The incidence of acute myocardial infarction (AMI) is increasing yearly. With the use of thrombolysis or percutaneous coronary intervention (PCI), the mortality rate of acute myocardial infarction has been significantly reduced. However, reperfusion can cause additional myocardial injury. There is still a lack of effective drugs to treat I/R injury, and it is urgent to find new therapeutic drugs.

Cardiovascular diseases (CVDs) are at a badly high-risk of morbidity and mortality in the world.

To investigate effects of Ziziphora clinopodioides Lam. flavonoids on ischemia-reperfusion injury of myocardial cells. After application of 6.25, 25, and 100 μg/mL Ziziphora clinopodioides Lam. flavonoids to H9C2 myocardial cells for 24H, they were treated for 4 hours with hydrogen peroxide to induce oxidative damage, whereas controls were cells without treatment and cells only incubated with hydrogen peroxide. Cell viability, lactate dehydrogenase release and mitochondrial membrane potential, intracellular Na+/K+-ATPase activity and ATP content, and reactive oxygen species formation were monitored. An ischemia-reperfusion injury rat model was established by left anterior descending coronary artery ligature in 48 Sprague-Dawley rats, which were divided into positive control with isosorbide mononitrate (10 mg/kg) injection (n=8), model (ischemia-reperfusion, n=8), sham-operated (n=8), and Ziziphora clinopodioides Lam. flavonoids low (75 mg/kg, n=8), medium (150 mg/kg, n=8), and high concentration (300 mg/kg, n=8) groups. Superoxide dismutase activity and malondialdehyde content in homogenized hearts were measured and ischemic and infarction areas were triphenyl tetrazolium chloride and H&E stained for pathological and morphological examinations. Ziziphora clinopodioides Lam. flavonoids preconditioning improved cell viability (P<0.01), intracellular Na/K ATPase activity (P<0.001), and intracellular ATP content (P<0.001) and maintained mitochondrial membrane potential (P<0.05) in hydrogen peroxide treated H9C2 cells as well as rescued superoxide dismutase activity (P<0.01), decreased the malondialdehyde content (P<0.001), and reduced myocardial damage in the ischemia-reperfusion rat model (P<0.001) compared to the controls. Ziziphora clinopodioides Lam. flavonoids may be an effective drug for protecting myocardial tissue from ischemia-reperfusion injury by reducing reactive oxygen species related damage.

Glycine is a well-documented cytoprotective agent. However, whether it has a protective effect against myocardial ischemia-reperfusion injury in vivo is still unknown. By using an open-chest anesthetized rat model, we found that glycine reduced the infarct size by 21% in ischemia-reperfusion injury rats compared with that in the vehicle-treated MI/R rats. The left ventricular ejection fraction and fractional shortening were increased by 19.11% and 30.98%, respectively, in glycine-treated rats. The plasma creatine kinase levels in ischemia-reperfusion injury rats decreased following glycine treatment. Importantly, administration of glycine significantly inhibited apoptosis in post-ischemia-reperfusion myocardium, which was accompanied by suppression of phosphorylated p38 mitogen-activated protein kinase and c-Jun NH2-terminal kinase, as well as the Fas ligand. These results suggest that glycine attenuates myocardial ischemia-reperfusion injury in vivo by inhibiting cardiomyocytes apoptosis.

Restoration of coronary blood flow after a heart attack can cause reperfusion injury potentially leading to impaired cardiac function, adverse tissue remodeling and heart failure. Iron is an essential biometal that may have a pathologic role in this process. There is a clinical need for a precise noninvasive method to detect iron for risk stratification of patients and therapy evaluation. Here, we report that magnetic susceptibility imaging in a large animal model shows an infarct paramagnetic shift associated with duration of coronary artery occlusion and the presence of iron. Iron validation techniques used include histology, immunohistochemistry, spectrometry and spectroscopy. Further mRNA analysis shows upregulation of ferritin and heme oxygenase. While conventional imaging corroborates the findings of iron deposition, magnetic susceptibility imaging has improved sensitivity to iron and mitigates confounding factors such as edema and fibrosis. Myocardial infarction patients receiving reperfusion therapy show magnetic susceptibility changes associated with hypokinetic myocardial wall motion and microvascular obstruction, demonstrating potential for clinical translation.

The aim of this study was to investigate the effects of chrysin (CH) on myocardial ischemia-reperfusion injury. Cytokines were reduced by CH in coronary artery occlusion-induced rats and also in H9C2 cells. The ST segment was also restored by CH. Triphenyltetrazolium chloride (TTC) staining and pathological analysis showed that CH could alleviate myocardial injury. Results in H9C2 cells showed that CH improved heart injury in hypoxia/reoxygenation (H/R) of H9C2 cells. In addition, the expressions of the HMGB1-related inflammation pathway in rats and H9C2 cells were significantly decreased by CH. The present study shows the protective effects of CH on myocardial injury via inflammation.

Therapeutic lymphangiogenesis is a new treatment for cardiovascular diseases. Our previous study showed M2b macrophages can alleviate myocardial ischaemia/reperfusion injury (MI/RI). However, the relation between M2b macrophages and lymphangiogenesis is not clear.

Animal studies have demonstrated beneficial effects of therapeutic hypothermia on myocardial function, yet exact mechanisms remain unclear. Impaired autophagy leads to heart failure and mitophagy is important for mitigating ischemia/reperfusion injury. This study aims to investigate whether the beneficial effects of therapeutic hypothermia are due to preserved autophagy and mitophagy. Under general anesthesia, the left anterior descending coronary artery of 19 female farm pigs was occluded for 90 minutes with consecutive reperfusion. 30 minutes after reperfusion, we performed pericardial irrigation with warm or cold saline for 60 minutes. Myocardial tissue analysis was performed one and four weeks after infarction. Therapeutic hypothermia induced a significant increase in autophagic flux, mitophagy, mitochondrial mass and function in the myocardium after infarction. Cell stress, apoptosis, inflammation as well as fibrosis were reduced, with significant preservation of systolic and diastolic function four weeks post infarction. We found similar biochemical changes in human samples undergoing open chest surgery under hypothermic conditions when compared to the warm. These results suggest that autophagic flux and mitophagy are important mechanisms implicated in cardiomyocyte recovery after myocardial infarction under hypothermic conditions. New therapeutic strategies targeting these pathways directly could lead to improvements in prevention of heart failure.

This project is aimed at investigating whether CircANXA2 can promote the apoptosis of myocardial cells by inhibiting miR-133 expression and thereby participate in the development of myocardial ischemia-reperfusion injury. Materials and Method. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression level of CircANXA2 in H9c2 cells after hypoxia/reoxygenation (H/R) treatment. Evaluation of myocardial injury markers in H9c2 cells was performed using commercial kits, including lactate dehydrogenase (LDH), malonaldehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidation (GSH-PX). MTT analysis and flow cytometry were used to detect myocardial cell proliferation and apoptosis, respectively. Western blot was used to detect the protein expression of apoptosis-related genes.

Myocardial injury may be caused by myocardial ischemia-reperfusion (IR), and salvaging such an injury is still a great challenge in clinical practice. This study comprehensively characterized the physiopathologic changes of myocardial injury after IR to explore the underlying mechanism in the early reperfusion phase with particular emphasis on early myocardial inflammation.

The inflammatory cascade and cell death post-myocardial ischemia reperfusion (MI/R) are very complex. Despite the understanding that macrophage inflammation has a pivotal role in the pathophysiology of MI/R, the contribution of macrophage inflammatory signals in tailoring the function of vascular endothelium remains unknown.

The potential cardioprotective effects of the novel vaccine peptide GV1001 were evaluated in myocardial ischemia‑reperfusion injury induced rat models. GV1001 is a human telomerase reverse transcriptase derived peptide, which has been reported to possess both anti‑tumor and anti‑inflammatory effects. The normal saline (control group) and various concentrations (0.001‑10 mg/kg) of GV1001 were administered directly to the right ventricle anterior wall before induction of ischemia. The was induced by Tightening the snare around the left anterior descending coronary artery for 40 min, before releasing the snare for 10 min induced the myocardial ischemia‑reperfusion injury and was conducted in Sprague‑Dawley rats. The area at risk, histology, apoptotic cells, neutrophils and inflammatory cytokines were analyzed from the excised heart tissue following myocardial ischemia‑reperfusion injury. The area at risk was protected by concentrations of GV1001 equal to or higher than 0.01 mg/kg. At 0.1 mg/kg and higher concentrations of GV1001, the hemorrhage in the heart was attenuated, while severe congestion was reported in the control group. Apoptotic cells, myeloperoxidase activity and inflammatory cytokines [tumor necrosis factor (TNF)‑α and interleukin (IL)‑6] revealed decreased levels in a dose‑dependent manner with respect to GV1001 concentration. The group treated with 10 mg/kg GV1001 demonstrated 59.73% apoptotic cells (P<0.001), 48.14% neutrophil contents (P<0.001), 55.63% TNF‑α (P<0.01) and 42.35% IL‑6 (P<0.01) levels, compared with the control group. The novel vaccine peptide GV1001 provided protective effects on myocardial ischemia‑reperfusion injury and, therefore, it should be considered as an alternative potential anti‑inflammatory agent for myocardial ischemia‑reperfusion injury.

Histone deacetylases (HDACs) play a critical role in modulating myocardial protection and cardiomyocyte survivals. However, Specific HDAC isoforms in mediating myocardial ischemia/reperfusion injury remain currently unknown. We used cardiomyocyte-specific overexpression of active HDAC4 to determine the functional role of activated HDAC4 in regulating myocardial ischemia and reperfusion in isovolumetric perfused hearts.

Timely restoration of blood supply following myocardial infarction is critical to save the infarcted myocardium, while reperfusion would cause additional damage. Strontium ions have been shown to promote angiogenesis, but it is unknown whether they can save the damaged myocardium. We report that myocardial ischemia/reperfusion (I/R)-induced functional deterioration and scar formation were notably attenuated by injection of strontium ion-containing composite hydrogels into murine infarcted myocardium at 20 minutes of reperfusion following 60 minutes of ischemia. These beneficial effects were accompanied by reduced cardiomyocyte apoptosis and increased angiogenesis. The effects of strontium ions were further confirmed by the enhanced viability of cardiomyocytes and stimulated angiogenesis in vitro. These findings are the first to reveal the cardioprotective effects of strontium ions against I/R injury, which may provide a new therapeutic approach to ischemic heart disease at a lower cost, with higher stability, and with potentially greater safety.

The underlying mechanism of the myocardial protective effect of fisetin was studied in a rat ischemia/reperfusion injury model. Sprague-Dawley rats were randomly assigned to seven groups and pretreated with different solutions by gavage administration. A rat model of cardiac ischemia/reperfusion injury was established. Plasma levels of Von Willebrand factor (vWF) were determined by ELISA, flow cytometry was used to determine the level of cardiomyocyte apoptosis and 2,3,5-triphenyltetrazolium staining was used to determine the size of myocardial infarcts. Hematoxylin and eosin-stained sections of myocardial tissues were examined for pathological changes. Expressions of nuclear factor (NF)-κB and matrix metallopeptidase 9 (MMP-9) were measured by immunohistochemistry. Compared with the model group, rats pretreated with fisetin, quercetin and aspirin showed significant prolongation of clotting time, prothrombin time, thrombin time and activated partial thromboplastin time. Fisetin treatment better maintained the integrity of myocardial fibers and nuclear integrity, reduced the percentage of apoptotic myocardial cells, inhibited expression of NF-κB, decreased the loss of MMP-9 and reduced nuclear translocation of NF-kB. Rats pretreated with fisetin also demonstrated a significant decrease in plasma levels of vWF. In addition, the protective effect of fisetin on myocardial cells was found to be dose dependent.

The role of prolylcarboxypeptidase (PRCP) in myocardial ischemia/reperfusion (I/R) injury is unclear. Herein, we aimed to evaluate the protective effect of the PRCP-angiotensin-(1-7) [Ang-(1-7)]/bradykinin-(1-9) [BK-(1-9)] axis on myocardial I/R injury and identify the mechanisms involved. Plasma PRCP level and activity, as well as Ang-(1-7) and BK-(1-9) levels, were compared in healthy subjects, patients with unstable angina, and those with ST-segment-elevated acute myocardial infarction (AMI). Thereafter, the effects of PRCP overexpression and knockdown on left ventricular function, mitophagy, and levels of Ang-(1-7) and BK-(1-9) were examined in rats during myocardial I/R. Finally, the effects of Ang-(1-7) and BK-(1-9) on I/R-induced mitophagy and the signaling pathways involved were investigated in vitro in rat cardiomyocytes. AMI patients showed increased plasma level and activity of PRCP and levels of Ang-(1-7) and BK-(1-9) as compared with healthy subjects and those with unstable angina. PRCP protected against myocardial I/R injury in rats by paradoxical regulation of cardiomyocyte mitophagy during the ischemia and reperfusion phases, which was mediated by downstream Ang-(1-7) and BK-(1-9). We further depicted a possible role of activation of AMPK in mitophagy induction during ischemia and activation of Akt in mitophagy inhibition during reperfusion in the beneficial effects of Ang-(1-7) and BK-(1-9). Thus, the PRCP-Ang-(1-7)/BK-(1-9) axis may protect against myocardial I/R injury by paradoxical regulation of cardiomyocyte mitophagy during ischemia and reperfusion phases.

Gasdermin D (GSDMD) plays an essential role in the pathway of pyroptosis. However, whether GSDMD participates in myocardial ischaemia/reperfusion injury (MI/RI) remains poorly understood.

Increased adenosine helps limit infarct size in ischaemia/reperfusion-injured hearts. In cardiomyocytes, 90% of adenosine is catalysed by adenosine kinase (ADK) and ADK inhibition leads to higher concentrations of both intracellular adenosine and extracellular adenosine. However, the role of ADK inhibition in myocardial ischaemia/reperfusion (I/R) injury remains less obvious. We explored the role of ADK inhibition in myocardial I/R injury using mouse left anterior ligation model. To inhibit ADK, the inhibitor ABT-702 was intraperitoneally injected or AAV9 (adeno-associated virus)-ADK-shRNA was introduced via tail vein injection. H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to elucidate the underlying mechanisms. ADK was transiently increased after myocardial I/R injury. Pharmacological or genetic ADK inhibition reduced infarct size, improved cardiac function and prevented cell apoptosis and necroptosis in I/R-injured mouse hearts. In vitro, ADK inhibition also prevented cell apoptosis and cell necroptosis in H/R-treated H9c2 cells. Cleaved caspase-9, cleaved caspase-8, cleaved caspase-3, MLKL and the phosphorylation of MLKL and CaMKII were decreased by ADK inhibition in reperfusion-injured cardiomyocytes. X-linked inhibitor of apoptosis protein (XIAP), which is phosphorylated and stabilized via the adenosine receptors A2B and A1/Akt pathways, should play a central role in the effects of ADK inhibition on cell apoptosis and necroptosis. These data suggest that ADK plays an important role in myocardial I/R injury by regulating cell apoptosis and necroptosis.

To investigate the role of leptin in regulating cell inflammation and protecting myocardium after myocardial ischemia-reperfusion injury in rats through signaling pathway at tissue and molecular protein levels.

Human ESC-derived mesenchymal stem cell (MSC)-conditioned medium (CM) was previously shown to mediate cardioprotection during myocardial ischemia/reperfusion injury through large complexes of 50-100 nm. Here we show that these MSCs secreted 50- to 100-nm particles. These particles could be visualized by electron microscopy and were shown to be phospholipid vesicles consisting of cholesterol, sphingomyelin, and phosphatidylcholine. They contained coimmunoprecipitating exosome-associated proteins, e.g., CD81, CD9, and Alix. These particles were purified as a homogeneous population of particles with a hydrodynamic radius of 55-65 nm by size-exclusion fractionation on a HPLC. Together these observations indicated that these particles are exosomes. These purified exosomes reduced infarct size in a mouse model of myocardial ischemia/reperfusion injury. Therefore, MSC mediated its cardioprotective paracrine effect by secreting exosomes. This novel role of exosomes highlights a new perspective into intercellular mediation of tissue injury and repair, and engenders novel approaches to the development of biologics for tissue repair.