Experimental Model Of Myocardial Infarction Research Articles

Injectable hydrogel-based combination therapy for myocardial infarction: a systematic review and Meta-analysis of preclinical trials

IntroductionThis study evaluates the effectiveness of a combined regimen involving injectable hydrogels for the treatment of experimental myocardial infarction.Patient concernsMyocardial infarction is an acute illness that negatively affects quality of life and increases mortality rates. Experimental models of myocardial infarction can aid in disease research by allowing for the development of therapies that effectively manage disease progression and promote tissue repair.DiagnosisExperimental animal models of myocardial infarction were established using the ligation method on the anterior descending branch of the left coronary artery (LAD).InterventionsThe efficacy of intracardiac injection of hydrogels, combined with cells, drugs, cytokines, extracellular vesicles, or nucleic acid therapies, was evaluated to assess the functional and morphological improvements in the post-infarction heart achieved through the combined hydrogel regimen.OutcomesA literature review was conducted using PubMed, Web of Science, Scopus, and Cochrane databases. A total of 83 papers, including studies on 1332 experimental animals (rats, mice, rabbits, sheep, and pigs), were included in the meta-analysis based on the inclusion and exclusion criteria.The overall effect size observed in the group receiving combined hydrogel therapy, compared to the group receiving hydrogel treatment alone, resulted in an ejection fraction (EF) improvement of 8.87% [95% confidence interval (CI): 7.53, 10.21] and a fractional shortening (FS) improvement of 6.31% [95% CI: 5.94, 6.67] in rat models, while in mice models, the improvements were 16.45% [95% CI: 11.29, 21.61] for EF and 5.68% [95% CI: 5.15, 6.22] for FS.The most significant improvements in EF (rats: MD = 9.63% [95% CI: 4.02, 15.23]; mice: MD = 23.93% [95% CI: 17.52, 30.84]) and FS (rats: MD = 8.55% [95% CI: 2.54, 14.56]; mice: MD = 5.68% [95% CI: 5.15, 6.22]) were observed when extracellular vesicle therapy was used. Although there have been significant results in large animal experiments, the number of studies conducted in this area is limited.ConclusionThe present study demonstrates that combining hydrogel with other therapies effectively improves heart function and morphology. Further preclinical research using large animal models is necessary for additional study and validation.Graphical abstract

In an experimental myocardial infarction model, L-arginine pre-intervention may exert cardioprotective effects by regulating OTULIN levels and mitochondrial dynamics.

The experimental myocardial infarction (MI) model originating from isoproterenol (ISO) is frequently preferred in research due to its similarity to MI-induced damage in humans. Beneficial effects of L-arginine (L-Arg), a semi-essential amino acid, in cardiovascular diseases have been shown in many studies. This study was carried out to determine whether L-Arg pre-intervention has protective effects on heart tissue in the experimental MI model. The 28 rats used in the study were randomly divided into 4 equal groups: control, L-Arg, ISO, and L-Arg+ISO. Upon completion of all applications, cardiac markers in serum and biochemical, histopathological, and immunohistochemical examinations in cardiac tissues were performed. Cardiac markers, histopathological changes, oxidative stress, inflammation, and apoptosis were increased in the experimental MI model. In addition, administration of ISO deregulated OTULIN levels and mitochondrial dynamics in heart tissue. However, L-Arg pre-intervention showed a significant protective effect against changes in ISO-induced MI. L-Arg supplementation with cardioprotective effect may reduce the risks of possible pathophysiological processes in MI.

An Experimental Model of Myocardial Infarction for Studying Cardiac Repair and Remodeling in Knockout Mice.

Cardiovascular disease is the most prevalent cause of death in Western countries, with acute myocardial infarction (MI) being the most prevalent form. This paper describes a protocol for studying the role of galectin 3 (Gal-3) in the temporal evolution of cardiac healing and remodeling in an experimental animal model of MI. The procedures described include an experimental model of MI with a permanent coronary ligature in male C57BL/6J (control) and Gal-3 knockout (KO) mice, an echocardiography procedure to study cardiac remodeling and systolic function in vivo, a histological evaluation of interstitial myocardial fibrosis with picrosirius red-stained and rhodamine-conjugated lectin-stained sections for studying myocyte hypertrophy by the cross-sectional area (MCSA), and the quantification of infarct size and cardiac remodeling (scar thinning, septum thickness, and expansion index) by planimetry in slices stained with Masson's trichrome and triphenyl tetrazolium chloride. Gal-3 KO mice with MI showed disrupted cardiac remodeling and an increase in the scar thinning ratio and the expansion index. At the onset of MI, myocardial function and cardiac remodeling were also severely affected. At 4 weeks post MI, the natural evolution of fibrosis in infarcted Gal-3 KO mice was also affected. In summary, the experimental model of MI is a suitable model for studying the temporal evolution of cardiac repair and remodeling in mice with the genetic deletion of Gal-3 and other animal models. The lack of Gal-3 affects the dynamics of cardiac repair and disrupts the evolution of cardiac remodeling and function after MI.

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.

MRI-based strain measurements reflect morphological changes following myocardial infarction: A study on the UK Biobank cohort.

In a porcine experimental model of myocardial infarction, a localised, layer-specific, circumferential left ventricular strain metric has been shown to indicate chronic changes in ventricular function post-infarction more strongly than ejection fraction. This novel strain metric might therefore provide useful prognostic information clinically. In this study, existing clinical volume indices, global strains, and the novel, layer-specific strain were calculated for a large human cohort to assess variations in ventricular function and morphology with age, sex, and health status. Imaging and health data from the UK Biobank were obtained, including healthy volunteers and those with a history of cardiovascular illness. In total, 710 individuals were analysed and stratified by age, sex and health. Significant differences in all strain metrics were found between healthy and unhealthy populations, as well as between males and females. Significant differences in basal circumferential strain and global circumferential strain were found between healthy males and females, with males having smaller absolute values for both (all 0.001). There were significant differences in the functional variables left ventricular ejection fraction, end-systolic volume, end-systolic volume index and mid-ventricular circumferential strain between healthy and unhealthy male cohorts aged 65-74 (all 0.001). These results suggest that whilst regional circumferential strains may be useful clinically for assessing cardiovascular health, care must be taken to ensure critical values are indexed correctly to age and sex, due to the differences in these values observed here.

The cardiac wound healing response to myocardial infarction.

Myocardial infarction (MI) is defined as evidence of myocardial necrosis consistent with prolonged ischemia. In response to MI, the myocardium undergoes a series of wound healing events that initiate inflammation and shift to anti-inflammation before transitioning to tissue repair that culminates in scar formation to replace the region of the necrotic myocardium. The overall response to MI is determined by two major steps, the first of which is the secretion of proteases by infiltrating leukocytes to breakdown extracellular matrix (ECM) components, a necessary step to remove necrotic cardiomyocytes. The second step is the generation of new ECM that comprises the scar; and this step is governed by the cardiac fibroblasts as the major source of new ECM synthesis. The leukocyte component resides in the middle of the two-step process, contributing to both sides as the leukocytes transition from pro-inflammatory to anti-inflammatory and reparative cell phenotypes. The balance between the two steps determines the final quantity and quality of scar formed, which in turn contributes to chronic outcomes following MI, including the progression to heart failure. This review will summarize our current knowledge regarding the cardiac wound healing response to MI, primarily focused on experimental models of MI in mice. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology Immune System Diseases > Molecular and Cellular Physiology.

S-limonene protects the heart in an experimental model of myocardial infarction induced by isoproterenol: Possible involvement of mitochondrial reactive oxygen species

BackgroundMyocardial infarction (MI) is associated with high mortality rates, despite the fact that there are therapies available. Importantly, excessive oxidative stress may contribute to ischemia/reperfusion injury leading to death related to MI. In this scenario, naturally occurring antioxidant compounds are an important source of possible therapeutic intervention. Thus, this study sought to elucidate the mechanisms of cardioprotection of s-limonene in an isoproterenol-induced MI animal model. MethodsWistar rats were treated with 1 mg/kg s-limonene (SL) or 100 mg/kg N-acetylcysteine (NAC, positive control) once, 30 min after isoproterenol-induced MI (applied in two doses with a 24 h interval). The protective effects of SL in the heart were examined via the serum level of creatine kinase myocardial band (CK-MB), electrocardiographic profile, infarct size and histological parameters. Using isolated cardiomyocytes, we also assessed calcium transient amplitude, cytosolic and mitochondrial oxidative stress and the expression of proteins related to oxidative stress. ResultsSL at a concentration of 1 mg/kg attenuated isoproterenol-induced MI injury, by preventing ST-segment elevation and QTc prolongation in the ECG. SL reduced the infarct size and collagen content in cardiac tissue. At the cellular level, SL prevented increased Ca2+, associated with attenuation of cytosolic and mitochondrial oxidative stress. These changes resulted in a reduction of the oxidized form of Ca2+ Calmodulin-Dependent Kinase II (CaMKII) and restored superoxide dismutase and glutathione peroxidase activity. ConclusionOur data show that s-limonene promotes cardioprotection against MI injury, probably through inhibition of increased Ca2+ and attenuation of oxidative stress via CaMKII.

Homocysteine, Vitamins B6 and Folic Acid in Experimental Models of Myocardial Infarction and Heart Failure-How Strong Is That Link?

Cardiovascular diseases are the leading cause of death and the main cause of disability. In the last decade, homocysteine has been found to be a risk factor or a marker for cardiovascular diseases, including myocardial infarction (MI) and heart failure (HF). There are indications that vitamin B6 plays a significant role in the process of transsulfuration in homocysteine metabolism, specifically, in a part of the reaction in which homocysteine transfers a sulfhydryl group to serine to form α-ketobutyrate and cysteine. Therefore, an elevated homocysteine concentration (hyperhomocysteinemia) could be a consequence of vitamin B6 and/or folate deficiency. Hyperhomocysteinemia in turn could damage the endothelium and the blood vessel wall and induce worsening of atherosclerotic process, having a negative impact on the mechanisms underlying MI and HF, such as oxidative stress, inflammation, and altered function of gasotransmitters. Given the importance of the vitamin B6 in homocysteine metabolism, in this paper, we review its role in reducing oxidative stress and inflammation, influencing the functions of gasotransmitters, and improving vasodilatation and coronary flow in animal models of MI and HF.

Wnt is coming: A role for serum Wnt2 and 4 in fibrotic remodeling following acute myocardial infarction.

Wnt is coming: A role for serum Wnt2 and 4 in fibrotic remodeling following acute myocardial infarction.

Capillarisin Exerts Cardioprotective Effect via Modulating the Matrix Remodelling in an Experimental Model of Myocardial Infarction

Capillarisin is a primary bioactive compound derived from Artemisia capillaris is known to possess antioxidative and anti-inflammatory responses. Although, studies on the protecting effect of capillarisin against heart attack are still not clear. Therefore, in the current investigation, the experimental model of myocardial infarction was induced using isoproterenol in rats. Male Wistar rats were separated into 4 clusters as control, isoproterenol-induced myocardial infarction, capillarisin pretreated (10 mg/kg/d) before isoproterenol induction, capillarisin drug control for 4 w. Finally, infarct size, cardiac markers, such as creatinine kinase, lactate dehydrogenase, matrix proteins and microRNA signatures were revealed by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Rats induced with myocardial infarction demonstrated the abnormality in echocardiographic measurements with increased biomarkers, for example, heart type fatty acid binding protein, creatinine kinase and troponin-I compared to control. While capillarisin pre-treated rats banned myocardial infarction considerably (p<0.001) with restored cardiac functions. Besides, capillarisin pre-treatment repealed the fibrosis onset with restored matrix proteins. In addition, cardiac biomarkers, for example, atrial natriuretic peptide, erythroid transcription factor, nuclear factor of activated T cells were found increased with reduced sarco(endo)plasmic reticulum calcium-ATPase 2 in rats suffering from myocardial infarction. Additionally, the messenger ribonucleic acid of matrix signaling pathways were also found reduced obviously in capillarisin treatment which was disturbed in myocardial infarction induced rats. Capillarisin protected the hearts from failing induced by isoproterenol in rats and provides cardioprotective effect, through restoring the matrix signaling, antiinflammatory, antioxidant effect suggested possible drug candidate for the therapy of heart attack.

Preclinical models of myocardial infarction: from mechanism to translation.

Approximately 7 million people are affected by acute myocardial infarction (MI) each year, and despite significant therapeutic and diagnostic advancements, MI remains a leading cause of mortality worldwide. Preclinical animal models have significantly advanced our understanding of MI and have enabled the development of therapeutic strategies to combat this debilitating disease. Notably, some drugs currently used to treat MI and heart failure (HF) in patients had initially been studied in preclinical animal models. Despite this, preclinical models are limited in their ability to fully reproduce the complexity of MI in humans. The preclinical model must be carefully selected to maximise the translational potential of experimental findings. This review describes current experimental models of MI and considers how they have been used to understand drug mechanisms of action and support translational medicine development. LINKED ARTICLES: This article is part of a themed issue on Preclinical Models for Cardiovascular disease research (BJP 75th Anniversary). To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.5/issuetoc.

Cardioprotective Role of SIRT5 in Response to Acute Ischemia Through a Novel Liver-Cardiac Crosstalk Mechanism.

Protein posttranslational modifications play important roles in cardiovascular diseases. The authors’ previous report showed that the abundance of succinylated and glutarylated proteins was significantly lower in the serum of patients with acute myocardial infarction (AMI) than in that of healthy volunteers, suggesting a potential relationship between protein acylation and AMI. Sirtuin 5 (SIRT5) facilitates the removal of malonyl, succinyl, and glutaryl modification; however, its effects on AMI remain unknown. In this study, the levels of SIRT5 in AMI mouse model was compared. Results showed elevated hepatic SIRT5 after myocardial infarction. Hepatocyte-specific SIRT5 overexpressing mice (liver SIRT5 OE) were generated to address the possible involvement of hepatic SIRT5 in AMI. The areas of myocardial infarction, myocardial fibrosis, and cardiac function in a model of experimental myocardial infarction were compared between liver SIRT5 OE mice and wild-type (WT) mice. The liver SIRT5 OE mice showed a significantly smaller area of myocardial infarction and myocardial fibrosis than the WT mice. The fibroblast growth factor 21 (FGF21) in the blood and myocardium of liver SIRT5 OE mice after AMI was markedly elevated compared with that in WT mice. The results of mass spectrometry showed increased levels of proteins regulating tricarboxylic acid cycle, oxidative phosphorylation, and fatty acid β-oxidation pathways in the liver mitochondria of liver SIRT5 OE mice. These findings showed that SIRT5 may exhibit a cardioprotective effect in response to acute ischemia through a liver-cardiac crosstalk mechanism, probably by increasing the secretion of FGF21 and the improvement of energy metabolism.

Hypoxia - as a Possible Regulator of the Activity of Epicardial Mesothelial Cells After Myocardial Infarction.

Aim To study the effect of hypoxia on the activity of epithelial-mesenchymal transition (EMT) in epicardial cells, which provides formation of a specialized microenvironment.Material and methods This study used a model of experimental myocardial infarction created by ligation of the anterior descendent coronary artery. The activity of epicardial cells after a hypoxic exposure was studied with the hypoxia marker, pimonidazole, bromodeoxyuridine, immunofluorescent staining of heart cryosections, and in vitro mesothelial cell culture.Results The undamaged heart maintained the quiescent condition of mesothelial cells and low levels of their proliferation, extracellular matrix protein production, and of the EMT activity. Acute ischemic injury induced moderate hypoxia in the epicardial/subepicardial region. This caused a global rearrangement of this region due to the initiation of EMT in cells, changes in the cell composition, and accumulation of extracellular matrix proteins. We found that the initiation of EMT in mesothelial cells may result in the formation of smooth muscle cell precursors, fibroblasts, and a population of Sca-1+ cardiac progenitor cells, which may both participate in construction of new blood vessels and serve as a mesenchymal link for the paracrine support of microenvironmental cells. In in vitro experiments, we showed that 72‑h hypoxia facilitated activation of EMT regulatory genes, induced dissembling of intercellular contacts, cell uncoupling, and increased cell plasticity.Conclusion The epicardium of an adult heart serves as a "reparative reserve" that can be reactivated by a hypoxic exposure. This creates a basis for an approach to influence the epicardium to modulate its activity for regulating reparative processes.

The Effect of Mesenchymal Stem Cells Transplantation on Cardiac Functioning and Contractility in Experimental Myocardial Infarction

Introduction. Heart failure as a result of ischemic myocardial remodeling is one of the most severe diseases with poor prognosis. Drug therapy alone with surgical or percutaneous revascularization of damaged myocardium often fails to achieve optimum effect in the treatment of the mentioned syndrome. Cell cardiomyoplasty using autologous bone marrow derived mesenchymal stem cells (BM-MSCs) has already proved to be promising alternative to both these treatment methods, as it’s aimed directly at restoration of normally functioning myocard. The aim. To study the effects of different techniques of cardiomyoplasty with BM-MSCs on morphometrical and functional indices of post-infarctional left ventricular remodeling in experiment. Materials and methods. An experimental model of myocardial infarction in laboratory rats was used for the research. The survived animals were equally divided into 5 groups; the animals of 3 groups underwent BM-MSC transplantation. A certain technique of cardiomyoplasty was used in each of the 3 groups: direct injection into necrotic myocardium, intravenous injection and injection inside left ventricular cavity (which imitates intracoronalintroduction). Other 2 groups were comparison groups where the animals did not achieve BM-MSCs after infarction. There was also control group with intact animals with normal values of all the studied indices. The following invasive and noninvasive measurements of functional heart indices have been done in all research groups: left ventricular weight and its relation to body weight, end-systolic and end-diastolic left ventricular internal dimensions, fractional shortening, ejection fraction, stroke volume, heart rate, systemic arterial pressure and left ventricular inner pressure, both systolic and diastolic. The follow-up period was 1 and 3 months after the experiment. Finally, all animals were euthanized and autopsied, and the results of macroscopic examination of their hearts have been matched with aforecited functional indices in each group. Results and discussion. The analysis of all measured parameters and their comparison between groups have revealed that BM-MSC transplantation (irrespective of technique) conduces to reliably significant retention of functioning myocardium volume, reliably significant improvement of contractility parameters, particularly, reduced end-systolic and end-diastolic internal dimensions, increased ejection fraction, fractional shortening and stroke volume; it also contributes to maximal inalterability of such hemodynamic parameters as heart rate, systemic arterial pressure, left ventricular inner pressure. In addition, in all 3 groups of cell therapy the indices of contractility and pump function of the left ventricle were very close to normal rates. But the optimal results have been obtained in the group of direct intramyocardial injections. Conclusion. Cell cardiomyoplasty with BM-MSCs tends to prevent ischemic myocardial remodeling and, as a result, to improve myocardial contractility and neutralize manifestations of severe heart failure in short-term follow-up of 1 and 3 months.

Antifibrotic effect of novel neutrophil gelatinase-associated lipocalin inhibitors in cardiac and renal disease models

Neutrophil gelatinase-associated lipocalin (NGAL) is involved in cardiovascular and renal diseases. Gene inactivation of NGAL blunts the pathophysiological consequences of cardiovascular and renal damage. We aimed to design chemical NGAL inhibitors and investigate its effects in experimental models of myocardial infarction (MI) and chronic kidney disease induced by 5/6 nephrectomy (CKD) on respectively 8–12 weeks old C57Bl6/j and FVB/N male mice. Among the 32 NGAL inhibitors tested, GPZ614741 and GPZ058225 fully blocked NGAL-induced inflammatory and profibrotic markers in human cardiac fibroblasts and primary mouse kidney fibroblasts. The administration of GPZ614741 (100 mg/kg/day) for three months, was able to improve cardiac function in MI mice and reduced myocardial fibrosis and inflammation. The administration of GPZ614741 (100 mg/kg/day) for two months resulting to no renal function improvement but prevented the increase in blood pressure, renal tubulointerstitial fibrosis and profibrotic marker expression in CKD mice. In conclusion, we have identified new compounds with potent inhibitory activity on NGAL-profibrotic and pro-inflammatory effects. GPZ614741 prevented interstitial fibrosis and dysfunction associated with MI, as well as tubulointerstitial fibrosis in a CKD model. These inhibitors could be used for other diseases that involve NGAL, such as cancer or metabolic diseases, creating new therapeutic options.

Intramyocardial Injection of Plasmid Encoding Platelet Growth Factor Increases Epicardial-Mediated Post Infarction Myocardial Vascularization (Experimental Study)

Increasing incidence of ischemic diseases and limited resources for their treatment stimulate increased interest in studying the mechanisms of vascularization and finding new approaches for its promotion. One of these approaches is gene therapy aimed at activating the epicardium to produce the vascular precursor cells and microenvironment for the «assembly» of de novo vessels. The aim is to investigate the possibility of activating epicardial cells and post infarction cardiac vascularization by injecting a genetic construct encoding PDGFBB. Material and methods . A model of experimental myocardial infarction in a rat with subsequent intramyocardial injection of normal saline solution, control plasmid and plasmid encoding PDGFBB was used. The study of PDGFBB effect on epicardial cell activity was performed on the ex vivo model, as well as in vitro mesothelial cell culture. Results . Post infarction injection of plasmid encoding PDGFBB increases the density of the vascular network in the peri-infarct area as well as migration of pericytes to the injured zone. PDGFBB promotes activation of epicardial cell pool and expression of smooth muscle cell markers in them (shown on the ex vivo model), as well as stimulates activation of epithelial-mesenchymal transition (in vitro). Conclusion . Intramyocardial injection of a genetic construct encoding PDGFBB after an experimental myocardial infarction stimulated vascularization of the peri-infarction zone, which may have been partially due to the activation of the epicardial cell pool.

Implication of anti-angiogenic VEGF-A165b in angiogenesis and systolic function after reperfused myocardial infarction

Abstract Background Angiogenesis participates in re-establishing microcirculation after myocardial infarction (MI). Purpose In this study, we aim to further understand the role of the anti-angiogenic isoform vascular endothelial growth factor (VEGF)-A165b after MI and explore its potential as a co-adjuvant therapy to coronary reperfusion. Methods Two mice MI models were formed: 1) permanent coronary ligation (non-reperfused MI), 2) transient 45-min coronary occlusion followed by reperfusion (reperfused MI); in both models, animals underwent echocardiography before euthanasia at day 21 after MI induction. Serum and myocardial VEGF-A165b levels were determined. In both experimental MI models, functional and structural implication of VEGF-A165b blockade was assessed. In a cohort of 104 ST-segment elevation MI patients, circulating VEGF-A165b levels were correlated with cardiovascular magnetic resonance-derived left ventricular ejection fraction at 6-months and with the occurrence of adverse events (death, heart failure and/or re-infarction). Results In both models, circulating and myocardial VEGF-A165b presence was increased 21 days after MI induction. Serum VEGF-A165b levels inversely correlated with systolic function evaluated by echocardiography. VEGF-A165b blockage increased capillary density, reduced infarct size, and enhanced left ventricular function in reperfused, but not in non-reperfused MI experiments. In patients, higher VEGF-A165b levels correlated with depressed ejection fraction and worse outcomes. Conclusions In experimental and clinical studies, higher serum VEGF-A165b levels associates with a worse systolic function. Its blockage enhances neoangiogenesis, reduces infarct size, and increases ejection fraction in reperfused, but not in non-reperfused MI experiments. Therefore, VEGF-A165b neutralization represents a potential co-adjuvant therapy to coronary reperfusion. Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): This study was funded by “Instituto de Salud Carlos III” and “Fondos Europeos de Desarrollo Regional FEDER” (Exp. PIE15/00013, PI17/01836, PI18/00209 and CIBERCV16/11/00486).

Development and Long-Term Follow-Up of an Experimental Model of Myocardial Infarction in Rabbits.

A chronic model of acute myocardial infarction was developed to study the mechanisms involved in adverse postinfarction ventricular remodeling. In an acute myocardial infarction (AMI), the left circumflex coronary artery of New Zealand White rabbits (n = 9) was occluded by ligature for 1 h, followed by reperfusion. A specific care protocol was applied before, during, and after the intervention, and the results were compared with those of a sham operated group (n = 7). After 5 weeks, programmed stimulation and high-resolution mapping were performed on isolated and perfused hearts using the Langendorff technique. The infarct size determined by 2,3,5-triphenyltetrazolium chloride inside of the area at risk (thioflavin-S) was then determined. The area at risk was similar in both groups (54.33% (experimental infarct group) vs. 58.59% (sham group), ns). The infarct size was 73.16% as a percentage of the risk area. The experimental infarct group had a higher inducibility of ventricular arrhythmias (100% vs. 43% in the sham group, p = 0.009). A reproducible chronic experimental model of myocardial infarction is presented in which the extent and characteristics of the lesions enable the study of the vulnerability to develop ventricular arrhythmias because of the remodeling process that occurs during cardiac tissue repair.

Mzb1 protects against myocardial infarction injury in mice via modulating mitochondrial function and alleviating inflammation.

Myocardial infarction (MI) leads to the loss of cardiomyocytes, left ventricle dilation and cardiac dysfunction, eventually developing into heart failure. Mzb1 (Marginal zone B and B1 cell specific protein 1) is a B-cell-specific and endoplasmic reticulum-localized protein. Mzb1 is an inflammation-associated factor that participates a series of inflammatory processes, including chronic periodontitis and several cancers. In this study we investigated the role of Mzb1 in experimental models of MI. MI was induced in mice by ligation of the left descending anterior coronary artery, and in neonatal mouse ventricular cardiomyocytes (NMVCs) by H2O2 treatment in vitro. We showed that Mzb1 expression was markedly reduced in the border zone of the infarct myocardium of MI mice and in H2O2-treated NMVCs. In H2O2-treated cardiomyocytes, knockdown of Mzb1 decreased mitochondrial membrane potential, impaired mitochondrial function and promoted apoptosis. On contrary, overexpression of Mzb1 improved mitochondrial membrane potential, ATP levels and mitochondrial oxygen consumption rate (OCR), and inhibited apoptosis. Direct injection of lentiviral vector carrying Len-Mzb1 into the myocardial tissue significantly improved cardiac function and alleviated apoptosis in MI mice. We showed that Mzb1 overexpression significantly decreased the levels of Bax/Bcl-2 and cytochrome c and improved mitochondrial function in MI mice via activating the AMPK-PGC1α pathway. In addition, we demonstrated that Mzb1 recruited the macrophages and alleviated inflammation in MI mice. We conclude that Mzb1 is a crucial regulator of cardiomyocytes after MI by improving mitochondrial function and reducinginflammatory signaling pathways, implying a promising therapeutic target in ischemic cardiomyopathy.

Implicación de la isoforma antiangiogénica VEGF-A165b en la angiogénesis y la función sistólica tras un infarto de miocardio reperfundido

Introduction and objectivesAngiogenesis helps to reestablish microcirculation after myocardial infarction (MI). In this study, we aimed to further understand the role of the antiangiogenic isoform vascular endothelial growth factor (VEGF)-A165b after MI and to explore its potential as a coadjuvant therapy to coronary reperfusion. MethodsTwo mice MI models were formed: a) permanent coronary ligation (nonreperfused MI); b) transient 45-minute coronary occlusion followed by reperfusion (reperfused MI); in both models, animals underwent echocardiography before euthanasia at day 21 after MI induction. We determined serum and myocardial VEGF-A165b levels. In both experimental MI models, we assessed the functional and structural role of VEGF-A165b blockade. In a cohort of 104 ST-segment elevation MI patients, circulating VEGF-A165b levels were correlated with cardiovascular magnetic resonance-derived left ventricular ejection fraction at 6 months and with the occurrence of adverse events (death, heart failure, and/or reinfarction). ResultsIn both models, circulating and myocardial VEGF-A165b levels were increased 21 days after MI induction. Serum VEGF-A165b levels inversely correlated with systolic function evaluated by echocardiography. VEGF-A165b blockade increased capillary density, reduced infarct size, and enhanced left ventricular function in reperfused, but not in nonreperfused, MI experiments. In patients, higher VEGF-A165b levels correlated with depressed ejection fraction and worse outcomes. ConclusionsIn experimental and clinical studies, higher serum VEGF-A165b levels are associated with worse systolic function. Their blockade enhances neoangiogenesis, reduces infarct size, and increases ejection fraction in reperfused, but not in nonreperfused, MI experiments. Therefore, VEGF-A165b neutralization represents a potential coadjuvant therapy to coronary reperfusion.