Citric Acid Cycle Metabolites Predict Infarct Size in Pigs Submitted to Transient Coronary Artery Occlusion and Treated with Succinate Dehydrogenase Inhibitors or Remote Ischemic Perconditioning

Succinate dehydrogenase (SDH) inhibition with malonate during reperfusion reduced myocardial infarction in animals, whereas its endogenous substrate, succinate, is detected in plasma from STEMI patients. We investigated whether protection by SDH inhibition is additive to that of remote ischemic perconditioning (RIC) in pigs submitted to transient coronary artery occlusion, and whether protective maneuvers influence plasma levels of citric acid cycle metabolites. Forty pigs were submitted to 40 min coronary occlusion and reperfusion, and allocated to four groups (controls, sodium malonate 10 mmol/L, RIC, and malonate + RIC). Plasma was obtained from femoral and great cardiac veins and analyzed by LC-MS/MS. Malonate, RIC, and malonate + RIC reduced infarct size (24.67 ± 5.98, 25.29 ± 3.92 and 29.83 ± 4.62% vs. 46.47 ± 4.49% in controls, p < 0.05), but no additive effects were detected. Enhanced concentrations of succinate, fumarate, malate and citrate were observed in controls during initial reperfusion in the great cardiac vein, and most were reduced by cardioprotective maneuvers. Concentrations of succinate, fumarate, and malate significantly correlated with infarct size. In conclusion, despite the combination of SDH inhibition during reperfusion and RIC did not result in additive protection, plasma concentrations of selected citric acid cycle metabolites are attenuated by protective maneuvers, correlate with irreversible injury, and might become a prognosis tool in STEMI patients.     

Engineering Biomaterials for Myocardial Regeneration and Repair

Augmentation of myocardial tissue regeneration processes in injured hearts represents a major challenge in cardiology as current therapeutic approaches do not regenerate the myocardial tissue. Herein, we describe three emerging biomaterial-based strategies to treat heart injuries, as stand-alone therapies or in combination with regeneration-inducing signals and/or cells. One strategy relies on the injection of acellular biomaterials, at an early stage after myocardial infarction (MI); these materials replace the damaged extracellular matrix, maintain left ventricular (LV) thickness, and prevent the negative LV remodeling and progression to heart failure. This strategy is currently being investigated in advanced clinical trials using a novel alginate-based biomaterial. The second strategy employs engineered biomaterials, spatially presenting multiple regeneration-inducing factors, to promote myocardial tissue regeneration in chronic infarcted hearts. The recent attempts to understand the “natural capacity” of the myocardium to heal and the factors involved in these processes are promising to advance this therapy. The third strategy applies biomaterials to promote cardiac tissue engineering and create a pre-vascularized cardiac patch to replace damaged or missing myocardial tissue. Collectively, this review emphasizes the increasing importance of biomaterials in cardiology, describes the engineering schemes used in their fabrication, and their implementation in various therapeutic strategies aimed at cardiac tissue regeneration and repair. It mainly highlights the contribution of our group in developing these strategies.     

miR155 Deficiency Reduces Myofibroblast Density but Fails to Improve Cardiac Function after Myocardial Infarction in Dyslipidemic Mouse Model

Myocardial infarction remains the most common cause of heart failure with adverse remodeling. MicroRNA (miR)155 is upregulated following myocardial infarction and represents a relevant regulatory factor for cardiac remodeling by engagement in cardiac inflammation, fibrosis and cardiomyocyte hypertrophy. Here, we investigated the role of miR155 in cardiac remodeling and dysfunction following myocardial infarction in a dyslipidemic mouse model. Myocardial infarction was induced in dyslipidemic apolipoprotein E-deficient (ApoE^−/−) mice with and without additional miR155 knockout by ligation of the LAD. Four weeks later, echocardiography was performed to assess left ventricular (LV) dimensions and function, and mice were subsequently sacrificed for histological analysis. Echocardiography revealed no difference in LV ejection fractions, LV mass and LV volumes between ApoE^−/− and ApoE^−/−/miR155^−/− mice. Histology confirmed comparable infarction size and unaltered neoangiogenesis in the myocardial scar. Notably, myofibroblast density was significantly decreased in ApoE^−/−/miR155^−/− mice compared to the control, but no difference was observed for total collagen deposition. Our findings reveal that genetic depletion of miR155 in a dyslipidemic mouse model of myocardial infarction does not reduce infarction size and consecutive heart failure but does decrease myofibroblast density in the post-ischemic scar.     

Plasma Exosome Profile in ST-Elevation Myocardial Infarction Patients with and without Out-of-Hospital Cardiac Arrest

The identification of new biomarkers allowing an early and more accurate characterization of patients with ST-segment elevation myocardial infarction (STEMI) is still needed, and exosomes represent an attractive diagnostic tool in this context. However, the characterization of their protein cargo in relation to cardiovascular clinical manifestation is still lacking. To this end, 35 STEMI patients (17 experiencing resuscitated out-of-hospital cardiac arrest (OHCA-STEMI) and 18 uncomplicated) and 32 patients with chronic coronary syndrome (CCS) were enrolled. Plasma exosomes were characterized by the nanoparticle tracking analysis and Western blotting. Exosomes from STEMI patients displayed a higher concentration and size and a greater expression of platelet (GPIIb) and vascular endothelial (VE-cadherin) markers, but a similar amount of cardiac troponin compared to CCS. In addition, a difference in exosome expression of acute-phase proteins (ceruloplasmin, transthyretin and fibronectin) between STEMI and CCS patients was found. GPIIb and brain-associated marker PLP1 accurately discriminated between OHCA and uncomplicated STEMI. In conclusion, the exosome profile of STEMI patients has peculiar features that differentiate it from that of CCS patients, reflecting the pathophysiological mechanisms involved in STEMI. Additionally, the exosome expression of brain- and platelet-specific markers might allow the identification of patients experiencing ischemic brain injury in STEMI.     

共济失调毛细血管扩张突变基因缺陷对小鼠心肌梗死后心脏重塑的影响

目的 观察共济失调毛细血管扩张突变基因(ataxia telangiectasia mutated,ATM)单倍体缺陷对小鼠心肌梗死后心脏重塑的影响,并探讨其相关机制.方法 将ATM单倍体基因缺陷小鼠(ATM+/-)和同窝野生型小鼠(ATM+/+)通过结扎冠状动脉左前降支建立心肌梗死模型,同时设立假手术组.术后7 d,...     

Therapeutic Acellular Scaffolds for Limiting Left Ventricular Remodelling-Current Status and Future Directions

Myocardial infarction (MI) is one of the leading causes of heart-related deaths worldwide. Following MI, the hypoxic microenvironment triggers apoptosis, disrupts the extracellular matrix and forms a non-functional scar that leads towards adverse left ventricular (LV) remodelling. If left untreated this eventually leads to heart failure. Besides extensive advancement in medical therapy, complete functional recovery is never accomplished, as the heart possesses limited regenerative ability. In recent decades, the focus has shifted towards tissue engineering and regenerative strategies that provide an attractive option to improve cardiac regeneration, limit adverse LV remodelling and restore function in an infarcted heart. Acellular scaffolds possess attractive features that have made them a promising therapeutic candidate. Their application in infarcted areas has been shown to improve LV remodelling and enhance functional recovery in post-MI hearts. This review will summarise the updates on acellular scaffolds developed and tested in pre-clinical and clinical scenarios in the past five years with a focus on their ability to overcome damage caused by MI. It will also describe how acellular scaffolds alone or in combination with biomolecules have been employed for MI treatment. A better understanding of acellular scaffolds potentialities may guide the development of customised and optimised therapeutic strategies for MI treatment.     

The Expression of Lipoprotein Receptors Is Increased in the Infarcted Area After Myocardial Infarction Induced in Rats With Cardiac Dysfunction

Left ventricular (LV) remodeling after myocardial infarction constitutes the structural basis for ventricular dysfunction and heart failure. The characterization underlying the expression of lipoprotein receptors in cardiac dysfunction is scarcely explored. The aim of this study was to analyze the status of lipoprotein receptors on the infarcted and noninfarcted areas of LV and to verify whether nanoparticles that mimic the lipid structure of low‐density lipoprotein (LDL) and have the ability to bind to LDL receptors (LDE) are taken up more avidly by the noninfarcted LV. 13 male Wistar rats with left coronary artery ligation (myocardial infarction [MI]) and 12 animals with SHAM operation (SHAM) were used in this study. 6 weeks after the procedure, the quantification of low‐density lipoprotein receptor (LDLR), LDL receptor‐related protein 1 (LRP1), scavenger receptor‐class B type I (SR‐BI) lipoprotein receptors, and PCNA proliferation marker, and tissue uptake of radioactively labeled LDE were performed. Immunohistochemistry and Western blot analysis showed that LDLR, LRP1, SR‐BI, and PCNA, expression in infarcted area of MI was remarkably higher than SHAM and noninfarcted subendocardial (SEN) and interstitial (INT) areas. In addition, in SEN noninfarcted area of MI, the presence of LDLR was about threefold higher than in SHAM SEN and INT noninfarcted areas. The LDE uptake of noninfarcted LV of MI group was about 30% greater than that of SHAM group. In conclusion, these findings regarding the status of lipoprotein receptors after MI induction could help to establish mechanisms on myocardial repairing. In conclusion, infarcted rats with LV dysfunction showed increased expression of lipoprotein receptors mainly in the infarcted area.     

Translocator Protein Modulation by 4′-Chlorodiazepam and NO Synthase Inhibition Affect Cardiac Oxidative Stress,Cardiometabolic and Inflammatory Markers in Isoprenaline-Induced Rat Myocardial Infarction

The possible cardioprotective effects of translocator protein (TSPO) modulation with its ligand 4′-Chlorodiazepam (4′-ClDzp) in isoprenaline (ISO)-induced rat myocardial infarction (MI) were evaluated, alone or in the presence of L-NAME. Wistar albino male rats (b.w. 200–250 g, age 6–8 weeks) were divided into 4 groups (10 per group, total number N = 40), and certain substances were applied: 1. ISO 85 mg/kg b.w. (twice), 2. ISO 85 mg/kg b.w. (twice) + L-NAME 50 mg/kg b.w., 3. ISO 85 mg/kg b.w. (twice) + 4′-ClDzp 0.5 mg/kg b.w., 4. ISO 85 mg/kg b.w. (twice) + 4′-ClDzp 0.5 mg/kg b.w. + L-NAME 50 mg/kg b.w. Blood and cardiac tissue were sampled for myocardial injury and other biochemical markers, cardiac oxidative stress, and for histopathological evaluation. The reduction of serum levels of high-sensitive cardiac troponin T hs cTnT and tumor necrosis factor alpha (TNF-α), then significantly decreased levels of serum homocysteine Hcy, urea, and creatinine, and decreased levels of myocardial injury enzymes activities superoxide dismutase (SOD) and glutathione peroxidase (GPx) as well as lower grades of cardiac ischemic changes were demonstrated in ISO-induced MI treated with 4′-ClDzp. It has been detected that co-treatment with 4′-ClDzp + L-NAME changed the number of registered parameters in comparison to 4′-ClDzp group, indicating that NO (nitric oxide) should be important in the effects of 4′-ClDzp.     

Neutrophil Elastase Deficiency Ameliorates Myocardial Injury Post Myocardial Infarction in Mice

Neutrophils are recruited into the heart at an early stage following a myocardial infarction (MI). These secrete several proteases, one of them being neutrophil elastase (NE), which promotes inflammatory responses in several disease models. It has been shown that there is an increase in NE activity in patients with MI; however, the role of NE in MI remains unclear. Therefore, the present study aimed to investigate the role of NE in the pathogenesis of MI in mice. NE expression peaked on day 1 in the infarcted hearts. In addition, NE deficiency improved survival and cardiac function post-MI, limiting fibrosis in the noninfarcted myocardium. Sivelestat, an NE inhibitor, also improved survival and cardiac function post-MI. Flow cytometric analysis showed that the numbers of heart-infiltrating neutrophils and inflammatory macrophages (CD11b⁺F4/80⁺CD206^low cells) were significantly lower in NE-deficient mice than in wild-type (WT) mice. At the border zone between intact and necrotic areas, the number of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive apoptotic cells was lower in NE-deficient mice than in WT mice. Western blot analyses revealed that the expression levels of insulin receptor substrate 1 and phosphorylation of Akt were significantly upregulated in NE-knockout mouse hearts, indicating that NE deficiency might improve cardiac survival by upregulating insulin/Akt signaling post-MI. Thus, NE may enhance myocardial injury by inducing an excessive inflammatory response and suppressing Akt signaling in cardiomyocytes. Inhibition of NE might serve as a novel therapeutic target in the treatment of MI.     

A sequential method for real-time detection of life-threatening signals in serum potassium level after myocardial infarction

Clinical guidelines recommend maintaining potassium levels between 4.0 and 5.0 mEq/L in patients with acute myocardial infarction (MI). These guidelines are based on studies that found associations between crossing of absolute potassium limits and mortality. This article investigates a different approach: we hypothesized that a change in the potassium level may be a harbinger of short survivability, rather than crossing of absolute boundaries. Our objectives were to (1) examine whether a change in the mean potassium level can predict in-hospital death in complicated MI hospitalizations (30 days or more) and (2) formulate a framework for on-line detection of such changes in patients hospitalized with MI. The study included 195 patients who were hospitalized from 2002 to 2014. We found evidence that a change in the mean has the ability to distinguish between survivors and nonsurvivors. A threshold for raising an alarm was specified by plotting a receiver operating characteristic (ROC) curve and choosing the best combination of sensitivity and specificity. The method detected 64% of the patients who eventually died, while wrongly alerting for 25% of the survivors. Almost all of the true alarms were given in a time that would have been reasonable enough to address the cause of the disorder.     

Effects of Heme Oxygenase-1 Upregulation on Blood Pressure and Cardiac Function in an Animal Model of Hypertensive Myocardial Infarction

In this study, we evaluate the effect of HO-1 upregulation on blood pressure and cardiac function in the new model of infarct spontaneous hypertensive rats (ISHR). Male spontaneous hypertensive rats (SHR) at 13 weeks (n = 40) and age-matched male Wistar (WT) rats (n = 20) were divided into six groups: WT (sham + normal saline (NS)), WT (sham + Co(III) Protoporphyrin IX Chloride (CoPP)), SHR (myocardial infarction (MI) + NS), SHR (MI + CoPP), SHR (MI + CoPP + Tin Mesoporphyrin IX Dichloride (SnMP)), SHR (sham + NS); CoPP 4.5 mg/kg, SnMP 15 mg/kg, for six weeks, one/week, i.p., n = 10/group. At the sixth week, echocardiography (UCG) and hemodynamics were performed. Then, blood samples and heart tissue were collected. Copp treatment in the SHR (MI + CoPP) group lowered blood pressure, decreased infarcted area, restored cardiac function (left ventricular ejection fraction (LVEF), left ventricular fraction shortening (LVFS), +dp/dt_max, (−dp/dt_max)/left ventricular systolic pressure (LVSP)), inhibited cardiac hypertrophy and ventricular enlargement (downregulating left ventricular end-systolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD) and heart weight/body weight (HW/BW)), lowered serum CRP, IL-6 and Glu levels and increased serum TB, NO and PGI2 levels. Western blot and immunohistochemistry showed that HO-1 expression was elevated in the SHR (MI + CoPP) group, while co-administration with SnMP suppressed the benefit functions mentioned above. In conclusion, HO-1 upregulation can lower blood pressure and improve post-infarct cardiac function in the ISHR model. These functions may be involved in the inhibition of inflammation and the ventricular remodeling process and in the amelioration of glucose metabolism and endothelial dysfunction.     

The Role of Antioxidation and Immunomodulation in Postnatal Multipotent Stem Cell-Mediated Cardiac Repair

Oxidative stress and inflammation play major roles in the pathogenesis of coronary heart disease including myocardial infarction (MI). The pathological progression following MI is very complex and involves a number of cell populations including cells localized within the heart, as well as cells recruited from the circulation and other tissues that participate in inflammatory and reparative processes. These cells, with their secretory factors, have pleiotropic effects that depend on the stage of inflammation and regeneration. Excessive inflammation leads to enlargement of the infarction site, pathological remodeling and eventually, heart dysfunction. Stem cell therapy represents a unique and innovative approach to ameliorate oxidative stress and inflammation caused by ischemic heart disease. Consequently, it is crucial to understand the crosstalk between stem cells and other cells involved in post-MI cardiac tissue repair, especially immune cells, in order to harness the beneficial effects of the immune response following MI and further improve stem cell-mediated cardiac regeneration. This paper reviews the recent findings on the role of antioxidation and immunomodulation in postnatal multipotent stem cell-mediated cardiac repair following ischemic heart disease, particularly acute MI and focuses specifically on mesenchymal, muscle and blood-vessel-derived stem cells due to their antioxidant and immunomodulatory properties.     

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

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

Factor XIII B Subunit Polymorphisms and the Risk of Coronary Artery Disease

The aim of the case-control study was to explore the effect of coagulation factor XIII (FXIII) B subunit (FXIII-B) polymorphisms on the risk of coronary artery disease, and on FXIII levels. In the study, 687 patients admitted for coronary angiography to investigate suspected coronary artery disease and 994 individuals representing the Hungarian population were enrolled. The patients were classified according to the presence of significant coronary atherosclerosis (CAS) and history of myocardial infarction (MI). The F13B gene was genotyped for p.His95Arg and for intron K nt29756 C>G polymorphisms; the latter results in the replacement of 10 C-terminal amino acids by 25 novel amino acids. The p.His95Arg polymorphism did not influence the risk of CAS or MI. The FXIII-B intron K nt29756 G allele provided significant protection against CAS and MI in patients with a fibrinogen level in the upper tertile. However, this effect prevailed only in the presence of the FXIII-A Leu34 allele, and a synergism between the two polymorphisms was revealed. Carriers of the intron K nt29756 G allele had significantly lower FXIII levels, and FXIII levels in the lower tertile provided significant protection against MI. It is suggested that the protective effect of the combined polymorphisms is related to decreased FXIII levels.     

Exercise Training Alleviates Cardiac Fibrosis through Increasing Fibroblast Growth Factor 21 and Regulating TGF-β1-Smad2/3-MMP2/9 Signaling in Mice with Myocardial Infarction

Exercise training has been reported to alleviate cardiac fibrosis and ameliorate heart dysfunction after myocardial infarction (MI), but the molecular mechanism is still not fully clarified. Fibroblast growth factor 21 (FGF21) exerts a protective effect on the infarcted heart. This study investigates whether exercise training could increase FGF21 protein expression and regulate the transforming growth factor-β1 (TGF-β1)-Smad2/3-MMP2/9 signaling pathway to alleviate cardiac fibrosis following MI. Male wild type (WT) C57BL/6J mice and Fgf21 knockout (Fgf21 KO) mice were used to establish the MI model and subjected to five weeks of different types of exercise training. Both aerobic exercise training (AET) and resistance exercise training (RET) significantly alleviated cardiac dysfunction and fibrosis, up-regulated FGF21 protein expression, inhibited the activation of TGF-β1-Smad2/3-MMP2/9 signaling pathway and collagen production, and meanwhile, enhanced antioxidant capacity and reduced cell apoptosis in the infarcted heart. In contrast, knockout of Fgf21 weakened the cardioprotective effects of AET after MI. In vitro, cardiac fibroblasts (CFs) were isolated from neonatal mice hearts and treated with H₂O₂ (100 μM, 6 h). Recombinant human FGF21 (rhFGF21, 100 ng/mL, 15 h) and/or 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR, 1 mM, 15 h) inhibited H₂O₂-induced activation of the TGF-β1-Smad2/3-MMP2/9 signaling pathway, promoted CFs apoptosis and reduced collagen production. In conclusion, exercise training increases FGF21 protein expression, inactivates the TGF-β1-Smad2/3-MMP2/9 signaling pathway, alleviates cardiac fibrosis, oxidative stress, and cell apoptosis, and finally improves cardiac function in mice with MI. FGF21 plays an important role in the anti-fibrosis effect of exercise training.     

Circulating microRNA-19a as a Potential Novel Biomarker for Diagnosis of Acute Myocardial Infarction

Acute myocardial infarction (AMI) is a serious cardiovascular disease. Investigating new susceptibility genes for effective methods of early diagnosis of AMI is important. In the current study, peripheral blood miR-19a levels were detected by real-time polymerase chain reaction. Significant differences and logistic correlation analyses were carried out by grouping of disease types and stratification of risk factors. Receiver-operator characteristic curve analysis was used to compare the current common clinical biochemical markers and evaluate the sensitivity and specificity of miR-19a for diagnosing AMI. Circulating miR-19a expression in the AMI group was higher than that in controls. The diagnostic effect of circulating miR-19a levels was superior to current clinical biochemical indices, such as CK, CK-MB, MYO, hs-TnI, and BNP. Our results show that there is a close association of circulating miR-19a levels with susceptibility to AMI. Circulating miR-19a levels could be a candidate diagnostic biomarker for AMI.     

Metformin Attenuates Postinfarction Myocardial Fibrosis and Inflammation in Mice

Diabetes is a major risk factor for the development of cardiovascular disease with a higher incidence of myocardial infarction. This study explores the role of metformin, a first-line antihyperglycemic agent, in postinfarction fibrotic and inflammatory remodeling in mice. Three-month-old C57BI/6J mice were submitted to 30 min cardiac ischemia followed by reperfusion for 14 days. Intraperitoneal treatment with metformin (5 mg/kg) was initiated 15 min after the onset of reperfusion and maintained for 14 days. Real-time PCR was used to determine the levels of COL3A1, αSMA, CD68, TNF-α and IL-6. Increased collagen deposition and infiltration of macrophages in heart tissues are associated with upregulation of the inflammation-associated genes in mice after 14 days of reperfusion. Metformin treatment markedly reduced postinfarction fibrotic remodeling and CD68-positive cell population in mice. Moreover, metformin resulted in reduced expression of COL3A1, αSMA and CD68 after 14 days of reperfusion. Taken together, these results open new perspectives for the use of metformin as a drug that counteracts adverse myocardial fibroticand inflammatory remodeling after MI.     

MicroRNAs in Acute ST Elevation Myocardial Infarction—A New Tool for Diagnosis and Prognosis: Therapeutic Implications

Despite diagnostic and therapeutic advances, coronary artery disease and especially its extreme manifestation, ST elevation myocardial infarction (STEMI), remain the leading causes of morbidity and mortality worldwide. Early and prompt diagnosis is of great importance regarding the prognosis of STEMI patients. In recent years, microRNAs (miRNAs) have emerged as promising tools involved in many pathophysiological processes in various fields, including cardiovascular diseases. In acute coronary syndromes (ACS), circulating levels of miRNAs are significantly elevated, as an indicator of cardiac damage, making them a promising marker for early diagnosis of myocardial infarction. They also have prognostic value and great potential as therapeutic targets considering their key function in gene regulation. This review aims to summarize current information about miRNAs and their role as diagnostic, prognostic and therapeutic targets in STEMI patients.