Induction Of Acute Myocardial Infarction Research Articles

Cardioprotective effects of Musanga cecropioides Welw. Ex Benth extracts on isoproterenol-induced acute myocardial infarction in Wistar rats.

Background of the study: Acute myocardial infarction (AMI) is a prominent etiology of heart failure-related death worldwide. Musanga cecropioides Welw. Ex Benth bark water extract is used by the Yoruba tribe in Nigeria for the treatment of several metabolic diseases, inflammatory diseases, wounds, coughs, and toothaches. Aim: This work evaluates the cardioprotective effects of M. cecropioides water extract on isoproterenol (ISO)-induced AMI in Wistar rats. Methodology: ISO (100 mg/kg, subcutaneous (s.c.)) was used to induce AMI in rats. Thirty rats (n = 5) were pretreated orally for seven days with normal saline (1.0 ml/kg/day, no-AMI control), normal saline + ISO (1.0 ml/kg/day + 100 mg/kg AMI, control), normal saline + M. cecropioides water extract (1.0 ml/kg/day + 500 mg/kg/day, non-AMI group), M. cecropioides water extract 500 and 1000 mg/kg/day, and captopril (5 mg/kg/po/day) before induction of AMI on the eighth and ninth days. Electrocardiographic changes, lipid peroxidation, biochemical enzyme profile, hematological, and histopathological changes were determined. Results: ISO significantly increased AST, ALT, lipid 15 profile, and oxidative stress marker (MDA). In addition, it caused ST segment elevation, increased heart rate, R-R interval, and degenerative changes in cardiac tissues. Pretreatment with M. cecropioides water extract (500 and 1000 mg/kg) significantly suppressed the biochemical enzyme profile and lipid peroxidation. It also significantly improved changes in histopathological and electrocardiographic imaging of the myocardium. Conclusion: The outcome of this work shows evidence that M. cecropioides water extract may have cardioprotective effects on AMI in rats.

Protectin D1 Alleviates Myocardial Ischemia/Reperfusion Injury by Regulating PI3K/AKT Signaling Pathway.

Myocardial ischemia/reperfusion (I/R) injury after the onset of acute myocardial infarction (AMI) can be life-threatening, and there is no effective strategy for therapeutic intervention. Here, we studied the potential of protectin D1 in protecting from I/R-induced cardiac damages and investigated the underlying mechanisms. An in vivo rat model of I/R after AMI induction was established through the ligation of the left anterior descending (LAD) artery to assess the cardiac functions and evaluate the protective effect of protectin D1. Protectin D1 protected against I/R-induced oxidative stress and inflammation in the rat model, improved the cardiac function, and reduced the infarct size in myocardial tissues. The beneficial effect of protectin D1 was associated with the up-regulation of miRNA-210 and the effects on PI3K/AKT signaling and HIF-1α expression. Together, our data suggest that protectin D1 could serve as a potential cardioprotective agent against I/R-associated cardiac defects.

Histopathological Evaluation of Ameliorated Effect of Citric Acid on Infarcted Myocardium

The estimated disease burden of ischemic heart disease in Pakistan is in millions and discovery of cardioprotective agents of organic origin has great importance to decrease the financial burden on society. Objective: The study was designed to analyze and grade histopathological changes in experimental model of myocardial infarction. Study Design: This was an experimental randomized controlled trial. Place and Duration: The study was organized at King Edward Medical University and University of Veterinary and Animal Sciences, Lahore for a period of 180 days. Methodology: During initial 14 days, cont-group and Isopro-group were treated with 1 ml normal saline, while Citric-250 and Citric-500-group were treated with citric acid at 250 mg and 500 mg per-kg-body-weight respectively. Isoproterenol (85mg per-kg-body-weight) was injected subcutaneously for induction of acute myocardial infarction in all rabbits except for cont-group. Histopathological analysis was done, serum-C.K-M.B (creatine-kinase-M.B), serum-L.D.H (lactate-dehydrogenase) and cTn-I (cardiac.troponin-I) were recorded at the end of experiment. S.P.S.S software (statistical package for social sciences) was applied for statistically analyzed of data. Results: Isopro-group showed augmented odema, infiltration and necrosis in myocardium on histopathological study along with elevated level of C.K-M.B, L.D.H and cTn-I as compare to other group. Citric-250 and citric-500-group showed significant recovery with reduced odema, infiltration and necrosis in myocardium on histopathological analysis along with lesser values of C.K-M.B, L.D.H and cTn-I as compare to Isopro-group. Practical Implication: Consumption of citric acid protects from acute myocardial infarction. Conclusion: It is concluded that citric acid possesses strong cardioprotective potential. It reduces the myocardial injury during infarction in term of edema, infiltration and necrosis that help myocardium to survive during ischemic condition. Keywords: Citric acid, Isoproterenol, Formalin, cTn-I, Infiltration and Myocardial Infarction.

S1P lyase inhibition improves post-ischemic cardiac remodeling independently of infarct size via S1P receptor 1

Abstract Background Revascularization of the infarct vessel is the golden standard in acute myocardial infarction (AMI). Even in Western countries, more than ten percent of AMI patients are so-called “latecomers” and it is controversial if revascularization of the infarct vessel is beneficial in these patients. Current guidelines even discourage revascularization of the infarcted artery if symptom onset was >48 hours and the patient is asymptomatic. These patients are at high risk for cardiovascular events and heart failure with reduced ejection fraction (HFrEF). HFrEF has an enormous socio-economic impact, high morbidity, and mortality. Purpose Therapeutic options targeting post-ischemic cardiac remodeling are sparse. The bioactive sphingolipid sphingosine-1-phosphate (S1P) reduces ischemia/reperfusion injury when administered in advance. However, its impact on post-ischemic remodeling independently of its infarct size (IS)-reducing effect is yet unknown. Methods Acute myocardial infarction (AMI) in mice was induced by permanent ligation of the left anterior descending artery (LAD). C57Bl/6J were treated with the S1P lyase inhibitor 4-deoxypyridoxine (DOP) starting seven days prior to AMI to increase endogenous S1P concentrations. Cardiac function and myocardial healing were assessed by cardiovascular magnetic resonance imaging (cMRI), histomorphology and gene expression analysis. DOP effects were investigated in cardiomyocyte-specific S1P receptor 1 deficient (S1PR1 Cardio Cre+ and Cre− control) mice, and S1P concentrations measured by LC-MS/MS. Results S1P concentrations in plasma before induction of AMI were increased fourfold by DOP (Control 0.97±0.09μM [n=6] vs. DOP 3,80±0,09μM [n=6]). Scar size determined by MRI, as well as ejection fraction (EF), did not differ 24 h post AMI. In contrast, after 21 days, there was a clear difference between the two groups (scar size vehicle: 19.3±6.2% vs. DOP 13.4±5.7%; EF: Vehicle: 26.4±8.7% vs. DOP 38.2±11.8%). In addition, in the remote area 21 days post AMI in the DOP-treated animals, a reduced gene expression of brain natriuretic peptide, atrial natriuretic peptide and collagen 1a2. Finally, cardiomyocyte diameter in the remote myocardium was 21% smaller in DOP-treated (Vehicle: 21.95±1.59μm vs. DOP 17.35±0.77μm). The benefit of DOP-treatment was abolished in cardiomyocyte-specific S1PR1-deficient mice. Conclusion S1P improves cardiac function and myocardial healing post AMI independently of initial infarct size via S1PR1. Hence, in addition to its beneficial effects on I/R injury, S1PR1 may be a promising target in post-infarction myocardial remodeling as adjunctive therapy to revascularization and in patients who are not eligible for standard interventional procedures. Funding Acknowledgement Type of funding sources: None.

Perivascular nerve fibres are increased in the epicardium while perivascular adipose tissue is decreased in the myocardium in patients with acute myocardial infarction

Abstract Background Vasospasm is an important etiological factor in the induction of acute myocardial infarction (AMI). PeriVascular Nerve Fibres (PVNF) and PeriVascular Adipose Tissue (PVAT) play an important role in vasoregulation, although detailed information of their role in the heart is missing in AMI patients. In the present study we have analysed PVNF and PVAT in deceased AMI patients. Methods Sections of epicardial coronary arteries were obtained at autopsy from AMI patients (N=16) and controls without heart disease (N=7). Infarct age was between 3 and 6 hours old. Stenosis of epicardial coronary arteries was quantified in a HE stained slide. To analyse the intramyocardial vasculature samples were taken from the left ventricle of the heart (in AMI patients the infarcted area). Nerve fibres were stained using a specific S100 antibody. Putative activation of these nerves was stained using a specific antibody against neuropeptide Y (NPY). S100+ and NPY+ nerve fibres were quantified by light microscopy and were then calculated per square mm of the adventitia surface areas. PVAT was quantified using an Elastica Von Gieson (EvG) staining. Results Stenosis did not correlate with PVNF. AMI patients had a significant increase in PVNF in the epicardium but not in the myocardium. NPY was non-significantly increased in PVNF in the epicardium and myocardium in AMI patients compared with controls. PVAT was significantly decreased in AMI patients compared with controls. Conclusion The increase in PVNF in the epicardium and the decrease of PVAT in the myocardium suggest that they might play a role in AMI induction, independent of the atherosclerotic changed epicardial coronary arteries. Funding Acknowledgement Type of funding sources: None.

Role of tissue resident VSIG4+ macrophages in cardiac remodeling after acute myocardial infarction in mice

Adaptive and innate immune cells have been shown to govern cardiac injury and remodeling following acute myocardial infarction (AMI). A detailed understanding of the interactions between inflammation and the structural and functional alterations of the infarcted heart could pave the way for the development of innovative therapeutic strategies. In the infarcted heart, macrophages constitute a heterogeneous population including monocyte-derived macrophages (MDM) emerging from splenic and medullary reservoirs and tissue-resident macrophages (TRM). MDM rather exert pro-inflammatory deleterious effects whereas TRM are more likely to perform anti-inflammatory protective functions in the infarcted heart. Using single cell RNA sequencing, we revealed that VSIG4 (B7 family-related protein V-set and Ig domain-containing 4) characterized a specific subset of TRM in the cardiac tissue. In the present work, we therefore aim to evaluate the role of VSIG4 + TRM after AMI. Acute MI was induced by permanent ligation of the left anterior descending coronary artery in mice. Cardiac function and remodeling were assessed using echocardiography and immunohistochemistry. Vsig4 depletion impaired cardiac function and promoted adverse cardiac remodeling after experimental AMI in mice. WT mice, transplanted with bone marrow (BM) derived cells isolated from Vsig4-deficient mice (Vsig4-/-) or WT mice, exhibited comparable cardiac function and remodeling after AMI. Conversely, Vsig4 deficient mice transplanted with WT BM-derived cells, displayed worse cardiac function and adverse ventricular remodeling after AMI, when compared to WT mice re-supplemented with WT BM-derived cells. Moreover, FACS-sorted Vsig4+ macrophages injected into infarcted hearts 2 weeks post-AMI, improved cardiac function in both WT and Vsig4-/- mice, supporting the beneficial role of VSIG4+ TRM in the context of AMI. We have also demonstrated that IL4 and IL13, through IL4 receptor alpha and IL13 receptor alpha1, fostered Vsig4 expression in peritoneal macrophages (PEM), a prototypical example of TRM. Meanwhile, IL4 and IL13 elicited the release of CCL3, CCL4 and CCL5, chemokine ligands of CCR5, in cultured WT PEM but not in Vsig4-deficient PEM. Moreover, induction of AMI in Vsig4-/- mice hampered the number of CCR5+ regulatory T lymphocytes in infarcted hearts. VSIG4+ TRM are key regulators of cardiac healing after AMI likely through their ability to foster the infiltration of anti-inflammatory regulatory T cells in the infarcted heart.

Comparative Study Among Three Different Models for Induction of Acute Myocardial Infarction in Rats

Abstract Aim Laboratory study of Acute Myocardial Infarction (AMI) has become of great importance for further investigations about prevention, diagnosis and treatment of the increasing number of patients worldwide. In this study, we are seeking the best experimental AMI model by comparing three methods by which AMI can be experimentally induced in rats to illuminate the most reliable model to use in further studies. Methods and Results Experimentally, AMI can be produced by either drug induced methods or surgical methods. Here, we compared two drug induced methods (isoproterenol and doxorubicin) and a surgical model to find out which method is best simulating human AMI. 50 male sprague dowley rats were put into 5 groups, each contained 10 rats as follows. Surgical group in which the proximal left anterior descending coronary artery (LADCA) was dissected and ligated. Isoproterenol group in which Isoproterenol (300 gm/kg) was injected in ten rats subcutaneously on 2 doses a day apart. Doxorubicin group in which doxorubicin (2.5 mg/kg) was given intraperitonially every other day for total cumulative dose of 15 mg/kg. Control group where rats received only 2 ml of saline intraperitonially or subcutaneously. Sham group where rats underwent a similar surgery, but without LADAC ligation. After the induction, the biochemical parameter (serum Troponin I) at 12, 24, 36, 48 and 72 hours and histopathological changes (using hematoxylin, eosin and Mallory's trichrome stains) in all groups on days 1, 7, 14 and 21 were recorded. Data were statically analyzed, and Troponin curves were designed for each group to be correlated with that of AMI in human. After 7 days, histopathological studies of the surgical group exhibited wide areas of focal fibrosis at the apex and scattered mononuclear inflammatory cells infiltration. While the isoproterenol group showed moderate degree of inflammation with multifocal areas of fibrosis and scattered mononuclear inflammatory cells. However, the doxorubicin group showed more or less normal histology of cardiomyocytes. Biochemical studies reflected a significant difference in serum Troponin levels and peak timing among the groups. The surgical and isoproterenol groups Troponin peaked around 24 hours after the intervention, with higher levels in the surgical group. However, the doxorubicin group showed lower peaks around 36 hours post intervention. Correlations with human AMI histopathology and biochemical markers show more mimicking changes in the surgical group when compared to the other models, followed by the isoproterenol group and least similar in the doxorubicin- induced group. However, the survival rate of rats in the isoproterenol group was superior, followed by the surgical group and the doxorubicin group showed the lowest survival rates. Conclusions Surgical induction of AMI in rats achieves the high similarity to AMI in human but the low survival rates jeopardize the reliability of the model. However, isoproterenol shows sufficient levels of mimicking and higher survival indicating the highest reliability in simulation. Doxorubicin based models are the least reliable.

Resveratrol improves cardiac function and left ventricular fibrosis after myocardial infarction in rats by inhibiting NLRP3 inflammasome activity and the TGF-β1/SMAD2 signaling pathway.

BackgroundSeveral studies have shown that resveratrol (RES), a naturally occurring polyphenol found in many plants, is beneficial for preventing cardiovascular diseases. However, the mechanism underlying the RES-mediated protection against myocardial infarction has not yet been revealed entirely. In this study, we investigated the protective effects of RES on cardiac function in a rat model of acute myocardial infarction (AMI) and the related underlying mechanisms.MethodsMale Sprague-Dawley rats were randomly divided into four groups: Sham (sham operation), Sham-RES, AMI (AMI induction), and AMI-RES. The rat AMI model was established by the permanent ligation of left anterior descending coronary artery method. The rats in the RES-treated groups were gavaged with RES (50 mg/kg/day) daily for 45 days after the Sham operation or AMI induction; rats in the Sham and AMI groups were gavaged with deionized water. Cardiac function was evaluated by echocardiography. Atrial interstitial fibrosis was assessed by hematoxylin-eosin or Masson’s trichrome staining. Real-time PCR and western blotting analyses were performed to examine the levels of signaling pathway components.ResultsRES supplementation decreased the inflammatory cytokine levels, improved the cardiac function, and ameliorated atrial interstitial fibrosis in the rats with AMI. Furthermore, RES supplementation inhibited NLRP3 inflammasome activity, decreased the TGF-β1 production, and downregulated the p-SMAD2/SMAD2 expression in the heart.ConclusionRES shows notable cardioprotective effects in a rat model of AMI; the possible mechanisms underlying these effects may involve the improvement of cardiac function and atrial interstitial fibrosis via the RES-mediated suppression of NLRP3 inflammasome activity and inhibition of the TGF-β1/SMAD2 signaling pathway in the heart.

Phosphatidylserine Supplementation as a Novel Strategy for Reducing Myocardial Infarct Size and Preventing Adverse Left Ventricular Remodeling.

Phosphatidylserines are known to sustain skeletal muscle activity during intense activity or hypoxic conditions, as well as preserve neurocognitive function in older patients. Our previous studies pointed out a potential cardioprotective role of phosphatidylserine in heart ischemia. Therefore, we investigated the effects of phosphatidylserine oral supplementation in a mouse model of acute myocardial infarction (AMI). We found out that phosphatidylserine increases, significantly, the cardiomyocyte survival by 50% in an acute model of myocardial ischemia-reperfusion. Similar, phosphatidylserine reduced significantly the infarcted size by 30% and improved heart function by 25% in a chronic model of AMI. The main responsible mechanism seems to be up-regulation of protein kinase C epsilon (PKC-ε), the main player of cardio-protection during pre-conditioning. Interestingly, if the phosphatidylserine supplementation is started before induction of AMI, but not after, it selectively inhibits neutrophil’s activation, such as Interleukin 1 beta (IL-1β) expression, without affecting the healing and fibrosis. Thus, phosphatidylserine supplementation may represent a simple way to activate a pre-conditioning mechanism and may be a promising novel strategy to reduce infarct size following AMI and to prevent myocardial injury during myocardial infarction or cardiac surgery. Due to the minimal adverse effects, further investigation in large animals or in human are soon possible to establish the exact role of phosphatidylserine in cardiac diseases.

A study of the cardioprotective effect of spermidine: A novel inducer of autophagy.

Acute myocardial infarction (AMI) is an instant death of cardiomyocytes that ends in a large mortality worldwide. Thus, there is a great interest to come up with novel protective approaches for AMI to mount cardiomyocyte survival, enhance postinfarcted cardiac function, and countermand the process of cardiac remodeling. Spermidine has vital roles in vast cellular processes under pathophysiological circumstances. This study aims to enhance our comprehension of the role of autophagy as a possible protective sequel of spermidine supplementation on postinfarction ventricular dysfunction in a rat model of AMI induced by isoproterenol (ISO). Thirty male rats were divided into three groups (control, AMI, and spermidine + AMI). AMI was induced by subcutaneous ISO injections for two consecutive days. Rats were pretreated with spermidine by intraperitoneal injection before induction of AMI. Electrocardiogram (ECG) was recorded in all rats 24 h after the second dose of ISO. Rats were sacrificed after ECG recording, and samples were taken for biochemical assessments. Spermidine intake before induction of AMI in rats significantly attenuated cardiac dysfunction where cardiac enzymes are decreased, and ECG changes induced by ISO are reversed in cardiomyocytes. Spermidine affects the autophagic flux of autophagy-related protein expression (LC3-II, TFEP, and p62). Furthermore, it increased the total antioxidant capacity.

Quercetin protects against experimentally-induced myocardial infarction in rats by an antioxidant potential and concomitant activation of signal transducer and activator of transcription 3.

This study tested if the protective effect of quercetin (QUR) against experimentally-induced acute myocardial infarction (AMI) in rats involves modulating the Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathway. Rats were divided into 6 groups as sham-operated (control), control + QUR, AMI, AMI + QUR, AMI + S3I-210 (a STAT3 inhibitor), and AMI + QUR + S31-201. QUR (50 mg/kg/orally) and S3I-201 (a STAT3 inhibitor) (5 mg/kg/i.p.) were administered for 7 days before the induction of AMI and the experiment was ended 24 h post-AMI. Pre-treatment with QUR reduced the infarct size, improved the left ventricular (LV) functions and the structure of the myofibrils and the mitochondria, and reduced circulatory levels of lactate dehydrogenase (LDH), creatinine-kinase MB (CKMB), and troponin-I. QUR also reduced LV levels of reactive oxygen species (ROS) and malondialdehyde (MDA), inhibited the opening of the mitochondria transition pores (mtPTP), and reduced protein levels of cytochrome-C, cleaved caspase-3 and p-JAK2 (Tyr1007/1008) in the LVs of AMI rats. In the LV of both the control and AMI rats, QUR didn't affect the levels of p-JAK2 but significantly increased the levels of total glutathione (GSH) and manganese superoxide dismutase (MnSOD), reduced the levels of Bax and the nuclear levels and activity of NF-κB p65, tumor necrosis-factors-α (TNF-α), interleukin-6 (IL-6), and p-STAT1 (Ser727) but further increased the levels of p-STAT3 (Ser727). All these effects exerted by QUR were partially reversed but the decrease in nuclear protein levels and activity of NFκB, levels of TNF-α and IL-6, and pSTAT3 were completely prevented by co-administration of S3I-201. In conclusion, QUR protects against MI by upregulation of antioxidants and activation of STAT3.

Abstract 17087: Mesenchymal Stem Cell-Derived Extracellular Vesicle Therapy Delivered in a Hydrogel Preserves Hemodynamic Function Following Myocardial Infarction

Introduction: Mesenchymal Stem Cell (MSC)-derived Extracellular Vesicles (EVs) are an emerging regenerative therapy for treatment of ischemic cardiomyopathy. In this study, we determine the efficacy of MSC-EV therapy in a shear-thinning hydrogel (STG) delivered via intramyocardial injection to the border zone of rat hearts following myocardial infarction (MI). Hypothesis: MSC EV-loaded STGs will preserve hemodynamic function and minimize ventricular scar formation in a rat model of acute MI. Methods: EVs were isolated from MSCs by PEG precipitation, and the EV proteome was characterized by MaxQuant 1.5.1.2 and Metacore analysis software. Varying concentrations of EVs were administered to rats following induction of acute MI by ligation of the left anterior descending artery. EVs were delivered in either sterile phosphate buffered saline (PBS) or STG for sustained EV release. Chronic injury was assessed at 4 weeks post-MI through transthoracic echocardiography, intraventricular pressure-volume loop displacement, and histology. Results: MSC EV proteomic analysis highlighted upregulation of VEGF angiogenic cascades and ILK-mediated proliferative pathways. The mean left ventricle ejection fraction (LVEF) for each treatment group at four weeks is displayed in Table 1. A 20 ug dose of MSC EVs in STG improved LVEF by 19.12% (p<0.05) compared to PBS, with a 90 ug dose of MSC EVs in STG increasing LVEF by 23.56% (p<0.01) (Fig. 1). Conclusions: Intramyocardial injection of MSC EVs in STG post-MI showed concentration dependent improvements in hemodynamics. These findings show that high doses of MSC EV in STG may have potential as a therapy for ischemic cardiomyopathy. Proteomic analysis revealed that angiogenesis, recruitment of cardiac progenitor cells, and immune modulation may be mechanistic drivers of MSC-EV therapy.

Umbilical cord mesenchymal stromal cells engraft and transdifferentiate into cardiomyocyte-like cells following acute myocardial ischemia⋆

ObjectiveHuman umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) gained importance in acute/chronic ischemic cardiomyopathy because of their outstanding regenerative potential in various pathologic conditions. The present study was designed to determine to what extent hUC-MSCs contribute to myocardial regeneration in acute experimental myocardial infarction (MI) in rats. MethodsAnimals were assigned into two groups; the control group received intramyocardial PBS injections, while the hUC-MSC group received calcein-AM-labeled 8.8 × 106/kg hUC-MSCs. Three weeks following the acute MI induction, rats were sacrificed after assessing the left ventricular (LV) function using echocardiography. For the assessment of infarct size, the triphenyl tetrazolium chloride (TTC) test was used in isolated hearts. Collagen-rich scar tissue was demonstrated using Masson’s trichrome staining, followed by the detection of cardiac troponin I (cTnI), α-sarcomeric actin (α-SA), von Willebrand factor (vWF), CD68 and CD206 expressions in control and cell-injected sections. ResultsEchocardiography revealed a significant difference (P = 0.037) in the LV ejection fraction between groups. TTC assays demonstrated a significant difference (P = 0.006) between the groups regarding the ratio of the infarcted LV area. Calcein-AM-loaded cells were identified mostly in ischemic myocardium. Transplanted cells also expressed human-specific cTnI, providing concrete proof of transdifferentiation into cardiomyocytes, and α-SA. vWF+ cells verified the neovascularization in the ischemic myocardium. Finally, a slight shift from pro-inflammatory to anti-inflammatory macrophages (CD68+/CD206+) was noted in both groups. ConclusionsWe found that the intramyocardial transplanted hUC-MSCs engrafted and partially transdifferentiated into cardiomyocytes, reduced scar formation, and induced angiogenesis through the association of pro/anti-inflammatory macrophages.

Protective effect of sonic hedgehog signaling pathway activation on acute myocardial infarction.

To study changes in the sonic hedgehog (Shh) signaling pathway in acute myocardial infarction (AMI) and the protective effect of changes in Shh signaling pathway activity on AMI, specific pathogen-free (SPF) C57BL/6 mice were treated with left anterior descending (LAD) ligation to establish an AMI model. The samples were collected on the 1st, 3rd, 14th, and 21st days after AMI induction. After the operations, the mice were administered the Shh signaling pathway receptor agonist SAG1.3 (5 mg/kg/d) and antagonist SANT-1 (3.3 mg/kg/d) by intraperitoneal injection. The myocardial ischemia model was established by oxygen glucose deprivation (OGD) in vitro. The AMI mouse model and the in vitro OGD-induced myocardial ischemia model were established. The Smo agonist SAG1.3 was used to activate the Shh signaling pathway, thereby reducing the expression of Bcl-2 and Bax. The number of apoptotic cells was reduced. Administration of the antagonist SANT-1 inhibited Shh signaling pathway activity by increasing the expression of Bcl-2 and Bax, and the number of apoptotic cells increased. In conclusion, activation of the Shh signaling pathway improved cardiac functions and myocardial remodeling and reduced the apoptosis of myocardial cells.

Tagged cine magnetic resonance imaging to quantify regional mechanical changes after acute myocardial infarction

PurposeThe conventional volumetric approaches of measuring cardiac function are load-dependent, and are not able to discriminate functional changes in the infarct, transition and remote myocardium. We examined phase-dependent regional mechanical changes in the infarct, transition and remote regions after acute myocardial infarction (MI) in a preclinical mouse model using cardiovascular magnetic resonance imaging (CMR). MethodsWe induced acute MI in six mice with left anterior descending coronary artery ligation. We then examined cardiac (infarct, transition and remote-zone) morphology and function utilizing 9.4 T high field CMR before and 2 weeks after the induction of acute MI. Myocardial scar tissue was evaluated by using CMR with late gadolinium enhancement (LGE). After determining global function through volumetric analysis, regional wall motion was evaluated by measuring wall thickening and radial velocities. Strain rate imaging was performed to assess circumferential contraction and relaxation at the myocardium, endocardium, and epicardium. ResultsThere was abnormal LGE in the anterior walls after acute MI suggesting a successful MI procedure. The transition zone consisted of a mixed signal intensity, while the remote zone contained viable myocardium. As expected, the infarct zone had demonstrated severely decreased myocardial velocities and strain rates, suggesting reduced contraction and relaxation function. Compared to pre-infarct baseline, systolic and diastolic velocities (vS and vD) were significantly reduced at the transition zone (vS: −1.86 ± 0.16 cm/s vs −0.68 ± 0.13 cm/s, P < 0.001; vD: 1.86 ± 0.17 cm/s vs 0.53 ± 0.06 cm/s, P < 0.001) and remote zone (vS: −1.86 ± 0.16 cm/s vs −0.65 ± 0.12 cm/s, P < 0.001; vD: 1.86 ± 0.16 cm/s vs 0.51 ± 0.04 cm/s, P < 0.001). Myocardial peak systolic and diastolic strain rates (SRS and SRD) were significantly lower in the transition zone (SRS: −4.2 ± 0.3 s−1 vs −1.3 ± 0.2 s−1, P < 0.001; SRD: 3.9 ± 0.3 s−1 vs 1.3 ± 0.2 s−1, P < 0.001) and remote zone (SRS: −3.8 ± 0.3 s−1 vs −1.4 ± 0.3 s−1, P < 0.001; SRD: 3.5 ± 0.2 s−1 vs 1.5 ± 0.4 s−1, P = 0.006). Endocardial and epicardial SRS and SRD were similarly reduced in the transition and remote zones compared to baseline. ConclusionsThis study, for the first time, utilized state-of-the art high-field CMR algorithms in a preclinical mouse model for a comprehensive and controlled evaluation of the regional mechanical changes in the transition and remote zones, after acute MI. Our data demonstrate that CMR can quantitatively monitor dynamic post-MI remodeling in the transition and remote zones, thereby serving as a gold standard tool for therapeutic surveillance.

Antioxidant and Anti-Inflammatory Effects of Curcumin Nanoparticles on Drug-Induced Acute Myocardial Infarction in Diabetic Rats.

We have investigated the cardio-protective effects of pretreatment with curcumin nanoparticles (CUN) compared to conventional curcumin (CUS) on the changes in oxidative stress parameters and inflammatory cytokine levels during induced acute myocardial infarction (AMI) in rats with diabetes mellitus (DM). DM was induced with streptozotocin, and AMI with isoproterenol. Eight groups of seven Wister Bratislava rats were included in the study. The N-C was the normal control group, AMI-C was the group with AMI, DM-C was the group with DM, and DM-AMI-C was the group with DM and AMI. All four groups received saline solution orally during the whole experiment. S-DM-CUS-AMI and S-DM-CUN-AMI groups received saline for seven days prior to DM induction and continued with CUS (200 mg/kg bw, bw = body weight) for S-DM-CUS-AMI and CUN for S-DM-CUN-AMI (200 mg/kg bw) for 15 days before AMI induction. The CUS-DM-CUS-AMI group received CUS (200 mg/kg bw), while the CUN-DM-CUN-AMI received CUN (200 mg/kg bw) for seven days prior to DM induction, and both groups continued with administration in the same doses for 15 days before AMI induction. CUS and CUN prevented elevation of creatine kinase, creatine kinase-MB, lactate dehydrogenase in all groups, with better results in the CUN (S-DM-CUN-AMI and CUN-DM-CUN-AMI groups). CUS and CUN significantly reduced serum levels of oxidative stress markers (malondialdehyde, the indirect assessment of nitric oxide synthesis, and total oxidative status) and enhanced antioxidative markers (total antioxidative capacity and thiols, up to 2.5 times). All groups that received CUS or CUN showed significantly lower serum levels of tumor necrosis factor-alpha, interleukin-6, and interleukin-1β. The best antioxidative and anti-inflammatory effects were obtained for the group that received CUN before DM induction (CUN-DM-CUN-AMI group). Pretreatment with CUN proved higher cardio-protective effects exerting an important antioxidative and anti-inflammatory impact in the case of AMI in DM.

Abstract 140: Efficacy Evaluation of Transplantation of Three-Dimensional Adipose-derived Stem Cell Sheet With Enhanced Angiogenesis Into Cardiovascular Disease

Integration of adipose-derived stem cells (ASCs) and cell sheet engineering technology has received much interest in the regenerative medicine. First of all, sphere formation of ASCs (sph-ASCs) were successfully produced by poly-2-hydroxyethyl methacrylate (poly-HEMA)-coated plates as we previously reported. Sph-ASCs showed increased expression of angiogenic growth factors and cytokine secretion compared to adherent ASCs. Significantly increased expression of HIF-1α and decreased expression of cleaved caspase-3 were detected in sph-ASCs compared to adherent ASCs. Moreover, ASC sheets were formed using thermo-responsive plates and sph-ASCs were seeded to produce ASC sheets covered with sph-ASCs (sph-ASC sheets). After 48 hrs of incubation, the cross-section of sph-ASC sheets revealed mixed and multi-layered of sph-ASCs and ASC sheets. Sph-ASC sheets showed the positive expression of HIF-1α and angiogenic markers such as FGF-2, CD31, PDGFb, and CD144, especially higher in sph-ASC-covered sites. In addition, cytokine arrays of secretome revealed that sph-ASCs and sph-ASC sheets showed augmented angiogenic potential compared to adherent ASCs. Furthermore, four groups of AMI induction only (sham), intramyocardial injection of sph-ASC, ASC sheet transplantation, and sph-ASC sheet transplantation were compared using acute myocardial infarction (AMI) rat models. After 6 weeks of transplantation, echocardiography revealed that significantly improved ejection fraction and fraction shortening in sph-ASC sheet group compared to sham, sph-ASC, and ASC sheet groups. In conclusion, transplantation of sph-ASC sheets showed enhanced neovascularization in AMI animal models. These results indicated that the use of ASC sheets as a novel tissue engineering approach to improve the cardiac and vascular function.

Development of a Novel Sodium-Hydrogen Exchanger Inhibitor for Heart Failure

This study was designed to determine the potential therapeutic effects of a new sodium-hydrogen exchanger (NHE-1) inhibitor in the rat coronary artery ligation model of chronic heart failure. After the induction of acute myocardial infarction, rats were entered into a randomly designed pilot dose study from 0.3 mg/kg, 1.0 mg/kg, and 3.0 mg/kg. Solid state micrometer hemodynamics, echocardiographic, and pressure-volume relationships were measured after 6 weeks of treatment. Treatment with this NHE-¬1 inhibitor at 3 mg/kg increased (P<0.05) ejection fraction from 23±3% (N=6) to 33±2% (N=13), while the 1 mg/kg dose decreased (P<0.05) the infarct size in CHF rats from 21.7±1.4% (N=7) to 15.9±0.7% (N=3) and prevented (P<0.05) dilata¬tion of the left ventricle in CHF rats in diastole (1.0±0.1 cm, N=6) to 0.9±0.1 cm, N=10) and in systole (0.9±0.1 cm, N=6) to 0.8±0.1, N=10). These study results suggest that this new NHE-1 inhibitor may be potentially useful in treating CHF with an improvement in maladaptive left ventricle remodeling. Because the mechanism of action of this agent is entirely different than the currently applied approach in treating CHF that focuses on aggressive neuro-hormonal blockade and because this agent does not adversely affect important hemodynamic variables, further investigations with this agent may be warranted.

Novel porcine model of acute myocardial infarction using polyethylene terephthalate

Acute myocardial infarction (AMI) is considered the major cause of mortality in the world. Tremendous animal studies are performed to develop novel therapeutics, and this study aimed to induce porcine myocardial infarction model by using polyethylene terephthalate (PET). Coronary guidewire was placed in left anterior descending artery (LAD). The balloon angioplasty catheter was inserted at the back of the PET. The balloon catheter was carefully pushed forward, until the balloon marker was located in mid-LAD. Coronary angiography was performed pre- and post-occlusion at 28 days by C-arm. Histologic analysis of heart tissue was performed 28 days after inducing AMI. Thirty three pigs were anesthetized and underwent percutaneous coronary catheterization. All pigs were successfully embolized in mid-LAD by PET. Fifteen pigs died due to ventricular fibrillation during post-anesthetic recovery time, and overall experiment mortality was 45.5%. In 2,3,5-triphenyl tetrazolium chloride staining, gross finding of the ischemic heart lesion showed firm and white area of infarction associated with the apex and left ventricular posterior wall. Infarct on H&amp;E-stained sections demonstrated a region without myocytes and rich with cardiomyocyte with atypical nuclei. Successful induction of AMI by using PET may provide the pathophysiological information of ischemic heart disease and improvement of therapy development for AMI.

Influence of Local Myocardial Infarction on Endothelial Function, Neointimal Progression, and Inflammation in Target and Non-Target Vascular Territories in a Porcine Model of Acute Myocardial Infarction.

BackgroundPatients with acute myocardial infarction (AMI) have worse clinical outcomes than those with stable coronary artery disease despite revascularization. Non-culprit lesions of AMI also involve more adverse cardiovascular events. This study aimed to investigate the influence of AMI on endothelial function, neointimal progression, and inflammation in target and non-target vessels.MethodsIn castrated male pigs, AMI was induced by balloon occlusion and reperfusion into the left anterior descending artery (LAD). Everolimus-eluting stents (EES) were implanted in the LAD and left circumflex (LCX) artery 2 days after AMI induction. In the control group, EES were implanted in the LAD and LCX in a similar fashion without AMI induction. Endothelial function was assessed using acetylcholine infusion before enrollment, after the AMI or sham operation, and at 1 month follow-up. A histological examination was conducted 1 month after stenting.ResultsA total of 10 pigs implanted with 20 EES in the LAD and LCX were included. Significant paradoxical vasoconstriction was assessed after acetylcholine challenge in the AMI group compared with the control group. In the histologic analysis, the AMI group showed a larger neointimal area and larger area of stenosis than the control group after EES implantation. Peri-strut inflammation and fibrin formation were significant in the AMI group without differences in injury score. The non-target vessel of the AMI also showed similar findings to the target vessel compared with the control group.ConclusionIn the pig model, AMI events induced endothelial dysfunction, inflammation, and neointimal progression in the target and non-target vessels.