases BMC migration.In contrast,cardiac stem cells from the right atrial appendage and ventricular septum and apex in the SCIPIO and CADUCEUS Trials appear to reduce patient MI size and increase viable myocardium.Additional clinical studies with cardiac stem cells are in progress.

The expression of oxidative stress genes related to myocardial ischemia reperfusion injury in patients with ST-elevation myocardial infarction

BACKGROUND:We aimed to investigate the gene expression of myocardial ischemia/reperfusion injury(MIRI)in patients with acute ST-elevation myocardial infarction(STEMI)using stress and toxicity pathway gene chip technology and try to determine the underlying mechanism.METHODS:The mononuclear cells were separated by ficoll centrifugation,and plasma total antioxidant capacity(T-AOC)was determined by the ferric reducing ability of plasma(FRAP)assay.The expression of toxic oxidative stress genes was determined and verified by oligo gene chip and quantitative real-time polymerase chain reaction(qRT-PCR).Additionally,gene ontology(GO)enrichment analysis was performed on DAVID website to analyze the potential mechanism further.RESULTS:The total numbers of white blood cells(WBC)and neutrophils(N)in the peripheral blood of STEMI patients(the AMI group)were significantly higher than those in the control group(WBC:11.67±4.85×10^(9)/L vs.6.41±0.72×10^(9)/L,P<0.05;N:9.27±4.75×10^(9)/L vs.3.89±0.81×10^(9)/L,P<0.05),and WBCs were significantly associated with creatine kinase-myocardial band(CK-MB)on the first day(Y=8.945+0.018X,P<0.05).In addition,the T-AOC was significantly lower in the AMI group comparing to the control group(12.80±1.79 U/mL vs.20.48±2.55 U/mL,P<0.05).According to the gene analysis,eight up-regulated differentially expressed genes(DEGs)included GADD45A,PRDX2,HSPD1,DNAJB1,DNAJB2,RAD50,TNFSF6,and TRADD.Four down-regulated DEGs contained CCNG1,CAT,CYP1A1,and ATM.TNFSF6 and CYP1A1 were detected by polymerase chain reaction(PCR)to verify the expression at different time points,and the results showed that TNFSF6 was up-regulated and CYP1A1 was down-regulated as the total expression.GO and kyoto encyclopedia of genes and genomes(KEGG)enrichment analysis suggested that the oxidative stress genes mediate MIRI via various ways such as unfolded protein response(UPR)and apoptosis.CONCLUSIONS:WBCs,especially neutrophils,were the critical cells that mediating reperfusion injury.MIRI was regulated by various genes,including oxidative metabolic stress,heat shock,DNA damage and repair,and apoptosis-related genes.The underlying pathway may be associated with UPR and apoptosis,which may be the novel therapeutic target.

Effect of exercise training on left ventricular remodeling in patients with myocardial infarction and possible mechanisms

BACKGROUND A growing amount of evidence provides support for the hypothesis that acute myocardial infarction(AMI)patients should go through cardiopulmonary exercise testing(CPET)about 3-5 d after AMI is diagnosed,make reasonable exercising prescription,and conduct exercise training under guidance.AIM To investigate the effect of exercise training(ET)on left ventricular systolic function and left ventricular remodeling(LVRM)and to study the possible mechanisms of LVRM by the changes of matrix metallopeptidase 9(MMP-9)and tissue inhibitor of metalloproteinases 1(TIMP-1)in patients with acute STsegment elevation myocardial infarction(STEMI).METHODS Sixty patients with first STEMI undergoing direct percutaneous coronary intervention from February 2008 to October 2008 were randomly assigned to an exercise group(n=30)and a control group(n=30).The levels of MMP-9 and TIMP-1 were measured in all patients at 1 d,10-14 d,30 d,and 6 mo after admission.Two-dimensional echocardiography and cardiopulmonary exercise testing were done in patients at 10-14 d and 6 mo after admission.RESULTS There was no significant difference in CPET at baseline between the exercise group and the control group.At 6 mo,the time of exercise,peak and anaerobic threshold values of O2 uptake,and metabolic equivalents increased in both groups,but markedly increased in the exercise group.At baseline,there were no significant differences in left ventricular ejection fraction(LVEF)between the two groups.At 6 mo,LVEF increased in the exercise group,but not in the control group.At 6 mo,the percentage of patients with positive result of LVRM was 26.6%in the exercise group and 52.6%in the control group(P<0.05).The levels of plasma MMP-9 and TIMP-1 and the ratio of MMP-9 to TIMP-1 in both groups had no significant difference at 1 d and 10-14 d after AMI,but at 30 d and 6 mo,the levels of plasma MMP-9 and TIMP-1 in the exercise group were significantly lower than those in the control group;the ratio of MMP-9 to TIMP-1 in the exercise group was significantly higher than that in the control group.CONCLUSION ET under supervision based on home condition in early and recovery stage of AMI can improve exercise cardiopulmonary function and prevent the LVRM.Therefore,it may reduce unfavorable remodeling response by decreasing the levels of plasma MMP-9 and TIMP-1 and adjusting the ratio of MMP-9 to TIMP-1 hereafter.

Effects of glucagon-like peptide 1 analogs in combination with insulin on myocardial infarct size in rats with type 2 diabetes mellitus

AIM To evaluate the effects of glucagon-like peptide-1 analogs(GLP-1 a) combined with insulin on myocardial ischemiareperfusion injury in diabetic rats.METHODS Type 2 diabetes mellitus(T2 DM) was induced in maleWistar rats with streptozotocin(65 mg/kg) and verified using an oral glucose tolerance test. After anesthesia, the left coronary artery was occluded for 40 min followed by 80 min reperfusion. Blood glucose level was measured during surgery. Rats were randomized into six groups as follows:(1) control rats;(2) insulin(0.1 U/kg) treated rats prior to ischemia;(3) insulin(0.1 U/kg) treated rats at reperfusion;(4) GLP-1 a(140 mg/kg) treated rats prior to ischemia;(5) GLP-1 a(140 mg/kg) treated rats at reperfusion; and(6) rats treated with GLP-1 a(140 mg/kg) prior to ischemia plus insulin(0.1 U/kg) at reperfusion. Myocardial area at risk and infarct size was measured planimetrically using Evans blue and triphenyltetrazolium chloride staining, respectively.RESULTS There was no significant difference in the myocardial area at risk among groups. Insulin treatment before ischemia resulted in a significant increase in infarct size(34.7% ± 3.4% vs 18.6% ± 3.1% in the control rats, P < 0.05). Post-ischemic administration of insulin or GLP-1 a had no effect on infarct size. However, pre-ischemic administration of GLP-1 a reduced infarct size to 12% ± 2.2%(P < 0.05). The maximal infarct size reduction was observed in the group treated with GLP-1 a prior to ischemia and insulin at reperfusion(8% ± 1.6%, P < 0.05 vs the control and GLP-1 a alone treated groups).CONCLUSION GLP-1 a pre-administration results in myocardial infarct size reduction in rats with T2 DM. These effects are maximal in rats treated with GLP-1 a pre-ischemia plus insulin at reperfusion.

Protective Effect of Catalpol on Myocardium in Rats with Isoprenaline-Induced Myocardial Infarcts via Angiogenesis through Endothelial Progenitor Cells and Notch1 Signaling Pathway

Protective effect of catalpol on myocardium was studied in relation to endothelial progenitor cells, Notch1 signaling pathway and angiogenesis in rats with isoprenaline (INN)-induced acute myocardial infarcts. To analyze the pathological status and impact of catalpol on the rats, 3 weeks after intragastric gavage, the animals were verified for myocardial infarcts with electrocardiogram and measured for enzyme activity of lactate dehydrogenase (LDH), malondialdehyde (MDA), creatine kinase (CK) and superoxide dismutase (SOD) in myocardium, and further analyzed using HE and TTC staining, as well as visual examination of infarct area. Flow cytometry study of endothelial progenitor cells (EPCs) indicated that the EPCs were mobilized during infarction. The roles of Notch1 signaling pathway in angiogenesis of the infracted animals were studied using immunohistochemistry analysis of RBPjκ and Western blot analysis of Notch1 and Jagged1. Our results obtained from the rats treated with catalpol, positive drug and control showed that catalpol could protect rats from infarction probably by mobilization of EPCs and activation of Notch1 signaling pathway.

Isometric exercise promotes arteriogenesis in rats after myocardial infarction

Isometric exercise(IE)is a promising intervention of noninvasive revascularization in patients with acute myocardial infarction(AMI).This study aimed to investigate the impact and mechanisms of IE training on arteriogenesis in AMI.Male Sprague-Dawley rats were randomly assigned into the sham-operation group(SO),myocardial infarction(MI)group,and 13 IE subgroups treated according to training intensity,frequency,duration,or monocyte chemoattractant protein-1(MCP-1),or/and fibroblast growth factor-2(FGF-2)inhibitors for eight weeks.Our results demonstrated that the IE group achieved superior improvement compared with the MI group in terms of left ventricular ejection fraction(LVEF),myocardial infarction size(MIS),arterial density(AD),monocytes(MNCs),smooth muscle cells(SMCs),endothelial cells(ECs),relative collateral blood flow(RCBF),MCP-1,and FGF-2 at the endpoint.Positive correlations between MCP-1 and MNCs,MNCs and FGF-2,FGF-2 and SMCs,SMCs and AD,as well as AD and RCBF were observed.This study demonstrated that with MI of 100%load 20 times daily for eight weeks,the arteriogenesis was improved,which may be attributed to the recruitment of MNCs and SMCs in remote ischemic myocardium caused by increases in MCP-1 and FGF-2 expression.

Study on gene regulation mechanism of Qiliqiangxin capsule on myocardial fibrosis in myocardial infarction rats

Objective:To investigate the effect and possible mechanism of Qiliqiangxin capsule on myocardial fibrosis in rats with myocardial infarction(MI).Methods:The rat model of myocardial infarction was established by ligation of anterior descending branch of left coronary artery.The rats were randomly divided into model group,Qiliqiangxin capsule group,captopril group after operation.Rats that without ligation were set as parallel control group,namely,the sham group.Cardiac pathology was observed by hematoxylin eosin(HE)staining after 4 weeks of treatment.Masson staining was used to observe myocardial fibrosis and calculate collagen volume fraction(CVF).The miR-133a and expression levels of transforming growth factor β1(TGF-β1),Smad 2,Smad 3,type Ⅰ collagen(col-Ⅰ),type Ⅲ collagen(col-Ⅲ)mRNA were examined by Real-time PCR.Results:Compared with the sham group,myocardial cells in model group were disordered,CVF was significantly increased(P<0.01),the expression levels of col-Ⅰ,col-ⅢmRNA were increased(P<0.01);besides,the expression level of miR-133a was significantly decreased(P<0.01),the expression levels of TGF-β1,Smad 2 and Smad 3 mRNA were increased(P<0.05,P<0.01).Compared with the model group,the arrangement of myocardial cells in Qiliqiangxin capsule group and captopril group were orderly and CVF was significantly decreased(P<0.05);the expression level of miR-133a was increased(P<0.05,P<0.01);the expression levels of TGF-β1,Smad 2 and Smad 3 mRNA were significantly decreased(P<0.01).Conclusion:Qiliqiangxin capsule can improve myocardial infarction rat myocardial tissue fibrosis,its mechanism may be in related with the regulation on miR-133a/TGF-β1/Smads signal pathway at the genetic level.