Experimental Myocardial Infarction Research Articles

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.

Spatio-temporal regulation of calpain activity after experimental myocardial infarction in vivo

BackgroundCalpains are calcium activated cysteine proteases that play a pivotal role in the pathophysiology of cardiac remodeling. MethodsHere, we performed left anterior descending coronary artery ligation in rats as a model for ischemic systolic heart failure and examined the time- and region-specific regulation of calpain-1 and calpain-2 in the left ventricular myocardium. ResultsFollowing anterior wall myocardial infarction, calpain activity was significantly increased restricted to the ischemic anterior area at days 1, 5 and 14. No changes in calpain activity at neither time point were detected in the borderzone and remote posterior area of the left ventricle. Of note, calpain activity in the infarcted anterior myocardium was regulated differentially in the acute vs. subacute and chronic phase. In the acute phase, calpain translocation to the plasma membrane and attenuation of the expression of its endogenous inhibitor, calpastatin, were identified as the driving forces. In the subacute and chronic phase, calpain activity was regulated at the level of protein expression that was shown to be essentially independent of transcriptional activity. ConclusionsWe conclude that myocardial infarction leads to a distinct calpain regulation pattern in the left ventricular myocardium that is region specific and time dependent. Considering the results from our previous studies, a spatio-temporal interaction between calpains and calcium dependent natriuretic peptide production in the infarcted myocardium is possible. General significanceOur results shed more light in the differential regulation of calpain activity in the myocardium and might aid in the development of targeted post-infarct and/or heart failure therapeutics.

Therapeutic activity of sarpogrelate and dopamine D2 receptor agonists on cardiovascular and renal systems in rats with alloxan-induced diabetes

BackgroundDopamine D2 receptor agonists, bromocriptine and cabergoline, are notable medications in the treatment of Parkinsonism, hyperprolactinemia, and hyperglycemia. An affiliation was found between the initiation of myocardial injury ailment and long term treatment with dopamine D2 agonist drugs identified with the partial activation of 5-hydroxytryptamine receptor 2 A (5-HT2A). The investigation aimed to examine the activity of sarpogrelate (a 5-HT2A receptor blocker) in reducing myocardial injury prompted by extended haul utilisation of D2 receptor agonists in rats with alloxan-induced diabetes.MethodsBoth bromocriptine and cabergoline were managed independently and combined with sarpogrelate for about a month in diabetic nephropathy rats. Both tail-cuff blood pressure and the BGL were recorded weekly. For all animals, the kidney hypertrophy index, serum creatinine, blood urea nitrogen, alanine transaminase, and aspartate transaminase levels were measured after one month of treatment. The severity of the cardiac injury was assessed by the estimation of lactate dehydrogenase-1 (LDH-1), cardiac troponin I, and tumor necrosis factor alpha 1 (TNF1). The triphenyltetrazolium chloride (TTC) staining method was used to determine the experimental myocardial infarction (MI) size.ResultsBromocriptine and cabergoline created a significant reduction in BGL, BP, and kidney hypertrophy index in diabetic nephropathy rats. Administration of bromocriptine and cabergoline, alone, or in combination with sarpogrelate fundamentally diminished the blood concentrations of alkaline phosphatase (ALP), Aspartate aminotransferase (AST), urea, and creatinine. Bromocriptine and cabergoline alone showed a noteworthy increase in the LDH-1, Troponin I, and TNF1 levels in the serum (p < 0.05). Paradoxically, utilising bromocriptine or cabergoline with sarpogrelate treatment altogether decreased the levels of the myocardial biomarkers in the serum. A mix of bromocriptine or cabergoline with sarpogrelate diminished the level of the myocardial infarct size in the heart assessed through the TTC staining method.ConclusionsThe examination demonstrated that the combined use of sarpogrelate with bromocriptine or cabergoline decreased the potential adverse effects of these two drugs on the myocardial tissues.

The Effect of Endurance Training on Plasma Levels of ICAM, VCAM, and OPG in Rats with Experimental Myocardial Infarction: A Gender-Based Study

Background: The purpose of this study was to investigate the effect of four weeks of endurance training (EXE) on inflammatory markers predicting atherosclerosis by gender. Materials and Methods: Forty male and female Wistar rats were divided into 4 groups including male myocardial infarction (MI), male MI + EXE, female MI, and female MI+EXE. After the induction of MI with two intraperitoneal injections of isoproterenol (150 mg/kg), the training groups performed an (EXE) program for 4 weeks on a treadmill (speed 18 m/min, 30 minutes, 5 sessions per week). The animals were sacrificed 24 hours after the last training session. Finally, data were analyzed using a two-way analysis of variance and Fishers’ least significant difference post hoc test. Results: Despite the clinical difference in the training groups, the intercellular adhesion molecule (ICAM, 3.74±0.61 ng/mL) was more significant in the female MI + EXE group (P=0.009). Conclusion: In general, despite observing clinical changes, there were no significant vascular cell adhesion molecules and osteoprotegerin (OPG) after EXE in cardiovascular inflammatory factors in male and female rats following MI. Nevertheless, gender had a significant independent effect on the ICAM index. The results showed that ICAM values were higher in female rats in comparison with male rats.

Effect of neuregulin-1 on cardiac glucose metabolism in rats with experimental myocardial infarction

Objective: To investigate the effect of neuregulin-1(NRG-1) on cardiac glucose metabolism in Sprague Dawley (SD) rats with experimental myocardial infarction (MI). Methods: Adult male SD rats were randomly divided into three groups: the sham-operated group, MI group, and MI+NRG1 group. The rat MI model was established via ligation of the left anterior descending coronary artery. Two weeks after operation, echocardiography was performed, MI rats with left ventricular ejection fraction (LVEF) between 0.3-0.5 were selected and randomly assigned to MI group and MI+NRG-1 group. Rats in MI+NRG-1 group were treated with recombinant human NRG-1β (100 μg/kg) via tail vein at 2 weeks after operation (twice per week for 6 weeks); while rats in sham-operated group and MI group received equal volume of physiological saline. By the end of administration, echocardiography and small animal positron emission tomography (PET) were performed to detect cardiac function and myocardial glucose uptake. Myocardial morphology and collagen volume fraction, cardiomyocyte apoptosis and reactive oxygen species (ROS) production were evaluated by histopathologic analysis. Myocardial pyruvate dehydrogenase (PDH) and citrate synthase (CS) activity, as well as ATP production were detected by commercial kits. The mRNA and protein expression levels of NRG-1, p-ErbB4, and key factors involved in glucose metabolism (including Glut-4, HK2, PDK4, PDH, CS) were detected by quantitative real-time PCR (qRT-PCR) and Western blot assay, respectively. Results: With the MI model successfully established, the left ventricular ejection fraction(LVEF) and left ventricular shortening fraction(LVFS) were significantly lower in MI group and MI+NRG-1 group than that in sham group (both P<0.01), while there was no significant difference between MI group and MI+NRG-1 group(all P>0.05). After 6 weeks of NRG-1β intervention, the LVEF and LVFS were significantly higher in MI+NRG-1 group than in MI group (both P<0.01). By the end of experiment, PET imaging showed that the mean standardized uptake value (SUVmean) were lower in MI+NRG-1 group than in the sham group (4.06±0.28 vs. 5.18±0.37, P<0.01), while significantly higher than that in MI group (4.06±0.28 vs.2.86±0.49, P<0.01). Histopathological analysis showed that compared with MI group, rats in MI+NRG-1 group exhibited significantly decreased left ventricle collagen volume fraction ((7.83±1.24) % vs. (18.31±3.58) %, P<0.01), cardiomyocyte apoptosis((37.98±4.26)% vs. (67.04±5.38)%, P<0.01), and DHE fluorescence intensity(0.057 28±0.007 06 vs. 0.076 94±0.008 46, P<0.01), indicating that NRG-1β could reduce ROS production. PDH activity, CS activity, and ATP production were significantly higher in MI+NRG-1 group than in MI group (all P<0.05). qRT-PCR demonstrated an upregulated Glut-4, HK2 and CS, but downregulated PDK4 mRNA expression in MI+NRG-1 group compared with MI group (all P<0.01). Western blot assay showed significantly higher protein expression of NRG-1, p-ErbB4, Glut-4, HK2, PDH, CS in MI+NRG-1 group than in MI group (all P<0.01). Conclusion: NRG-1 could improve glucose uptake and utilization in myocardium by activating phosphorylation of myocardial ErbB4 receptor in MI rats, thus providing a therapeutic option for improving energy metabolism after MI.

Innate Lymphoid Cells Promote Recovery of Ventricular Function After Myocardial Infarction

BackgroundInnate lymphoid cells type 2 (ILC2s) play critical homeostatic functions in peripheral tissues. ILC2s reside in perivascular niches and limit atherosclerosis development. ObjectivesILC2s also reside in the pericardium but their role in postischemic injury is unknown. MethodsWe examined the role of ILC2 in a mouse model of myocardial infarction (MI), and compared mice with or without genetic deletion of ILC2. We determined infarct size using histology and heart function using echocardiography. We assessed cardiac ILC2 using flow cytometry and RNA sequencing. Based on these data, we devised a therapeutic strategy to activate ILC2 in mice with acute MI, using exogenous interleukin (IL)-2. We also assessed the ability of low-dose IL-2 to activate ILC2 in a double-blind randomized clinical trial of patients with acute coronary syndromes (ACS). ResultsWe found that ILC2 levels were increased in pericardial adipose tissue after experimental MI, and genetic ablation of ILC2 impeded the recovery of heart function. RNA sequencing revealed distinct transcript signatures in ILC2, and pointed to IL-2 axis as a major upstream regulator. Treatment of T-cell–deficient mice with IL-2 (to activate ILC2) significantly improved the recovery of heart function post-MI. Administration of low-dose IL-2 to patients with ACS led to activation of circulating ILC2, with significant increase in circulating IL-5, a prototypic ILC2-derived cytokine. ConclusionsILC2s promote cardiac healing and improve the recovery of heart function after MI in mice. Activation of ILC2 using low-dose IL-2 could be a novel therapeutic strategy to promote a reparative response after MI.

Assessment of myocardial viability with [15O]water PET: A validation study in experimental myocardial infarction

BackgroundAssessment of myocardial viability is often needed in patients with chest pain and reduced ejection fraction. We evaluated the performance of reduced resting MBF, perfusable tissue fraction (PTF), and perfusable tissue index (PTI) in the assessment of myocardial viability in a pig model of myocardial infarction (MI). Methods and resultsPigs underwent resting [15O]water PET perfusion study 12 weeks after surgical (n = 16) or 2 weeks after catheter-based (n = 4) occlusion of the proximal left anterior descending coronary artery. MBF, PTF, and PTI were compared with volume fraction of MI in matched segments as assessed by triphenyl tetrazolium chloride staining of LV slices. MBF and PTF were lower in infarcted than non-infarcted segments. Segmental analysis of MBF showed similar area under the curve (AUC) of 0.85, 0.86, and 0.90 with relative MBF, PTF, and PTI for the detection of viable myocardium defined as infarct volume fraction of < 75%. Cut-off values of relative MBF of ≥ 67% and PTF of ≥ 66% resulted in accuracies of 90% and 81%, respectively. ConclusionsOur results indicate that resting MBF, PTF, and PTI based on [15O]water PET perfusion imaging are useful for the assessment of myocardial viability.

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.

Comparative evaluation of empagliflozin, canagliflozin and sitagliptin cardioprotective properties in rats with experimental type 2 diabetes mellitus

Background: Myocardial infarction (MI) is one of the leading causes of mortality in patients with type 2 diabetes mellitus (DM), therefore it is essential to give preference to a glucose-lowering drug having optimal cardioprotective properties. A comparative study of the various sodium-glucose co-transporter inhibitors representatives’ protective effects in experimental MI was not carried out within the framework of one study.Aim: To evaluate the influence of empagliflozin (EMPA) and canagliflozin (CANA), in comparison with sitagliptin (SITA), on hemodynamic parameters and myocardial damage area in rats with diabetes type 2 model in experimental MI.Materials and methods: Type 2 DM was modelled in Wistar rats by means of 4-week high-fat diet followed by nicotinamide 230 mg/kg and streptozotocin 60 mg/kg administration. 4 weeks after DM induction the following groups were made: «DM+SITA» — treatment with SITA 50 mg/kg, «DM+EMPA» — treatment with EMPA 2 mg/kg, «DM+CANA» — treatment with CANA 25 mg/kg per os once daily for 8 weeks. Animals in «DM» group remained untreated for the following 8 weeks. Rats in control group were fed with standard chow. 16 weeks after the experiment beginning transient global myocardial ischemia was modelled in all rats. Hemodynamic parameters and myocardium necrosis area were evaluated.Results: The necrosis area was larger in «DM» group, than in control one (p=0.018). Infarction size in «DM+SITA» did not differ from that in «DM» group (62.92(41.29;75.84) and 57.26(45.51;70.08)%, р=0.554). Necrosis area in «DM+EMPA» and «DM+CANA» groups was smaller than in «DM» group (37.90(20.76;54.66)%, 46.15(29.77;50.55) vs 57.26(45.51;70.08)%, р=0.008 and р=0.009, respectively). Necrosis size did not differ between «DM+EMPA» and «DM+CANA» groups (p=0.630). Ischemic contracture in «DM+CANA» group was less prominent than under the use of all other glucose-lowering drugs. We observed increase of coronary blood flow in «DM+EMPA» group, in comparison with «DM», «DM+CANA» and «DM+SITA» groups.Conclusions: SITA does not have cardioprotective effect in ischemia-reperfusion injury in diabetic rats. EMPA and CANA have similarly prominent infarct-limiting properties. EMPA is able to increase coronary blood flow, whereas cardioprotective action of CANA is associated with ischemic contracture diminishing.

Interleukin-5-induced eosinophil population improves cardiac function after myocardial infarction.

Interleukin (IL)-5 mediates the development of eosinophils (EOS) that are essential for tissue post-injury repair. It remains unknown whether IL-5 plays a role in heart repair after myocardial infarction (MI). This study aims to test whether IL-5-induced EOS population promotes the healing and repair process post-MI and to reveal the underlying mechanisms. MI was induced by permanent ligation of the left anterior descending coronary artery in wild-type C57BL/6 mice. Western blot and real-time polymerase chain reaction revealed elevated expression of IL-5 in the heart at 5 days post-MI. Immunohistostaining indicated that IL-5 was secreted mainly from macrophages and CD127+ cells in the setting of experimental MI. External supply of recombinant mouse IL-5 (20 min, 1 day, and 2 days after MI surgery) reduced the infarct size and increased ejection fraction and angiogenesis in the border zone. A significant expansion of EOS was detected in both the peripheral blood and infarcted myocardium after IL-5 administration. Pharmacological depletion of EOS by TRFK5 pretreatment muted the beneficial effects of IL-5 in MI mice. Mechanistic studies demonstrated that IL-5 increased the accumulation of CD206+ macrophages in infarcted myocardium at 7 days post-MI. In vitro co-culture experiments showed that EOS shifted bone marrow-derived macrophage polarization towards the CD206+ phenotypes. This activity of EOS was abolished by IL-4 neutralizing antibody, but not IL-10 or IL-13 neutralization. Western blot analyses demonstrated that EOS promoted the macrophage downstream signal transducer and activator of transcription 6 (STAT6) phosphorylation. IL-5 facilitates the recovery of cardiac dysfunction post-MI by promoting EOS accumulation and subsequent CD206+ macrophage polarization via the IL-4/STAT6 axis.

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.

Interventricular Differences of Signaling Pathways-Mediated Regulation of Cardiomyocyte Function in Response to High Oxidative Stress in the Post-Ischemic Failing Rat Heart.

Standard heart failure (HF) therapies have failed to improve cardiac function or survival in HF patients with right ventricular (RV) dysfunction suggesting a divergence in the molecular mechanisms of RV vs. left ventricular (LV) failure. Here we aimed to investigate interventricular differences in sarcomeric regulation and function in experimental myocardial infarction (MI)-induced HF with reduced LV ejection fraction (HFrEF). MI was induced by LAD ligation in Sprague–Dawley male rats. Sham-operated animals served as controls. Eight weeks after intervention, post-ischemic HFrEF and Sham animals were euthanized. Heart tissue samples were deep-frozen stored (n = 3–5 heart/group) for ELISA, kinase activity assays, passive stiffness and Ca2+-sensitivity measurements on isolated cardiomyocytes, phospho-specific Western blot, and PAGE of contractile proteins, as well as for collagen gene expressions. Markers of oxidative stress and inflammation showed interventricular differences in post-ischemic rats: TGF-β1, lipid peroxidation, and 3-nitrotyrosine levels were higher in the LV than RV, while hydrogen peroxide, VCAM-1, TNFα, and TGF-β1 were increased in both ventricles. In addition, nitric oxide (NO) level was significantly decreased, while FN-1 level was significantly increased only in the LV, but both were unchanged in RV. CaMKII activity showed an 81.6% increase in the LV, in contrast to a 38.6% decrease in the RV of HFrEF rats. Cardiomyocyte passive stiffness was higher in the HFrEF compared to the Sham group as evident from significantly steeper Fpassive vs. sarcomere length relationships. In vitro treatment with CaMKIIδ, however, restored cardiomyocyte passive stiffness only in the HFrEF RV, but had no effect in the HFrEF LV. PKG activity was lower in both ventricles in the HFrEF compared to the Sham group. In vitro PKG administration decreased HFrEF cardiomyocyte passive stiffness; however, the effect was more pronounced in the HFrEF LV than HFrEF RV. In line with this, we observed distinct changes of titin site-specific phosphorylation in the RV vs. LV of post-ischemic rats, which may explain divergent cardiomyocyte stiffness modulation observed. Finally, Ca2+-sensitivity of RV cardiomyocytes was unchanged, while LV cardiomyocytes showed increased Ca2+-sensitivity in the HFrEF group. This could be explained by decreased Ser-282 phosphorylation of cMyBP-C by 44.5% in the RV, but without any alteration in the LV, while Ser-23/24 phosphorylation of cTnI was decreased in both ventricles in the HFrEF vs. the Sham group. Our data pointed to distinct signaling pathways-mediated phosphorylations of sarcomeric proteins for the RV and LV of the post-ischemic failing rat heart. These results implicate divergent responses for oxidative stress and open a new avenue in targeting the RV independently of the LV.

Protective Effects of Sacubitril/Valsartan on Cardiac Fibrosis and Function in Rats With Experimental Myocardial Infarction Involves Inhibition of Collagen Synthesis by Myocardial Fibroblasts Through Downregulating TGF-β1/Smads Pathway.

Objectives: To investigate the effect and mechanism of sacubitril/valsartan on myocardial fibrosis in rats following experimental myocardial infarction and in TGF-β1-treated myocardial fibroblasts. Methods: Male Sprague-Dawley (SD) rats were subjected to coronary artery ligation to establish myocardial infarction and intragastrically fed vehicle, valsartan (Val, 32 mg/kg, once-daily) or sacubitril/valsartan (Sac/Val, 68 mg/kg, once-daily) for 4 weeks. In parallel, myocardial fibroblasts (MFs) isolated from neonatal SD rats were exposed to hypoxia and treated with TGF-β1 (5 ng/ml) plus vehicle, Val (107–10–5 M) or Sac/Val (107–105 M). Rat cardiac function and fibrosis were measured by echocardiography and histological method, respectively. MFs viability and collagen synthesis were determined by cell counting kit-8 and enzyme-linked immunosorbent assay, respectively. Protein expressions of TGF-β1, Smad3, phosphorylated Smad3 (p-Smad3), and p-Smad3 subcellular localization were detected by immunoblotting and immunocytochemistry. Results: Sac/Val significantly improved cardiac structure and function in rats after myocardial infarction, including decreased left ventricular end-diastolic diameter and interventricular septal thickness, increased ejection fraction, and reduced myocardial collagen volume fraction and type Ⅰ and type Ⅲ collagen levels, and this effect was superior to that of Val. Besides, Sac/Val inhibited myocardial TGF-β1 and p-Smad3 protein expression better than Val. Mechanically, Sac/Val significantly attenuated TGF-β1-induced proliferation and collagen synthesis of MFs, and inhibit Smad3 phosphorylation and nucleus translocation, and this effect outperformed Val. Overexpression and silencing of Smad3 enhanced and reversed the inhibitory effects of Sac/Val on TGF-β1-induced collagen synthesis by MFs, respectively. Conclusions: Sacubitril/valsartan improves cardiac function and fibrosis in rats after experimental myocardial infarction, and this effect is related to the inhibition of collagen synthesis in myocardial fibroblasts by inhibiting the TGF/Smads signaling pathway.

A Novel Circulating MicroRNA for the Detection of Acute Myocarditis

BackgroundThe diagnosis of acute myocarditis typically requires either endomyocardial biopsy (which is invasive) or cardiovascular magnetic resonance imaging (which is not universally available). Additional approaches to diagnosis are desirable. We sought to identify a novel microRNA for the diagnosis of acute myocarditis.MethodsTo identify a microRNA specific for myocarditis, we performed microRNA microarray analyses and quantitative polymerase-chain-reaction (qPCR) assays in sorted CD4+ T cells and type 17 helper T (Th17) cells after inducing experimental autoimmune myocarditis or myocardial infarction in mice. We also performed qPCR in samples from coxsackievirus-induced myocarditis in mice. We then identified the human homologue for this microRNA and compared its expression in plasma obtained from patients with acute myocarditis with the expression in various controls.ResultsWe confirmed that Th17 cells, which are characterized by the production of interleukin-17, are a characteristic feature of myocardial injury in the acute phase of myocarditis. The microRNA mmu-miR-721 was synthesized by Th17 cells and was present in the plasma of mice with acute autoimmune or viral myocarditis but not in those with acute myocardial infarction. The human homologue, designated hsa-miR-Chr8:96, was identified in four independent cohorts of patients with myocarditis. The area under the receiver-operating-characteristic curve for this novel microRNA for distinguishing patients with acute myocarditis from those with myocardial infarction was 0.927 (95% confidence interval, 0.879 to 0.975). The microRNA retained its diagnostic value in models after adjustment for age, sex, ejection fraction, and serum troponin level.ConclusionsAfter identifying a novel microRNA in mice and humans with myocarditis, we found that the human homologue (hsa-miR-Chr8:96) could be used to distinguish patients with myocarditis from those with myocardial infarction. (Funded by the Spanish Ministry of Science and Innovation and others.)

Comparative evaluation of empagliflozin, canagliflozin and sitagliptin cardioprotective effect in diabetic rats with experimental myocardial infarction

Comparative evaluation of empagliflozin, canagliflozin and sitagliptin cardioprotective effect in diabetic rats with experimental myocardial infarction

Therapeutic effects of CXCR4+ subpopulation of transgene‐free induced cardiosphere‐derived cells on experimental myocardial infarction

ObjectivesMyocardial infarction (MI) is the most predominant type of cardiovascular diseases with high mortality and morbidity. Stem cell therapy, especially cardiac progenitor cell therapy, has been proposed as a promising approach for cardiac regeneration and MI treatment. Previously, we have successfully generated cardiac progenitor‐like cells, induced cardiosphere (iCS), via somatic reprogramming. However, the genome integration characteristic of virus‐based reprogramming approach hampered their therapeutic applications due to the risk of tumour formation. In the current study, we aim to establish a safer iCS generation strategy with transgene‐free approaches.Materials and MethodsFour transgene‐free approaches for somatic reprogramming, including episome, minicircle, self‐replicative RNA, and sendai virus, were compared, from the perspective of cardiac progenitor marker expression, iCS formation, and cardiac differentiation. The therapeutic effects were assessed in the mouse model of MI, from the perspective of survival rate, cardiac function, and structural alterations.ResultsThe self‐replicative RNA approach produced more iCS, which had cardiomyocyte differentiation ability and therapeutic effects on the mouse model of MI with comparable levels with endogenous cardiospheres and iCS generated with retrovirus. In addition, the CXCR4 (C‐X‐C chemokine receptor 4) positive subpopulation of iCS derived cells (iCSDC) delivered by intravenous injection was found to have similar therapeutic effects with intramyocardial injection on the mouse model of MI, representing a safer delivery approach.ConclusionThus, the optimized strategy for iCS generation is safer and has more therapeutic potentials.

Intrapericardial administration of cardiosphere derived cells or their extracellular vesicles early after experimental myocardial infarction in swine: safe, easy but of limited effectiveness

Intrapericardial administration of cardiosphere derived cells or their extracellular vesicles early after experimental myocardial infarction in swine: safe, easy but of limited effectiveness

Potential therapeutic role of thioredoxin-1 in heart failure

Thioredoxin-1 (Trx-1), a 12 kDa protein, is a highly protective protein against myocardial infarction in murine model. Whether this protective phenomenon can be attributed to cardiomyocyte regeneration or survival, a consequence of the reduced levels of cellular ROS, inflammatory cytokines and/or protein oxidation, or to another phenomenon is not known. Thus, Trx-1 can be considered as a potential therapeutic molecule to treat heart failure. Nevertheless, its cleavage by two a-secretases leading to the truncated pro-inflammatory isoform, Trx-80, could compromise its therapeutic use. The aim of the project is to determine by which mechanism Trx-1 plays a cardioprotective role. For this purpose, we analyzed the impact of Trx-1, Trx-80 and Trx-mimetic peptide, CB3, corresponding to the catalytic site, on cultured neonatal mice cardiomyocytes and in vivo on adult mice with experimental myocardial infarction. To overexpress Trx-1 and Trx-80, we generated different AAV with a TnT cardiac chicken promoter which is specific to the cardiomyocytes. Infected cultured cardiomyocytes with AAV-Trx-1 reduced the intracellular level of ROS and the size of the cells. In contrast, cells infected with AAV-Trx80 increased the level of ROS. In addition, neither AAV-Trx1 nor AAV-Trx80 did show any significant effect on cell proliferation; while CB3 significantly increased cardiomyocytes proliferation in a dose-dependent manner. In vivo study showed that Trx-1 and CB3 improved cardiac functions such as ejection fraction, fractional shortening and thickness parietal wall. In contrast, AAV-Trx80 aggravated such parameters. In conclusion, our results showed that Trx-1 and its mimetic peptide seem to play a beneficial role on heart failure. Nevertheless, additional studies are needed to clarify the mechanism underlying such effect and identify other pathways.

Intrapericardial regenerative therapies in experimental subacute myocardial infarction. comparative study of microencapsulated versus free cdcs administration

Intrapericardial regenerative therapies in experimental subacute myocardial infarction. comparative study of microencapsulated versus free cdcs administration

Myeloid Cell‐Specific Epidermal Growth Factor Receptor (EGFR) Regulates the Immune Response in the Infarcted Heart

A mountain of evidence suggests paramount roles for myeloid cells in cardiac physiology. For one, these leukocytes have been reported to play major roles in the maintenance of functional and structural homeostasis. Additionally, following an injury, myeloid cell processes can enormously influence both short- and long-term remodeling and repair outcomes, ultimately informing heart failure. Given these significant roles, a lot of recent work has focused on examining exactly how these leukocytes might be regulated. Epidermal growth factor receptor (EGFR) is a tyrosine kinase receptor that is known to critically govern cell function through for instance proliferation, migration, and survival. Interestingly, recent reports suggest that EGFR regulates macrophage activation and function, however it is currently unknown if, and how EGFR might influence myeloid cell responses within the heart. Thus, our group has generated myeloid cell-specific EGFR knockout mice (EGFRmylKO) to determine the impact of such deletion on cardiac homeostasis and post injury outcomes. We hypothesize that myeloid cell-specific EGFR is a central regulator of cardiovascular inflammation, and is key in influencing post injury outcomes. To date, we have identified that in the absence of myeloid expressed EGFR, 12-16-week-old mice exhibit increased cardiomyocyte size and “fetal gene program” transcripts when compared to both age matched floxed EGFR (EGFRf/f) and LysM cre controls. Further, we have subjected EGFRmylKOand controls to experimental myocardial infarction (MI), and have observed decreased systolic function inEGFRmylKO. To begin understanding these phenotypes, we have analyzed basal and post injury cardiacmyeloid populations. We have observed that EGFRmylKO mice exhibit increased c-c chemokine receptor type2 (CCR2+) resident macrophages, and an increase in monocytes and macrophages 1 week following MI. Altogether, these results suggest novel roles for EGFR in the failing heart.