Model Of Myocardial Ischemia Research Articles

Metformin Preconditioning Augments Cardiac Perfusion and Performance in a Large Animal Model of Chronic Coronary Artery Disease.

To test the efficacy of metformin (MET) during the induction of coronary ischemia on myocardial performance in a large animal model of coronary artery disease (CAD) and metabolic syndrome (MS), with or without concomitant extracellular vesicular (EV) therapy. Although surgical and endovascular revascularization are durably efficacious for many patients with CAD, up to one-third are poor candidates for standard therapies. For these patients, many of whom have comorbid MS, adjunctive strategies are needed. EV therapy has shown promise in this context, but its efficacy is attenuated by MS. We investigated whether MET pretreatment could ameliorate therapeutic decrements associated with MS. Yorkshire swine (n = 29) were provided a high-fat diet to induce MS, whereupon an ameroid constrictor was placed to induce CAD. Animals were initiated on 1000 mg oral MET or placebo; all then underwent repeat thoracotomy for intramyocardial injection of EVs or saline. Swine were maintained for 5 weeks before the acquisition of functional and perfusion data immediately before terminal myocardial harvest. Immunoblotting and immunofluorescence were performed on the most ischemic tissue from all groups. Regardless of EV administration, animals that received MET exhibited significantly improved ejection fraction, cardiac index, and contractility at rest and during rapid myocardial pacing, improved perfusion to the most ischemic myocardial region at rest and during pacing, and markedly reduced apoptosis. MET administration reduced apoptotic cell death, improved perfusion, and augmented both intrinsic and load-dependent myocardial performance in a highly translatable large animal model of chronic myocardial ischemia and MS.

T-wave Peak-to-End Changes Quantified by Time-Warping Predicts Ventricular Fibrillation in a Porcine Myocardial Infarction Model.

The T-peak-to-T-end ( Tpe) interval has shown potential in predicting ventricular arrhythmic risk. It is an appealing index to be measured during ischemia since it is less influenced by ST-segment changes than the early part of the T wave. A time-warping-based index, derived from a spatially transformed PCA lead, [Formula: see text], quantifying changes in the Tpe morphology, has previously demonstrated utility in tracking repolarization changes induced by a 5-minute ischemia model in humans. The value of [Formula: see text] as a predictor of ventricular fibrillation (VF) episodes is assessed in a porcine model of myocardial ischemia with ischemia maintained for 40 minutes. From 32 pigs undergoing a coronary occlusion, pre-occlusion and occlusion ECG recordings from 10 pigs suffering a VF episode after 10 min of occlusion (Delayed VF) and 16 that did not had any episode during the recording were analyzed. The [Formula: see text] series was measured by comparing Tpe morphologies at different stages of the occlusion relative to the peak-to-end morphology of a baseline T-wave. During baseline, [Formula: see text] remained stationary with an intra-recording median [IQR] value of 1.60 [1.33] ms. During artery occlusion, [Formula: see text] followed a well-marked gradual increasing trend as ischemia progressed, reaching a median of 14.58 [17.72] ms. [Formula: see text] averages were significantly higher ( ) in the VF group than in the Non-VF group at time intervals 0-5, 5-10, 10-15, 15-20, 20-25 min after occlusion onset and at 10-15, 5-10 and 5-0 minutes prior to VF episode, with median values of 12.5, 18.8, 26.8, 24.0, 31.0, 18.6, 25.0 and 28.8 vs 6.3, 7.6, 8.0, 7.8, 7.8, 8.5, 7.2 and 6.0 ms, respectively. The [Formula: see text] interval was also significantly higher in the VF group at all analyzed time periods, but with a lower significance level. Pigs with maximum [Formula: see text] ≥ 20.0 ms and [Formula: see text] ≥ 85.4 ms had significantly higher risk for VF occurring in the early 5-10 minutes interval, with 90.0%/75.0% and 80.0%/69.0% sensitivity/specificity, respectively. Univariate Cox analysis yielded hazard ratios of 12.5 for [Formula: see text] vs 5.5 for [Formula: see text]. The time-warping-based index, [Formula: see text], is a stronger VF predictor than [Formula: see text] during ischemia in a porcine model, advising for further clinical exploration studies in humans.

Hydrogel-Integrated Heart-on-a-Chip Platform for Assessment of Myocardial Ischemia Markers.

Organ-on-a-chip platform scans offer a controllable environment and a physiological similarity to mimic human pathophysiology. In this study, a single-channel PDMS microchip was fabricated, characterized, and optimized to obtain a heart-on-a-chip platform, which is integrated with a hydrogel scaffold suitable for cardiomyocyte growth inside its channel. Single-channel chips with a size of 20 × 12 mm and a channel height ranging from 60 to 100 μm were produced using photolithography and soft lithography techniques. A gelatin-embedded alginate network-based hydrogel was further augmented with 3% (v/v) collagen type I. Pore sizes were in the range of 74-153 μm for H9C2 implantation and biomimicry. The hydrogels are characterized both on PDMS surfaces and in capillaries. The primary feature distinguishing this study from previous microchip studies is that it mimics the cell microenvironment much better using different hydrogel formulations instead of creating a 2D cell culture by passing fluids, such as fibronectin, for cell adhesion. Instead of using complex microchip designs, the chip system we created intends to provide a physiologically relevant copy by using a 3D cell culture to its advantage and a simple, single-channel architecture. The microchip study was combined with cardiomyocytes to create the heart-on-a-chip system and tested under normoxic and hypoxic conditions to create a myocardial ischemia model inside this channel. As a result, this heart-on-a-chip platform was shown to be utilized for the detection of several small-size biomarkers such as adenosine, ADP, lactic acid, l-isoleucine, l-glutamic acid, and oxidized glutathione via LC-MS/MS from control conditions and a myocardial ischemia model. Cell-embedded and hydrogel matrix-supported versions of this heart-on-a-chip system were successfully prepared and shown to provide powerful outputs with myocardial ischemia markers. In light of this research, these outputs aim to develop simple and biologically effective organ-on-a-chip systems for future research.

Plasma metabolic profiling reveals that crude and processed Polygonatum cyrtonema hua extract ameliorates myocardial ischemia-induced damage by regulating branched-chain amino acid and energy metabolism

Polygonatum cyrtonema Hua and its processed products have demonstrated cardio-protective effects, though the underlying mechanisms remain unclear. In this study, plasma metabolic profiling and pattern recognition were employed to explore the cardio-protective mechanisms of both crude and processed P. cyrtonema in a myocardial ischemia model induced by ligation, using gas chromatography-mass spectrometry. Post-modeling, plasma levels of creatine kinase-MB, lactate dehydrogenase, troponin T, and malondialdehyde were significantly elevated but were notably reduced after treatment. Conversely, plasma levels of glutathione peroxidase and superoxide dismutase, which were significantly decreased post-modeling, were restored following treatment. Hematoxylin-eosin (HE) and Masson staining revealed that both crude and processed P. cyrtonema effectively reduced inflammatory infiltration and fibrosis in cardiac tissue. Metabolic profiling identified 34 differential endogenous metabolites in the treatment groups, with 19 confirmed using standard compounds. The linear correlation coefficients (R2) for these standards ranged from 0.9960 to 0.9996, indicating high accuracy. The method exhibited excellent precision and repeatability, with relative standard deviation (RSD) values below 8.57%. Recovery rates were between 95.02% and 105.15%, and the stability of the standard compounds was confirmed after three freeze–thaw cycles, with RSD values under 4.42%. Both crude and processed P. cyrtonema were found to alleviate myocardial ischemia symptoms by regulating branched-chain amino acid metabolism and energy metabolism. These findings provide a solid foundation for the potential clinical use of this herb and its processed products in treating heart disease.

Abstract Mo052: Electrocardiographic behavior, arrhythmias, and mortality in two calcium management strategies (cytoplasmic and mitochondrial) in hearts under ischemia.

Background: The disruption of calcium homeostasis in ischemic hearts is determinant for triggering the arrhythmic phenomena and death. Interventions that act on calcium levels in cytoplasm and mitochondria might interrupt or minimize these outcomes. Trisulfate disaccharide (TD) acts by accelerating the sodium-calcium exchanger, decreasing cytosolic calcium levels. Ruthenium red (RuR) is a mitochondrial uniporter inhibitor that blocks calcium influx into mitochondria. Both agents can be useful in calcium overload elicited by myocardial ischemia (MI), modifying electrocardiographic (EKG) parameters that predict arrhythmia, arrhythmic phenomena, and cell death. Objectives: To compare the behavior of Tp-Te and QTc EKG intervals, arrhythmia rates, and mortality in ischemic hearts under the action of TD and RuR. Materials and Methods: Adult Wistar rats (n=24) were divided in 3 groups, i.e, Control: MI with no treatment (n=8), TD: MI treated with TD 0.2 mg/kg IV (n=8), and RuR:MI treated with RuR 1 mg/kg IV (n=8). Rats were monitored by EKG and submitted to surgical MI by ligation of anterior descending artery during 10 minutes followed by reperfusion thereafter. The Tp-Te and QT intervals were analyzed before and at 10 minutes of ischemia and 10 minutes after the onset of reperfusion. The incidence of arrhythmias and mortality were determined throughout the recording time. Results: The Tp-Te and QTc intervals increased during ischemia in all groups (Control, TD and RuR), which were normalized after 10 minutes reperfusion only in TD group. The observed arrhythmias (atrioventricular block, ventricular tachycardia, and torsade of pointes) had a higher incidence in the control group and the lower incidences, with statistically significant differences, were achieved in TD and RuR groups, whose incidence was similar in these both groups. Sustained arrhythmias led to a 50% mortality in the control group and 25% in RuR group. No mortality in TD group was observed. Conclusion: The strategy of decreasing cytosolic calcium levels by the action of TD has proved to be more effective than the blockade of mitochondrial calcium uptake by RuR, with further normalization of EKG parameters predictors of mortality, and absence of sustained arrhythmias and mortality, suggesting that the management of cytosolic calcium levels is more effective than only the management of mitochondrial calcium in MI model.

Anti-myocardial ischemic injury effects and mechanisms of cryptotanshinone in regulating macrophage polarisation through Dectin-1 signalling pathway

The aim of this study was to investigate the potential mechanism by which cryptotanshinone(CTS) may exert its anti-myo-cardial ischemic effect through the regulation of macrophage polarization via the dendritic cell-associated C-type lectin 1(Dectin-1) signaling pathway. Male C57BL/6 mice, aged six weeks, were utilized to establish myocardial ischemia models and were subsequently divided into five groups: sham, model, CTS low-dose(21 mg·kg~(-1)·d~(-1)), CTS high-dose(84 mg·kg~(-1)·d~(-1)), and dapagliflozin(0.14 mg·kg~(-1)·d~(-1)). The cardiac function, serum enzyme levels, Dectin-1 expression, macrophage polarization, and neutrophil infiltration in the myocardial infarction area were assessed in each group. An in vitro model of M1-type macrophages was constructed using lipopolysaccharide/interfe-ron-γ(LPS/IFN-γ) stimulated RAW264.7 cells to investigate the impact of CTS on macrophage polarization and to examine alterations in key proteins within the Dectin-1 signaling pathway. In the CTS group, compared to the model group mice, there was a significant improvement in the cardiac function and myocardial injury, along with a notable increase in the ratio of M2/M1-type macrophages in the myocardial infarcted area and a decrease in neutrophil infiltration. Additionally, Dectin-1 exhibited low expression. The results of in vitro experiments demonstrated that CTS can decrease the expression of M1-type marker genes and increase the expression of M2-type marker genes. Besides, it can decrease the levels of Dectin-1 and the phosphorylation of its associated proteins, including spleen tyrosine kinase(Syk), protein kinase B(Akt), nuclear factor-kappaB p65(NF-κB p65), and extracellular signal-regulated protein kinases(ERK1/2). Additionally, CTS was found to enhance the phosphorylation of signal transducer and activator of transcription-6(STAT6). The above results suggest that CTS exerts its anti-myocardial ischemic injury effect by regulating macrophage polarization through the Dectin-1 signaling pathway.

Ginsenoside Rb2 Inhibits the Pyroptosis in Myocardial Ischemia Progression Through Regulating the SIRT1 Mediated Deacetylation of ASC.

Myocardial ischemic (MI) injury is a common cardiovascular disease, and the potential therapeutic effects of ginsenoside Rb2 (Rb2) have been lately the focus of interest. Therefore, this study aimed to investigate the effects of Rb2 on pyroptosis of cardiomyocytes in MI progression. An in vitro MI model was developed by subjecting rat's cardiomyocytes (H9c2) to hypoxia/reoxygenation (H/R). The cell viability was determined by CCK-8 assay, while cell death was analyzed by propidium iodide staining. Similarly, pyroptosis-related protein levels and acetylation levels of apoptosis-associated speck-like protein containing a CARD (ASC) were detected by western blotting, and the relationship between Sirtuin 1 (SIRT1) and ASC was confirmed by co-immunoprecipitation (Co-IP) assay. Moreover, hematoxylin-eosin (H&E) and triphenyl tetrazolium chloride staining were used to study pathological structure and infarct size. It was found that post-Rb2 treatment significantly increased the cell viability and decreased the cell death and lactic dehydrogenase release, while the increased gasdermin D-N, NOD-like receptor thermal protein domain-associated protein 3, ASC, and cleaved-caspase-1 protein levels were significantly decreased in H/R-stimulated H9c2 cells. Moreover, the acetylation levels of H92c cells were decreased post-Rb2 treatment via increasing SIRT1 levels, while knocking down SIRT1, translated into an increase in ASC acetylation levels, leading to the increase in ASC protein stability and expressions. Additionally, the Rb2 effects on pyroptosis in H/R-stimulated H92c cells were reversed by overexpressing ASC, while reduced myocardial tissue damage was observed in MI rats following in vivo Rb2 treatment. Rb2 treatment inhibited pyroptosis in MI progression by decreasing the ASC levels. Mechanistically, Rb2 treatment increased the SIRT1 levels, further increasing the acetylation levels of ASC and decreasing the protein stability of ASC.

Effects of diet-induced metabolic syndrome on cardiac function and angiogenesis in response to the sodium-glucose cotransporter-2 inhibitor canagliflozin

IntroductionSodium-glucose cotransporter-2 inhibitors are antidiabetic medications that have been shown to decrease cardiovascular events and heart failure-related mortality in clinical studies. We attempt to examine the complex interplay between metabolic syndrome and the sodium-glucose cotransporter-2 inhibitor canagliflozin (CAN) in a clinically relevant model of chronic myocardial ischemia. MethodsTwenty-one Yorkshire swine were fed a high-fat diet starting at 6 weeks of age to induce metabolic syndrome. At 11 weeks, all underwent placement of an ameroid constrictor around the left circumflex coronary artery to induce chronic myocardial ischemia. After 2 weeks, swine received either control (CON) (n = 11) or CAN 300 mg by mouth daily (n = 10) for 5 weeks, whereupon all underwent terminal harvest. ResultsThere was a significant increase in cardiac output and heart rate with a decrease in pulse pressure in the CAN group compared with CON (all P values < .05). The CAN group had a significant increase in capillary density (P = .02). There was no change in myocardial perfusion or arteriolar density. CAN induced a significant increase in markers of angiogenesis, including Phospho-endothelial nitric oxide synthase, Endothelial nitric oxide synthase, vascular endothelial growth factor receptor-1, heat shock protein 70, and extracellular signal-regulated kinases (all P values < .05), plausibly resulting in capillary angiogenesis. ConclusionsCAN treatment leads to a significant increase in capillary density and augmented cardiac function in a swine model of chronic myocardial ischemia in the setting of metabolic syndrome. This work further elucidates the mechanism of sodium-glucose cotransporter-2 inhibitors in patients with cardiac disease; however, more studies are needed to determine if this increase in capillary density plays a role in the improvements seen in clinical studies.

Molecular mechanism of Danxiong Tongmai Granules in treatment of coronary heart disease.

Danxiong Tongmai Granules (DXTMG) are widely utilized in treating coronary heart disease (CHD) in China. This study aims to explore the molecular mechanisms underlying the therapeutic effects of DXTMG on CHD by employing a network pharmacology approach, complemented with experimental validation. Traditional Chinese Medicine (TCM) compounds and targets were identified via searches in the BATMAN-TCM database, and the GeneCards database was used to obtain the main target genes involved in CHD. We combined disease targets with the drug targets to identify common targets. The "TCM-compound-target" network was plotted using Cytoscape 3.7.2 software and a protein-protein interaction (PPI) network was constructed using the STRING database from which core targets were obtained. Gene ontology (GO) function analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed for common drug-disease targets using R Version 4.0.4 (64 bit) software. Molecular docking of core protein-small molecule ligand interaction was modeled using AutoDock software. A molecular dynamics simulation was conducted on the optimal protein-small molecule complex identified through molecular docking, using Amber18 software. The rat model for myocardial ischemia was established through pre-gavage administration of DXTMG, followed by dorsal hypodermic injection of isoprenaline. Myocardial tissues from the rats were analyzed using hematoxylin and eosin (HE) staining and Masson's trichrome staining. Relevant targets were validated by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry. 162 potential targets of DXTMG involved in CHD were identified. These included INS, ALB, IL-6 and TNF according to PPI network studies. GO enrichment analysis identified a total of 3365 GO pathways, including 3049 biological process pathways (BP) concerned with the heart and circulatory system; 109 cellular component (CC) pathways, including cation channels and membrane rafts and 207 molecular function (MF) pathways related to receptor ligands and activators. KEGG analysis revealed a total of 137 pathways (P < 0.05), including those related to AGE-RAGE signaling associated with diabetic complications, fluid shear stress and atherosclerosis. The results of molecular docking and molecular dynamics simulations demonstrated the robust binding affinity between the compounds and target proteins. Animal experiment findings indicated that, compared with the model group, the DXTMG group effectively ameliorated inflammation and fibrosis in rat myocardial tissues, reduced LDH, cTn-I, and MDA levels (P < 0.05, P < 0.01), elevated SOD and GSH-PX levels (P < 0.05), and reduced the percentage of positive area for IL-6 and TNF-α (P < 0.05). This study preliminarily suggests that DXTMG can modulate oxidative stress, inflammation response, and cardiomyocyte regulation, thereby mitigating the onset and progression of CHD.

Morphine timing-dependent modulation of TRPV1 phosphorylation correlates with differential morphine effects on myocardial ischemia/reperfusion injury

Opioids are used for pain relief in patients suffering from acute myocardial ischemia or infarction. Clinical and laboratory studies demonstrate that morphine treated patients or the experimental animal model suffering acute myocardial ischemia and reperfusion, may worsen myocardial viability. As transient receptor potential vanilloid 1 (TRPV1) plays important roles in pain sensation and cardio-protection, we query whether opioids may exacerbate myocardial viability via interaction with TRPV1 activity in the pain relief. We found the co-expressions of TRPV1 and opioid μ, δ and κ receptors in adult rat cardiomyocytes. Intravenous injection of morphine (0.3 mg/kg) at 20 min after induction of myocardial ischemia, in the rat model of acute myocardial ischemia and reperfusion, induced significant reduction of phosphorylated TRPV1 (p-TRPV1) in the ventricular myocardium and increase in serum cardiac troponin I (cTnI), compared with the ischemia/reperfusion controls (all P < 0.05). The effects of morphine were completely reversed by selective opioid μ, δ and κ receptor antagonists. While significant upregulation of p-TRPV1 (P < 0.05) and improvement of ±dP/dt max (all P < 0.05) were detected in the animals giving the same dose of morphine before induction of myocardial ischemia. The changes in p-TRPV1 correlate with the alterations of cTnI (r = −0.5840, P = 0.0283) and ±dP/dt max (r = 0.8084, P = 0.0005 and r = −0.8133, P = 0.0004, respectively). The findings of this study may indicate that potentiation and attenuation of TRPV1 sensitivity correlate with the improvement of the cardiac performance and the aggravation of myocardial viability, respectively, by giving morphine before and during myocardial ischemia and reperfusion.

Pharmacokinetic-Pharmacodynamic Correlation Analysis of Rhodiola crenulata in Rats with Myocardial Ischemia.

The pharmacokinetics (PK) of Rhodiola crenulata in rats were studied, and pharmacokinetic-pharmacodynamic (PK-PD) correlation analysis was performed to elucidate their time-concentration-effect relationship. The myocardial ischemia model was made with pituitrin. Rats were divided into sham operation, sham operation administration, model, and model administration groups (SG, SDG, MG, and MDG, respectively; n = 6). Blood was collected from the fundus venous plexus at different time points after oral administration. The HPLC-QQQ-MS/MS method was established for the quantification of five components of Rhodiola crenulata. CK, HBDH, SOD, LDH, and AST at different time points were detected via an automatic biochemical analyzer. DAS software was used to analyze PK parameters and PK-PD correlation. The myocardial ischemia model was established successfully. There were significant differences in the PK parameters (AUC0-t, AUC0-∞, Cmax) in MDG when compared with SDG. Two PD indicators, CK and HBDH, conforming to the sigmoid-Emax model, had high correlation with the five components, which indicated a delay in the pharmacological effect relative to the drug concentration in plasma. The difference in the PK parameters between modeled and normal rats was studied, and the time-concentration-effect of composition and effect indicators were investigated. This study can provide reference for the rational clinical application of Rhodiola crenulata and for related studies of other anti-myocardial ischemia drugs.

Investigation of the effects of cilostazol on the myocardial ischemia-reperfusion injury of rats.

&lt;b&gt;&lt;i&gt;Background&lt;/i&gt;&lt;/b&gt;. Myocardial ischemia, occurring as a consequence of imbalance between oxygen supply and demand, causes a rapid metabolic and structural&lt;br /&gt; impairment within the tissue. After a period of ischemia, sudden onset of reperfusion causes a transition to aerobic metabolism within living cells. Afterwards, emerging substrates initiate a chain of reactions leading to tissue injury. This situation is called “ischemia reperfusion injury”. Despite all technical advancements in anesthesia, myocardial protection and cardiac surgical techniques, we still face the clinical reflections of ischemia reperfusion (IR) injury.&lt;br /&gt; &lt;b&gt;&lt;i&gt;Materials and methods&lt;/i&gt;&lt;/b&gt;. The protective effect of cilostasole on IR injury in an animal model of experimental myocardial ischemia and reperfusion was investigated. In this regional myocardial ischemia model, male Wistar-Albino rats were used as subjects and they were allocated into three groups; ischemia (n=8), sham (n=8), and cilostazole (n=8). LAD was occluded for 45 minutes, and then reperfused for three hours. Rats received Cilostazole 20 mg/kg/d by gastric gavage once daily. During IR hemodynamic parameters were recorded. Serum analysis for CK-MB and Troponin T were analysed at 180th minute of ischemia. Ischemic zone was measured by dying with Evans Blue and infarct area was measured by dying with triphenyltetrazolium chloride.&lt;br /&gt; &lt;b&gt;&lt;i&gt;Results.&lt;/i&gt;&lt;/b&gt; Before the onset of LAD occlusion, as well as at 25th, 60th and 120th minutes of occlusion, all groups were similar in terms of blood pressure and pulse rate.&lt;br /&gt; The total area, affected area and necrotic area were calculated by using formulas; affected area ratio= affected area/total area X 100, necrotic area ratio = necrotic area/total affected area X 100, necrotic area and affected area ratio = necrotic area /affected area X 100.&amp;nbsp; Affected area and total area ratio was significantly higher in IR group, compared with cilostazole group (t=8.965; p&amp;lt;0.001). Similarly, necrotic area and total area ratio was higher in IR group, compared with cilostazole group (t=8.965; p&amp;lt;0.001). The necrotic area and affected area ratios were similar in IR and cilostazole groups (t=0.245; p=0.810). CK-MB level differences were not statistically significant between two groups (Z=0.382; p=0.721).&lt;br /&gt; Troponin levels were similar between IR and cilostazole groups and the difference was not statistically significant (Z=0.630; p=0.574). Pathological specimens of the heart were scanned for myocytolysis, PMNL and hemorrhage.&amp;nbsp; The difference between mean value of MDA enzyme levels were statistically significant (p&amp;lt;0.001) between all groups.&amp;nbsp; MDA enzyme levels, from higher to lower was IR, cilostazole and Sham group.&amp;nbsp; SOD levels (F=5.910; p=0.009) were significantly lower in Sham group when compared with IR group (p=0.008). The differences between Sham and cilostazole groups and IR and cilostazole gropus were not statistically significant (p=0.008). According to planimetric values and enzyme levels, cilostazole was found to be effective in reducing the ischemic zone, without effecting the necrotic zone in cardiac ischemia reperfusion damage. Therefore cilostazole has protective effects agains ischemia reperfusion damage.&lt;br /&gt; &lt;br /&gt; &lt;b&gt;Conclusion&lt;/b&gt;.&amp;nbsp;This study explored how cilostazol affects myocardial ischemia-reperfusion injury in rats, finding that cilostazol administration during reperfusion may protect against such injury. Through various analyses, we observed positive outcomes associated with cilostazol treatment, suggesting its potential in reducing myocardial damage. Further research is needed to understand the underlying mechanisms and optimize therapeutic strategies, but our findings highlight cilostazol's promise in improving clinical outcomes in cardiac interventions.

Experimental models of myocardial ischemia: classical approaches and innovations (review)

Myocardial ischemia is the basis for many acute and chronic conditions with great social significance. Therefore, experimental models that describe ischemia development in humans are necessary for a better understanding of the pathophysiology of these conditions and the development of medical and surgical methods of treatment.Aim: To compare current approaches to experimental modeling of myocardial ischemia considering the pathogenetic features of the simulated processes. The manuscript describes the main experimental models of myocardial ischemia: in vitro cellular models, ex vivo isolated heart models, in vivo animal models, the principal components of the ‘heart-on-chip’ model and the possibilities of in silico modeling. The criteria for choosing a specific model of ischemia by pathophysiological approach, advantages and limitations of the models are considered.

Proteomic Profiling of SGLT-2 Inhibitor Canagliflozin in a Swine Model of Chronic Myocardial Ischemia.

Sodium-glucose cotransporter-2 (SGLT2) inhibitors are known to be cardioprotective independent of glucose control, but the mechanisms of these benefits are unclear. We previously demonstrated improved cardiac function and decreased fibrosis in a swine model of chronic myocardial ischemia. The goal of this study is to use high-sensitivity proteomic analyses to characterize specific molecular pathways affected by SGLT-2 inhibitor canagliflozin (CAN) therapy in a swine model of chronic myocardial ischemia. Chronic myocardial ischemia was induced in sixteen Yorkshire swine via the placement of an ameroid constrictor to the left circumflex coronary artery. After two weeks of recovery, swine received either 300 mg of CAN daily (n = 8) or a control (n = 8). After five weeks of therapy, the group of swine were euthanized, and left ventricular tissue was harvested and sent for proteomic analysis. Total proteomic analysis identified a total of 3256 proteins between the CAN and control groups. Three hundred and five proteins were statistically different. This included 55 proteins that were downregulated (p < 0.05, fold change <0.5) and 250 that were upregulated (p < 0.05, fold change >2) with CAN treatment. Pathway analysis demonstrated the upregulation of several proteins involved in metabolism and redox activity in the CAN-treated group. The CAN group also exhibited a downregulation of proteins involved in motor activity and cytoskeletal structure. In our swine model of chronic myocardial ischemia, CAN therapy alters several proteins involved in critical molecular pathways, including redox regulation and metabolism. These findings provide additional mechanistic insights into the cardioprotective effects of canagliflozin.

DPP-4 inhibitor sitagliptin treatment results in altered myocardial metabolic proteome and oxidative phosphorylation in a swine model of chronic myocardial ischemia.

Small animal models have shown improved cardiac function with DPP-4 inhibition, but many human studies have shown worse outcomes or no benefit. We seek to bridge the gap by studying the DPP-4 inhibitor sitagliptin in a swine model of chronic myocardial ischemia using proteomic analysis. Thirteen Yorkshire swine underwent the placement of an ameroid constrictor on the left coronary circumflex artery to model chronic myocardial ischemia. Two weeks post-op, swine received either sitagliptin 100 mg daily (SIT, n = 5) or no drug (CON, n = 8). After 5 weeks of treatment, swine underwent functional measurements and tissue harvest. In the SIT group compared to CON, there was a trend towards decreased cardiac index (p = 0.06). The non-ischemic and ischemic myocardium had 396 and 166 significantly decreased proteins, respectively, in the SIT group compared to CON (all p < 0.01). This included proteins involved in fatty acid oxidation (FAO), myocardial contraction, and oxidative phosphorylation (OXPHOS). Sitagliptin treatment resulted in a trend towards decreased cardiac index and decreased expression of proteins involved in OXPHOS, FAO, and myocardial contraction in both ischemic and non-ischemic swine myocardium. These metabolic and functional changes may provide some mechanistic evidence for outcomes seen in clinical studies.

Crafting a Rigorous, Clinically Relevant Large Animal Model of Chronic Myocardial Ischemia: What Have We Learned in 20 Years?

The past several decades have borne witness to several breakthroughs and paradigm shifts within the field of cardiovascular medicine, but one component that has remained constant throughout this time is the need for accurate animal models for the refinement and elaboration of the hypotheses and therapies crucial to our capacity to combat human disease. Numerous sophisticated and high-throughput molecular strategies have emerged, including rational drug design and the multi-omics approaches that allow extensive characterization of the host response to disease states and their prospective resolutions, but these technologies all require grounding within a faithful representation of their clinical context. Over this period, our lab has exhaustively tested, progressively refined, and extensively contributed to cardiovascular discovery on the basis of one such faithful representation. It is the purpose of this paper to review our porcine model of chronic myocardial ischemia using ameroid constriction and the subsequent myriad of physiological and molecular-biological insights it has allowed our lab to attain and describe. We hope that, by depicting our methods and the insight they have yielded clearly and completely-drawing for this purpose on comprehensive videographic illustration-other research teams will be empowered to carry our work forward, drawing on our experience to refine their own investigations into the pathogenesis and eradication of cardiovascular disease.

Co-treatment with bone marrow-derived mesenchymal stem cells and curcumin improved angiogenesis in myocardium in a rat model of MI.

The cardioprotective properties of mesenchymal stem cells and the therapeutic potential of curcumin (CUR) have been explored. Combining these approaches may enhance stem cell effectiveness and expedite healing. This study aimed to investigate the synergistic effects of co-treating bone marrow mesenchymal stem cells (BMSCs) with curcumin on vascular endothelial growth factor (VEGF) levels, in a rat model of myocardial ischemia (MI). Sixty-five male rats were divided into four groups: G1 (healthy control), G2 (MI induced by isoproterenol hydrochloride), G3 (treated with BMSCs), and G4 (co-treated with curcumin and BMSCs). Blood and tissue samples were collected at specific time points (day 1, 7, 15 and 21) after MI induction. Serum levels of lactate dehydrogenase (LDH), creatine kinase (CK), cardiac troponin I (cTnI), aspartate aminotransferase (AST), CK-MB and VEGF were measured. VEGF mRNA and protein expression were evaluated using RT-qPCR and Western blot techniques. Histopathological assessments were performed using H&E staining and CD31 immunofluorescence staining. VEGF expression significantly increased on days 7 and 15 in the CUR-BMSCs group, peaking on day 7. Western blot analysis confirmed elevated VEGF protein expression on days 7 and 15 post-MI. ELISA results demonstrated increased serum VEGF levels on days 7 and 15, reaching the highest level on day 7 in CUR-BMSCs-treated animals. Treated groups showed lower levels of LDH, AST, CK, CK-MB and cTnI compared to the untreated MI group. H&E staining revealed improved myocardial structure, increased formation of new capillaries, in both treatment groups compared to the MI group. Combining curcumin with BMSCs promotes angiogenesis in the infarcted myocardium after 15days of MI induction. These findings suggest the potential of this combined therapy approach for enhancing cardiac healing and recovery.

Proteomic Analysis and Sex-Specific Changes in Chronically Ischemic Swine Myocardium Treated with Sodium-Glucose Cotransporter-2 Inhibitor Canagliflozin.

Although sodium-glucose cotransporter-2 inhibitors have been shown to improve cardiovascular outcomes in general, little is presently known about any sex-specific changes that may result from this therapy. We sought to investigate and quantify potential sex-specific changes seen with the sodium-glucose cotransporter-2 inhibitor canagliflozin (CAN) in a swine model of chronic myocardial ischemia. Eighteen Yorkshire swine underwent left thoracotomy with placement of an ameroid constrictor. Two weeks postop, swine were assigned to receive either control (F = 5 and M = 5) or CAN 300 mg daily (F = 4 and M = 4). After 5 weeks of therapy, swine underwent myocardial functional measurements, and myocardial tissue was sent for proteomic analysis. Functional measurements showed increased cardiac output, stroke volume, ejection fraction, and ischemic myocardial flow at rest in male swine treated with CAN compared with control male swine (all p < 0.05). The female swine treated with CAN had no change in cardiac function as compared with control female swine. Proteomic analysis demonstrated 6 upregulated and 97 downregulated proteins in the CAN female group compared with the control female group. Pathway analysis showed decreases in proteins in the tricarboxylic acidic cycle. The CAN male group had 639 upregulated and 172 downregulated proteins compared with control male group. Pathway analysis showed increases in pathways related to cellular metabolism and decreases in pathways relevant to the development of cardiomyopathy and to oxidative phosphorylation. Male swine treated with CAN had significant improvements in cardiac function that were not observed in female swine treated with CAN. Moreover, CAN treatment in male swine was associated with significantly more changes in protein expression than in female swine treated with CAN. The increased proteomic changes seen in the CAN male group likely contributed to the more robust changes in cardiac function seen in male swine treated with CAN.

Intramyocardial Injection of Hypoxia-Conditioned Extracellular Vesicles Modulates Response to Oxidative Stress in the Chronically Ischemic Myocardium.

Patients with advanced coronary artery disease (CAD) who are not eligible for stenting or surgical bypass procedures have limited treatment options. Extracellular vesicles (EVs) have emerged as a potential therapeutic target for the treatment of advanced CAD. These EVs can be conditioned to modify their contents. In our previous research, we demonstrated increased perfusion, decreased inflammation, and reduced apoptosis with intramyocardial injection of hypoxia-conditioned EVs (HEVs). The goal of this study is to further understand the function of HEVs by examining their impact on oxidative stress using our clinically relevant and extensively validated swine model of chronic myocardial ischemia. Fourteen Yorkshire swine underwent a left thoracotomy for the placement of an ameroid constrictor on the left circumflex coronary artery to model chronic myocardial ischemia. After two weeks of recovery, the swine underwent a redo thoracotomy with injection of either HEVs (n = 7) or a saline control (CON, n = 7) into the ischemic myocardium. Five weeks after injection, the swine were subjected to terminal harvest. Protein expression was measured using immunoblotting. OxyBlot analysis and 3-nitrotyrosine staining were used to quantify total oxidative stress. There was a significant increase in myocardial expression of the antioxidants SOD 2, GPX-1, HSF-1, UCP-2, catalase, and HO-1 (all p ≤ 0.05) in the HEV group when compared to control animals. The HEVs also exhibited a significant increase in pro-oxidant NADPH oxidase (NOX) 1, NOX 3, p47phox, and p67phox (all p ≤ 0.05). However, no change was observed in the expression of NFkB, KEAP 1, and PRDX1 (all p > 0.05) between the HEV and CON groups. There were no significant differences in total oxidative stress as determined by OxyBlot and 3-nitrotyrosine staining (p = 0.64, p = 0.32) between the groups. Administration of HEVs in ischemic myocardium induces a significant increase in pro- and antioxidant proteins without a net change in total oxidative stress. These findings suggest that HEV-induced changes in redox signaling pathways may play a role in increased perfusion, decreased inflammation, and reduced apoptosis in ischemic myocardium. Further studies are required to determine if HEVs alter the net oxidative stress in ischemic myocardium at an earlier time point of HEV administration.

Comparative effects of canagliflozin and sitagliptin in chronically ischemic myocardium.

Recent studies demonstrate that sodium-glucose cotransporter 2 inhibitors (SGLT2i) and dipeptidyl peptidase-4 inhibitors (DPP4i), two classes of antidiabetic drugs, are cardioprotective. However, the mechanisms of these benefits and their comparative efficacy remain unclear. We aimed to compare the effects of these antidiabetic agents on cardiac function, perfusion, and microvascular density using a swine model of chronic myocardial ischemia. Chronic myocardial ischemia was induced in Yorkshire swine by ameroid constrictor placement to the left circumflex artery. Two weeks later, pigs were administered vehicle ("CON", 8 pigs), 300 mg SGLT2i canagliflozin, ("CANA", 8 pigs), or 100 mg DPP4i sitagliptin ("SIT", 5 pigs) daily. Five weeks later, pigs were euthanized. Cardiac function, perfusion, collateralization, and protein expression were determined by pressure-volume catheter, microsphere analysis, immunofluorescence, and immunoblotting, respectively. Compared with SIT, CANA was associated with improved stroke volume and cardiac output, with a trend towards reduced left ventricular stiffness. Both CANA and SIT trended towards improved perfusion compared to CON, but there were no differences between the two treatment groups. SIT was associated with improved capillary density with a trend towards improved arteriolar density compared to CANA. Both CANA and SIT were associated with increased expression of vascular endothelial cadherin compared to CON, without differences in treatment groups. SIT pigs had decreased 5' adenosine monophosphate-activated protein kinase activation compared to CON and CANA. There was a trend towards increased endothelial nitric oxide synthase activation in the SIT group compared to CON. There were no differences in activation of extracellular signal-regulated kinase 1/2 across groups. In the setting of chronic myocardial ischemia, canagliflozin is associated with improved cardiac function compared to sitagliptin, with similar effects on perfusion despite differences in microvascular collateralization.