Experimental Acute Myocardial Infarction Research Articles

Effect of Intramyocardial Administration of Baculovirus Encoding the Transcription Factor Tbx20 in Sheep With Experimental Acute Myocardial Infarction.

Gene therapy has been proposed as a strategy to induce cardiac regeneration following acute myocardial infarction (AMI). Given that Tbx20, a transcription factor of the T-box subfamily, stimulates cell proliferation and angiogenesis, we designed a baculovirus overexpressing Tbx20 (Bv-Tbx20) and evaluated its effects in cultured cardiomyocytes and in an ovine model of AMI. Cell proliferation and angiogenesis were measured in cardiomyocytes transduced with Bv-Tbx20 or Bv-Null (control). Subsequently, in sheep with AMI, Bv-Tbx20 or Bv-Null was injected in the infarct border. Cardiomyocyte cell cycle activity, angioarteriogenesis, left ventricular function, and infarct size were assessed. Cardiomyocytes transduced with BvTbx20 increased cell proliferation, cell cycle regulatory and angiogenic gene expression, and tubulogenesis. At 7 days posttreatment, sheep treated with Bv-Tbx20 showed increased Tbx20, promitotic and angiogenic gene expression, decreased levels of P21, increased Ki67- (17.09±5.73 versus 7.77±7.24 cardiomyocytes/mm2, P<0.05) and PHH3 (phospho-histone H3)-labeled cardiomyocytes (10.10±3.51 versus 5.23±2.87 cardiomyocytes/mm2, P<0.05), and increased capillary (2302.68±353.58 versus 1694.52±211.36 capillaries/mm2, P<0.001) and arteriolar (146.95±53.14 versus 84.06±16.84 arterioles/mm2, P<0.05) densities. At 30 days, Bv-Tbx20 decreased infarct size (9.89±1.92% versus 12.62±1.33%, P<0.05) and slightly improved left ventricular function. Baculoviral gene transfer-mediated Tbx20 overexpression exerted angiogenic and cardiomyogenic effects invitro. In sheep with AMI, Bv-Tbx20 induced angioarteriogenesis, cardiomyocyte cell cycle activity, infarct size limitation, and a slight recovery of left ventricular function, suggesting that Bv-Tbx20 gene therapy may contribute to cardiac regeneration following AMI.

Leveraging a neutrophil-derived PCD signature to predict and stratify patients with acute myocardial infarction: from AI prediction to biological interpretation

BackgroundProgrammed cell death (PCD) has recently been implicated in modulating the removal of neutrophils recruited in acute myocardial infarction (AMI). Nonetheless, the clinical significance and biological mechanism of neutrophil-related PCD remain unexplored.MethodsWe employed an integrative machine learning-based computational framework to generate a predictive neutrophil-derived PCD signature (NPCDS) within five independent microarray cohorts from the peripheral blood of AMI patients. Non-negative matrix factorization was leveraged to develop an NPCDS-based AMI subtype. To elucidate the biological mechanism underlying NPCDS, we implemented single-cell transcriptomics on Cd45+ cells isolated from the murine heart of experimental AMI. We finally conducted a Mendelian randomization (MR) study and molecular docking to investigate the therapeutic value of NPCDS on AMI.ResultsWe reported the robust and superior performance of NPCDS in AMI prediction, which contributed to an optimal combination of random forest and stepwise regression fitted on nine neutrophil-related PCD genes (MDM2, PTK2B, MYH9, IVNS1ABP, MAPK14, GNS, MYD88, TLR2, CFLAR). Two divergent NPCDS-based subtypes of AMI were revealed, in which subtype 1 was characterized as inflammation-activated with more vibrant neutrophil activities, whereas subtype 2 demonstrated the opposite. Mechanically, we unveiled the expression dynamics of NPCDS to regulate neutrophil transformation from a pro-inflammatory phase to an anti-inflammatory phase in AMI. We uncovered a significant causal association between genetic predisposition towards MDM2 expression and the risk of AMI. We also found that lidoflazine, isotetrandrine, and cepharanthine could stably target MDM2.ConclusionAltogether, NPCDS offers significant implications for prediction, stratification, and therapeutic management for AMI.

Human-umbilical cord matrix mesenchymal cells improved left ventricular contractility independently of infarct size in swine myocardial infarction with reperfusion.

Human umbilical cord matrix-mesenchymal stromal cells (hUCM-MSC) have demonstrated beneficial effects in experimental acute myocardial infarction (AMI). Reperfusion injury hampers myocardial recovery in a clinical setting and its management is an unmet need. We investigated the efficacy of intracoronary (IC) delivery of xenogeneic hUCM-MSC as reperfusion-adjuvant therapy in a translational model of AMI in swine. In a placebo-controlled trial, pot-belied pigs were randomly assigned to a sham-control group (vehicle-injection; n = 8), AMI + vehicle (n = 12) or AMI + IC-injection (n = 11) of 5 × 105 hUCM-MSC/Kg, within 30 min of reperfusion. AMI was created percutaneously by balloon occlusion of the mid-LAD. Left-ventricular function was blindly evaluated at 8-weeks by invasive pressure-volume loop analysis (primary endpoint). Mechanistic readouts included histology, strength-length relationship in skinned cardiomyocytes and gene expression analysis by RNA-sequencing. As compared to vehicle, hUCM-MSC enhanced systolic function as shown by higher ejection fraction (65 ± 6% vs. 43 ± 4%; p = 0.0048), cardiac index (4.1 ± 0.4 vs. 3.1 ± 0.2 L/min/m2; p = 0.0378), preload recruitable stroke work (75 ± 13 vs. 36 ± 4 mmHg; p = 0.0256) and end-systolic elastance (2.8 ± 0.7 vs. 2.1 ± 0.4 mmHg*m2/ml; p = 0.0663). Infarct size was non-significantly lower in cell-treated animals (13.7 ± 2.2% vs. 15.9 ± 2.7%; Δ = -2.2%; p = 0.23), as was interstitial fibrosis and cardiomyocyte hypertrophy in the remote myocardium. Sarcomere active tension improved, and genes related to extracellular matrix remodelling (including MMP9, TIMP1 and PAI1), collagen fibril organization and glycosaminoglycan biosynthesis were downregulated in animals treated with hUCM-MSC. Intracoronary transfer of xenogeneic hUCM-MSC shortly after reperfusion improved left-ventricular systolic function, which could not be explained by the observed extent of infarct size reduction alone. Combined contributions of favourable modification of myocardial interstitial fibrosis, matrix remodelling and enhanced cardiomyocyte contractility in the remote myocardium may provide mechanistic insight for the biological effect.

Abstract 10581: Sustained Increase of Serum Glial Fibrillary Acidic Protein After First St-Elevation Myocardial Infarction

Introduction: Acute ischemic cardiac injury predisposes for cognitive impairment, dementia and depression. Beyond altered cerebral blood flow and neurohumoral activation, recent positron emission tomography data pathophysiologically suggest acute and chronic neuroinflammation, which is accompanied by astroglial activation, after acute experimental myocardial infarction (MI). Hypothesis: Peripheral serum biomarkers indicating neuronal and glial involvement are altered in the year after first acute MI. Methods: Within the investigator-initiated, prospective, multicenter diagnostic ETiCS study, we quantified serum levels of neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) using ultra-sensitive molecular immunoassays serially in the year after first ST-elevation MI (STEMI). Cardiac magnetic resonance imaging enabled precise detection of infarction volume and ejection fraction. Results: Sufficient biomaterial was available from 45 STEMI patients (aged 28 to 78 years, median 56 years, 11% female). Median serum NfL (quartiles) at hospital admission was 10.6 (7.2, 14.8 pg/ml) and median GFAP 63.8 (47.0, 89.9 pg/ml). Absolute levels of NfL (ρ=0.78; p&lt;0.001) and GFAP (ρ=0.56; p&lt;0.001) correlated to patient age at all time-points. While NfL remained unaltered in the course of one year, GFAP after STEMI increased in the first 3 months after MI with a mean change of +10.6±25.0 pg/ml (p=0.007), and remained elevated after 6 months (+12.4±32.9 pg/ml; p=0.015) and 12 months (+12.6±31.2 pg/ml; p=0.010) compared to baseline. Larger relative infarction volume (ρ=0.41; p=0.009) and higher peak creatine kinase levels (ρ=0.39; p&lt;0.001), but not ejection fraction, correlated to increases of GFAP and NfL, respectively. Conclusions: Our findings suggest subtle glial damage after STEMI which correlates to infarction volume. Further studies need to evaluate the valence of serum GFAP as a peripheral biomarker of cognitive decline after MI.

Abstract 13324: Impact of Chronic Electronic Cigarette Vapor Exposure on the Recovery of Cardiovascular Function in Experimental Rat Myocardial Ischemia/Reperfusion Model

Background: The impact of long-term electronic cigarettes (E-cig) vaping on cardiovascular function in rats were investigated. Methods: Sprague Dawley rats (both sex, 6 weeks old) were randomly exposed to filtered air (n=32), E-cig with nicotine (E-cig Nic + , n=26), E-cig without nicotine (E-cig Nic - , n=26), or standard cigarette smoke (n=31). After exposure to inhalation exposure for 8 weeks, the rats were subjected to 30 minutes of left coronary artery occlusion followed by 3 hours of reperfusion. Cardiovascular function was measured with intracavitary Millar catheters and echocardiography during the surgical procedure. Results: As the data shown in the Table, at 2.5 hours after coronary artery reperfusion, heart rate, cardiac output and positive/negative LV dp/dt were lower in the E-cig Nic + group compared to the air and/or cigarette group. LVFS in the cigarette group was higher than compared to E-cig Nic + or air group. There was a significantly higher systemic arterial resistance in the E-cig Nic + group compared to the cigarette group. Conclusions: Chronic E-cig Nic + exposure impairs the cardiovascular function recovery during the phase of coronary artery reperfusion after heart attack, indicated by reductions of heart rate, cardiac output, LV positive and negative dp/dt (suggesting a reduction in contractility and relaxation); and increase in systemic arterial resistance in the setting of experimental acute myocardial infarction compared to air and/or standard cigarette smoke.

Longitudinal assessment of myocardial edema following experimental acute myocardial infarction using a comprehensive CMR protocol

Abstract Background Preclinical and clinical data following acute myocardial infarction (MI) and reperfusion have shown a bimodal pattern of edematous myocardium at risk (MaR) on cardiovascular magnetic resonance (CMR) imaging during the first week [1,2]. In contrary, there have also been data demonstrating that MaR is stable during the first week in patients using contrast-enhanced steady-state free precession (CE-SSFP) imaging [3]. Purpose To use a comprehensive CMR protocol to assess the dynamics of edematous MaR during the first week following acute experimental MI. Methods Acute myocardial ischemia was induced in seven pigs by endovascular balloon occlusion in the left anterior descending artery with reperfusion after 40 minutes. CMR was performed at baseline, at 120 minutes, 24 hours and seven days post-reperfusion on a 1.5T scanner. The CMR protocol comprised of a prototype T2-SSFP sequence where two experiments with 16 echo times (T2 mapping16) and with 10 echo times (T2 mapping10) [1] were performed. After contrast administration, a short-axis CE-SSFP stack and late gadolinium enhancement (LGE) images were acquired. T2-maps were acquired in a mid-apical ventricular short-axis slice corresponding to the same anatomical level at all time points. All image analysis was performed using designated software. Severity of MaR was measured by placing a region of interest in the ischemic area on T2 maps and extent of MaR was assessed by delineating hyperintense areas in CE-SSFP short-axis stacks. Data is presented as mean ± SD and one-way ANOVA was used followed by Tukey's multiple comparison test. Results An example of all acquired CMR sequences is shown in Figure 1, with red arrows depicting the extent of edematous MaR. Figure 2 shows the severity of MaR by T2 values from T2 mapping16 where T2 values were significantly lower at 24 hours compared to 120 minutes post-reperfusion (P&amp;lt;0.05). However, no significant difference was seen at 120 minutes or at 24 hours compared to T2 values at seven days (P=0.46 and P=0.35). No difference at baseline (47±3 ms vs 49±3 ms, P=0.10) was observed when comparing T2 mapping16 against T2 mapping10 but a significant difference between the time points 120 min (80±8 ms vs 69±7 ms, P=0.02), 24 h, (69±9 ms vs 54±4 ms, P=0.03), and seven days (76±10 ms vs 67±5 ms, P=0.04) post-reperfusion. There was no statistically significant difference between T2 values post-reperfusion using T2 mapping10 (P=ns). The extent of myocardium at risk assessed by CE-SSFP did not show a bimodal pattern of edema, but rather a significantly lower extent at seven days compared to the extent at 120 minutes and 24 hours (P&amp;lt;0.05). Conclusion The severity and extent of edematous myocardium at risk does not follow a bimodal pattern over the course of one week. However, absolute T2 values differ between T2 mapping sequences and therefore a standardization of a CMR protocol for the assessment of MaR is of importance. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): The Swedish Heart-Lung Foundation and The Medical Faculty of Lund University (ALF)

Exploring macrophage mannose receptor expression after myocardial infarction by Al[18F]F-NOTA-DCM positron emission tomography

Abstract Introduction Mannose receptor (CD206) is primarily expressed on the surface of alternatively activated macrophages that are involved in resolution of inflammation after myocardial injury [1]. The purpose of this study was to evaluate mannose receptor targeting positron emission tomography (PET) tracer Al[18F]F-NOTA-DCM consisting of dextran backbone with cysteine-mannose moieties for imaging of experimental acute myocardial infarction (MI) [2]. Methods First, ALEXA-488 fluorophore-labelled DCM was used for specificity studies using flow cytometry of M1 and M2 polarized macrophages derived from human blood monocytes. Secondly, Sprague-Dawley rats were studied on day 3 and day 7 after permanent ligation of left coronary artery or after sham-operation. [18F]FDG PET (35 MBq, 10 min static scan) was performed to visualize myocardium and on the next day, 60 min dynamic PET was performed after injection of 50 MBq of Al[18F]F-NOTA-DCM. Then, rats were euthanized for biodistribution study by gamma counting followed by digital autoradiography and histology (H&amp;E, CD206 staining) of left ventricle cryosections. In vitro Al[18F]F-NOTA-DCM blocking study was performed on left ventricle cryosection with molar excess of unlabelled DCM. Results Flow cytometry confirmed that ALEXA-488-DCM bound specifically to M2 macrophages. In rats, the infarcted area was clearly detected in vivo with Al[18F]F-NOTA-DCM PET and its SUV was significantly higher than that of remote area or myocardium of sham-operated rats both on day 3 (SUV 0.78±0.18 vs. 0.47±0.13 vs. 0.43±0.07, p&amp;lt;0.005) and day 7 post-MI (SUV 0.64±0.10 vs. 0.47±0.12 vs. 0.51±0.07, p&amp;lt;0.05). Autoradiography confirmed increased uptake in the infarcted area compared to the remote area or to the myocardium of sham-operated rats on day 3 (PSL/mm2 141.21±46.06 vs. 49.76±20.37 vs. 57.97±6.77, p&amp;lt;0.005) and day 7 (PSL/mm2 139.22±19.44 vs. 55.38±28.83 vs. 60.83±7.63, p&amp;lt;0.0001). In vitro blocking study indicated that the tracer binding in infarcted area was specific. The area-% of CD206-positive staining in the infarcted area was significantly higher on day 3 post-MI than on day 7 (p&amp;lt;0.05), and higher at both time points than in remote area or myocardium of sham-operated rats (p&amp;lt;0.0001). Area-% of CD206 staining in the MI area positively correlated with Al[18F]F-NOTA-DCM uptake and MI size (p&amp;lt;0.05 and p&amp;lt;0.01, respectively). Conclusions Al[18F]F-NOTA-DCM PET detects overexpression of mannose receptor after ischemic myocardial injury and may be a suitable biomarker for early detection of the inflammation resolution process after MI. Funding Acknowledgement Type of funding sources: Foundation. Main funding source(s): Jane and Aatos Erkko FoundationSigrid Juselius FoundationFInnish Foundation for Cardiovascular Research

ACUTE PHASE OF MYOCARDIAL INFARCTION: EFFECT OF If-CURRENT BLOCKADE ON ISOLATED RAT HEART

If-current density in cardiomyocytes changes not only with age, but also with pathophysiological hypertrophy. Thus, studies of pathological conditions in experimental animal models allow us to study If-current role in pathophysiological processes occurring in the heart after myocardial infarction (MI).&#x0D; The objective of the study is to examine the effect of If-currents blockade on the isolated heart of rats with modelled acute myocardial infarction (AMI) and sham-operated (SO) rats.&#x0D; Materials and Methods. MI was reproduced by the left coronary artery ligation. The study was conducted on a Langendorff-isolated heart (ADInstruments). During AMI, the authors studied chronotropy, inotropy and its temporal characteristics, and blood supply of the rat heart.&#x0D; Results. It was found that the initial values of contractile force and coronary flow were significantly lower in the group with an experimental AMI model. There were no differences in heart rate and temporal characteristics of contractile force. If-current blockade (ZD7288, 10-9 M, 10-5 M) reduced the contractile force and coronary flow of the isolated heart in both experimental groups, the changes were more pronounced in the SO group. If-current blockade (10-9 M) in the SO group led to tachycardia, and in the AMI group - to bradycardia. ZD7288 (10-5 M) reduced heart rate in both groups, but in the AMI group, bradycardia was more pronounced. It is possible that the obtained dynamics is associated with a change in the if-current density in the dyscrasic myocardium. Thus, it is obvious that If-currents are not only involved in the regulation of various MI heart functions, but their role changes at different stages of experimental myocardial infarction.

Abstract P1054: Oral Administration Of New Agonist Of Adenosine Receptor Reduces Inflammatory Process And Cardiac Remodeling Induced By Myocardial Infarction In Rats

Treatment of acute myocardial infarction (AMI) is based on strategies to relief pain and increase survival. Thus, this work investigates the effects of a new agonist of adenosine receptor called LASSBio-1860 in an experimental model of AMI, in order to improve cardiac function. The protocols were approved by the Ethics Committee for the Use of Animals at Federal University of Rio de Janeiro (# 103/17). The experimental AMI was induced by the ligation of the anterior descending coronary artery in male Wistar rats (180-200 g), which were randomly divided into groups treated orally with vehicle (DMSO) or 70 μmol/kg of LASSBio-1860 for 7 days. At the end of the experimental protocol, hemodynamic parameters were obtained using echocardiography and the expression of markers involved in the inflammatory pathway (TNF-alpha, p38) and cardiac remodeling (p-ERK-1/2 and t-ERK) was evaluated. AMI increased the left ventricular (LV) wall thickness from 0.11 ± 0.04 to 0.29 ± 0.02 cm (p &lt;0.05) which was reduced to 0.21 ± 0.01 cm after treatment with LASSBio-1860. The impaired ejection fraction observed after AMI (reduction from 91.5 ± 0.5 to 45.2 ± 1.3%) was partially reversed to 60.1 ± 10.3% with the treatment. Additionally, the agonist of adenosine receptor normalized the increased filling pressure of 31.3 ± 4.4 to 15.9 ± 3.9. Increased LV final systolic pressure was detected after AMI, changing from 83.8 ± 12.5 (control group) to 104.7 ± 1.1, which was recovered to 95.3 ± 21.4 mmHg with LASSBio-1860. An increase in the TNF-alpha expression as well as nuclear p38 labeling was detected in the heart from infarcted animals which was reduced after administration of LASSBio-1860. Furthermore, AMI increased the ratio of phosphorylated and total ERK-1/2 from 0.78 ± 0.01 to 0.89 ± 0.01 while treatment with LASSBio-1860 reduced to 0.79 ± 0.01 (p &lt; 0.05). Similarly, p38 increased from 0.72 ± 0.11 to 1.58 ± 0.36 induced by AMI but was reduced to 1.17 ± 0.43 by LASSBio-1860. An increase in collagen deposition from 3.6 ± 0.9 to 31.5 ± 4.29 was observed in hearts from infarcted animals, which was reduced to 26.8 ± 1.6 with treatment. Also, AMI promoted an increase in p38 nuclear labeling from 9.9 ± 3.9 to 40.8 ± 3.3 which was decreased to 29.9 ± 1.7 in treated animals. Similar increase and recovery was detected with iNOS because AMI caused an increase from 9.0 ± 4.1 to 25.3 ± 3.9 and improvement to 14.2 ± 0.6. In conclusion, the reduction of the inflammatory response may be related to the activation of adenosine receptors by LASSBio-1860, which leads to an improvement in AMI-induced cardiac remodeling and dysfunction.

Abstract P2043: Interleukin-1 Blockade Restores Exercise Capacity After Non-reperfused Acute Myocardial Infarction In The Mouse.

Background: Acute myocardial infarction (AMI) is associated with an intense inflammatory response promoting progression to heart failure (HF), characterized by dyspnea, fatigue, exercise intolerance. Interleukin-1 (IL-1) is the prototypical inflammatory cytokine increased in AMI. IL-1 injections reduce exercise capacity in healthy mice. Whether IL-1 reduces exercise capacity after AMI is unknown. Hypothesis: IL-1 blockade preserves exercise capacity in mice with experimental AMI. Methods: Ten-week-old male CD1 mice (N=45) were trained to run on a treadmill. Baseline exercise capacity was assessed. Based on the distance run, the mice were divided into tertiles. Mice in the middle tertile underwent surgical ligation of the coronary artery. Ten mice survived and were randomly assigned to treatment with daily intraperitoneal injections with anakinra, a recombinant human IL-1 receptor antagonist (10 mg/kg, 0.2 ml, N=4), or 0.9% NaCl vehicle (N=6). We measured exercise capacity at 1, 2, and 4 weeks. Data were analyzed using T-test for unpaired groups and are presented as mean and standard error of mean. Results: Baseline exercise capacity was 217±16 and 230±16 m in the anakinra and vehicle groups, respectively. Exercise capacity was significantly reduced 1 week after surgery in both groups (-57±9% vs -60±7%, P=0.80; P&lt;0.01 vs respective baseline). By week 4, however, anakinra treatment significantly improved exercise capacity compared to the vehicle (+42±4% vs +8±7%, P&lt;0.001) (Figure). Conclusion: Non-reperfused AMI leads to a severe reduction in exercise capacity that is reversed by IL-1 blockade. These data support IL-1 as a therapeutic target for preventing HF after AMI.

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

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

Secretome of Stressed Peripheral Blood Mononuclear Cells Alters Transcriptome Signature in Heart, Liver, and Spleen after an Experimental Acute Myocardial Infarction: An In Silico Analysis.

Simple SummaryAcute myocardial infarction is characterized by impaired coronary blood flow, which leads to cardiac ischemia and, ultimately, compromised heart function. Damage and cellular responses are not limited to the non-perfused area, but rather affect the entire heart, as well as distal organs, such as the liver and spleen. We found that the therapeutic secretome of stressed white blood cells improved short-term and long-term cardiac performance in a porcine infarction model. In order to unravel the molecular events governing secretome-mediated tissue regeneration, we performed transcriptional analyses of the non-perfused, transition, and perfused heart, as well as the liver and spleen 24 h after myocardial infarction. We observed a highly tissue-specific effect of the secretome and, except for the transition zone, a uniform downregulation of pro-inflammatory factors and pathways. Simultaneously, the secretome strongly promoted the expression of genes that are essential for heart function in the non-perfused area. In the liver and spleen, different metabolic processes were induced. Together, our data suggest several plausible mechanisms by which the secretome improves heart function after cardiac ischemia. Deepening our understanding of the molecular processes identified here might uncover further pharmacologic strategies aiming at delimiting adverse cardiac remodeling and sequelae after myocardial infarction.Acute myocardial infarction (AMI) is a result of cardiac non-perfusion and leads to cardiomyocyte necrosis, inflammation, and compromised cardiac performance. Here, we showed that the secretome of γ-irradiated peripheral blood mononuclear cells (PBMCsec) improved heart function in a porcine AMI model and displayed beneficial long- and short-term effects. As an AMI is known to strongly affect gene regulation of the ischemia non-affected heart muscle and distal organs, we employed a transcriptomics approach to further study the immediate molecular events orchestrated using the PBMCsec in myocardium, liver, and spleen 24 h post ischemia. In the infarcted area, the PBMCsec mainly induced genes that were essential for cardiomyocyte function and simultaneously downregulated pro-inflammatory genes. Interestingly, genes associated with pro-inflammatory processes were activated in the transition zone, while being downregulated in the remote zone. In the liver, we observed a pronounced inhibition of immune responses using the PBMCsec, while genes involved in urea and tricarboxylic cycles were induced. The spleen displayed elevated lipid metabolism and reduced immunological processes. Together, our study suggested several types of pharmacodynamics by which the PBMCsec conferred immediate cardioprotection. Furthermore, our data supported the assumption that an AMI significantly affects distal organs, suggesting that a holistic treatment of an AMI, as achieved by PBMCsec, might be highly beneficial.

The assessment of lactate in experimental acute myocardial infarction

The assessment of lactate in experimental acute myocardial infarction

Intrapericardial Delivery of APA-Microcapsules as Promising Stem Cell Therapy Carriers in an Experimental Acute Myocardial Infarction Model

The administration of cardiosphere-derived cells (CDCs) after acute myocardial infarction (AMI) is very promising. CDC encapsulation in alginate-poly-l-lysine-alginate (APA) could increase cell survival and adherence. The intrapericardial (IP) approach potentially achieves high concentrations of the therapeutic agent in the infarcted area. We aimed to evaluate IP therapy using a saline vehicle as a control (CON), a dose of 30 × 106 CDCs (CDCs) or APA microcapsules containing 30 × 106 CDCs (APA-CDCs) at 72 h in a porcine AMI model. Magnetic resonance imaging (MRI) was used to determine the left ventricular ejection fraction (LVEF), infarct size (IS), and indexed end diastolic and systolic volumes (EDVi; ESVi) pre- and 10 weeks post-injection. Programmed electrical stimulation (PES) was performed to test arrhythmia inducibility before euthanasia. Histopathological analysis was carried out afterwards. The IP infusion was successful in all animals. At 10 weeks, MRI revealed significantly higher LVEF in the APA-CDC group compared with CON. No significant differences were observed among groups in IS, EDVi, ESVi, PES and histopathological analyses. In conclusion, the IP injection of CDCs (microencapsulated or not) was feasible and safe 72 h post-AMI in the porcine model. Moreover, CDCs APA encapsulation could have a beneficial effect on cardiac function, reflected by a higher LVEF at 10 weeks.

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

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

Studying the Innate Immune Response to Myocardial Infarction in a Highly Efficient Experimental Animal Model

Abstract The reduction in mortality following acute myocardial infarction (AMI) is an important achievement of modern medicine. Despite this progress, AMI remains the most common cause of heart failure (HF) and HF-related morbidity and mortality. The involvement of the innate immune response in different stages after AMI has at tracted important attention in recent years. With the increasing range of potential therapeutic compounds and delivery vectors, the need of highly efficient experimental AMI models is increasing, to support further advancement in this field. Here, we present a high-throughput model for the assessment of the innate immune response to AMI. The model is based on permanent surgical ligation of the left descending coronary artery (LAD) in mice, followed by complex flow-cytometry and histological analyses of immune cellular populations in blood and myocardium. We are presenting time-dependent qualitative and quantitative analysis results, demonstrating intense accumulation of Ly6Ghi neutrophils and Ly6Chi monocytes in the infarcted myocardium on days 1 and 3 post-AMI, followed by successive accumulation of reparatory Ly6CloMerTKhi macrophages, neovascularization and fibrosis development by day 7.

Interleukin-1α Is a Central Regulator of Leukocyte-Endothelial Adhesion in Myocardial Infarction and in Chronic Kidney Disease.

Cardiovascular diseases and chronic kidney disease (CKD) are highly prevalent, aggravate each other, and account for substantial mortality. Both conditions are characterized by activation of the innate immune system. The alarmin interleukin-1α (IL-1α) is expressed in a variety of cell types promoting (sterile) systemic inflammation. The aim of the present study was to examine the role of IL-1α in mediating inflammation in the setting of acute myocardial infarction (AMI) and CKD. We assessed the expression of IL-1α on the surface of monocytes from patients with AMI and patients with CKD and determined its association with atherosclerotic cardiovascular disease events during follow-up in an explorative clinical study. Furthermore, we assessed the inflammatory effects of IL-1α in several organ injury models in Il1a-/- and Il1b-/- mice and investigated the underlying mechanisms in vitro in monocytes and endothelial cells. IL-1α is strongly expressed on the surface of monocytes from patients with AMI and CKD compared with healthy controls. Higher IL-1α surface expression on monocytes from patients with AMI and CKD was associated with a higher risk for atherosclerotic cardiovascular disease events, which underlines the clinical relevance of IL-1α. In mice, IL-1α, but not IL-1β, mediates leukocyte-endothelial adhesion as determined by intravital microscopy. IL-1α promotes accumulation of macrophages and neutrophils in inflamed tissue in vivo. Furthermore, IL-1α on monocytes stimulates their homing at sites of vascular injury. A variety of stimuli such as free fatty acids or oxalate crystals induce IL-1α surface expression and release by monocytes, which then mediates their adhesion to the endothelium via IL-1 receptor-1. IL-1α also promotes expression of the VCAM-1 (vascular cell adhesion molecule-1) on endothelial cells, thereby fostering the adhesion of circulating leukocytes. IL-1α induces inflammatory injury after experimental AMI, and abrogation of IL-1α prevents the development of CKD in oxalate or adenine-fed mice. IL-1α represents a key mediator of leukocyte-endothelial adhesion and inflammation in AMI and CKD. Inhibition of IL-1α may serve as a novel anti-inflammatory treatment strategy.

MO592INTERLEUKIN-1A (IL-1A) IS A CENTRAL REGULATOR OF INFLAMMATION IN CARDIOVASCULAR AND KIDNEY DISEASES

Abstract Background and Aims Cardiovascular diseases (CVD) and chronic kidney disease (CKD) are highly prevalent, aggravate each other, and account for substantial mortality. Both conditions are characterized by activation of the innate immune system. The alarmin IL-1α is expressed in a variety of cell types promoting (sterile) systemic inflammation. The aim of the present study is to examine the role of IL-1α in mediating inflammation in the setting of cardiorenal diseases. Method We assessed the expression of IL-1α on the surface of monocytes from patients with acute myocardial infarction (AMI) and patients with CKD and determined its association with atherosclerotic CVD events during follow-up in an explorative clinical study. Furthermore, we assessed the inflammatory effects of IL-1α in several organ injury models in Il1a -/- and Il1b -/- mice and investigated the underlying mechanisms in vitro in monocytes and endothelial cells. Results IL-1α is strongly expressed on the surface of monocytes from patients with AMI and CKD compared to healthy controls. Higher IL-1α surface expression on monocytes from patients with AMI was associated with a higher risk for atherosclerotic CVD events, which underlines the clinical relevance of IL-1α. In mice, IL-1α, but not IL-1β, mediates leukocyte-endothelial adhesion as determined by intravital microscopy. IL-1α promotes accumulation of macrophages and neutrophils in inflamed tissue in-vivo . Furthermore, IL-1α on monocytes stimulates their homing at sites of vascular injury. A variety of stimuli such as free fatty acids or oxalate crystals induce IL-1α surface expression and release by monocytes, which then mediates their adhesion to the endothelium via IL-1 receptor-1. Besides, IL-1α promotes expression of the vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells thereby fostering the adhesion of circulating leukocytes. IL-1α induces inflammatory injury after experimental AMI and abrogation of IL-1α prevents the development of CKD in oxalate or adenine-fed mice. Conclusion IL-1α represents a key mediator of leukocyte-endothelial adhesion and inflammation in cardiorenal diseases. Inhibition of IL-1α may serve as a novel anti-inflammatory treatment strategy.

Left Ventricular Assist Devices for Acute Myocardial Infarct Size Reduction: Meta-analysis.

We conducted a meta-analysis of preclinical studies that tested left ventricular assist device (LVAD) therapy for reducing myocardial infarct size in experimental acute myocardial infarction (AMI). Twenty-six articles were included with a total of 488 experimental animal subjects. The meta-analysis showed that infarct size was significantly decreased by LVAD support compared to control animals (SDM, - 2.19; 95% CI, - 2.70 to - 1.69; P < 0.001). The meta-regression analysis demonstrated a high degree of heterogeneity associated with time from coronary artery occlusion to LVAD support, which correlated positively with infarct size. Subgroup analysis suggested smaller infarct size in LVAD therapies that withdrew blood from left heart than those from right heart. The proportion of left ventricular support relative to total cardiac output was positively correlated with infarct size reduction in Impella studies. Thus, early initiation of LVAD after ischemia and effective left ventricular venting may be important factors to reduce infarct size in AMI.

The condition of neuro-endocrine systems in acute experimental myocardial infarction against the background of various reactivity of the organism

The adequacy of recovery processes in myocardial infarction (MI) significantly depends on the state of reactivity of the organism, which, in turn, is determined by the adequacy of neuro-endocrine regulation, in particular, hypothalamic-pituitary-adrenocortical (HPA) and hypothalamic-pituitary-thyroid (HPT) system system.Purpose of the study. To investigate the condition of HPA and HPT in acute experimental MI against the background of different reactivity of the organism.Material and methods. The study was performed on 20 outbred adult dogs weighing 8-12 kg, in which MI was simulated by ligation of the anterior interventricular artery. Animals were divided into three groups (n =5 in each group). The condition of hyperreactivity was caused by the introduction of pyrogenal (group 2), the state of hyporeactivity - the introduction of azothioprine (group 3), in group 1 drugs were not used (state of normoreactivity). In the control group used 5 falsely operated dogs with thoracopericardiotomy. In animals before surgery, on 1, 4, 7, 11 and 15 days in the blood was determined by the content of adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH) , cortisol (Cr), aldosterone (Ald), thyroxine and triiodothyronine. Statistical processing was performed using license packages Statistica 5.5 (Stat Soft Rus), Statistica Neural Networks (Statsoft Inc.).Results. Normoreactive course of myocardial infarction was characterized by primary activation of HPA, which was most pronounced for Cortisol, followed by restoration of ACTH and Aldosterone levels and duration of activation of the central link up to 4 days, peripheral - up to 7-11 days; reciprocal in relation to HPA inhibition of the functional activity of the HPT, most pronounced on the 4th day and lasting up to 15 days. Such changes caused the healing of myocardial infarction through the formation of a full-fledged post-infarction scar. The hyperreactive course of myocardial infarction was characterized by hypersecretion of ACTH with hypercorticism and hyperaldosteronism and less pronounced suppression of HPT with the restoration of its functional activity on the 7th day. The hyporeactive course of myocardial infarction was characterized by a minimally pronounced and delayed up to 4 days activation of HPA with Aldosterone hyposecretion on the 15th day; deep hypothyroidism of both central and peripheral genesis. Impaired reactivity was accompanied by an increase in the area of necrosis and a decrease in the thickness of the heart wall with the formation of postinfarction aneurysm.Conclusions. Desynchronization of necrotic and reparative processes with a change in reactivity leads to a disruption in the relationship between necrosis and repair with the formation of postinfarction aneurysm, which is accompanied by different activities of the HPA and HPT.