Contractile Function Of Heart Research Articles

Overexpression of soluble epoxide hydrolase reduces post-ischemic recovery of cardiac contractile function

Cytochromes P450 can metabolize endogenous fatty acids, such as arachidonic acid, to bioactive lipids such as epoxyeicosatrienoic acids (EETs) that have beneficial effects. EETs protect hearts against ischemic damage, heart failure or fibrosis; however, their effects are limited by hydrolysis to less active dihydroxy oxylipins by soluble epoxide hydrolase (sEH), encoded by the epoxide hydrolase 2 gene (EPHX2, EC 3.3.2.10). Pharmacological inhibition or genetic disruption of sEH/EPHX2 have been widely studied for their impact on cardiovascular diseases. Less well studied is the role of increased EPHX2 expression, which occurs in a substantial human population that carries the EPHX2 K55R polymorphism or after induction by inflammatory stimuli. Herein, we developed a mouse model with cardiomyocyte-selective expression of human EPHX2 (Myh6-EPHX2) that has significantly increased total EPHX2 expression and activity. Myh6-EPHX2 hearts exhibit strong, cardiomyocyte-selective expression of EPHX2. EPHX2 mRNA, protein, and epoxide hydrolysis measurements suggest that Myh6-EPHX2 hearts have 12-fold increase in epoxide hydrolase activity relative to wild type (WT) hearts. This increased activity significantly decreased epoxide:diol ratios in vivo. Isolated, perfused Myh6-EPHX2 hearts were not significantly different from WT hearts in basal parameters of cardiac function; however, compared to WT hearts, Myh6-EPHX2 hearts demonstrated reduced recovery of heart contractile function after ischemia and reperfusion (I/R). This impaired recovery after I/R correlated with reduced activation of PI3K/AKT and GSK3β signaling pathways in Myh6-EPHX2 hearts compared to WT hearts. In summary, the Myh6-EPHX2 mouse line represents a novel model of cardiomyocyte-selective overexpression of EPHX2 that has detrimental effects on cardiac function.

MRI Quantification of Cardiac Structure and Function in Cardiomyopathy Patients.

Cardiac Magnetic Resonance Imaging (CMRI) is a quantitative technique that enables non-invasive assessment of heart structure and contractile function as well as the mechanisms underlying cardiovascular disease. Here we provide step-by-step instructions and imaging protocols for conducting cardiac MRI exam on the patients with cardiomyopathies. Our imaging protocols are specific to the 3Tesla magnetic field strength.

Integrin α4 Positive Subpopulation in Adipose Derived Stem Cells Effectively Reduces Infarct Size through Enhanced Engraftment into Myocardial Infarction.

The efficacy of adipose-derived stem cells (ASCs) on myocardial infarction is limited due to poor survival and engraftment. Integrin-mediated cell adhesion is a prerequisite for its survival and homing. ASCs expressed insufficient integrin α4, limiting their homing capacity. This study aims to characterize integrin α4＋ ASC subpopulation and investigate their therapeutic efficacy in myocardial infarction. We used fluorescence-activated cell sorting to harvest integrin α4＋ ASCs subpopulation, which were characterized in vitro and transplanted into myocardial infarction model. Positron emission tomography imaging were performed to measure infarction size. Cardiac cine magnetic resonance imaging was used to evaluate heart contractile function. Compared with the unfractionated ASCs, integrin α4＋ ASCs subpopulation secreted a higher level of angiogenic growth factors, migrated more rapidly, and exhibited a stronger anti-apoptotic capacity. Vascular cell adhesion molecule-1 was obviously up-regulated at 3 days after myocardial infarction, which interacted with integrin α4 receptor on the surface of ASCs to enhance the survival and adhesion. Thus, we implanted unfractionated ASCs or integrin α4＋ ASCs subpopulation into the 3-day infarcted myocardium. Integrin α4＋ ASCs subpopulation exhibited more robust engraftment into the infarcted myocardium. Integrin α4＋ ASCs subpopulation more effectively decreased infarct size and strengthen cardiac function recovery than did the unfractionated ASCs. Integrin α4＋ ASCs subpopulation is superior to unfractionated ASCs in ameliorating ischemic myocardial damage in animal model. Mechanistically, their more robust engraftment into the infarct area, higher migratory capacity and their increased release of paracrine factors contribute to enhanced tissue repair.

Abstract P3192: Prdm16 Regulates Cardiac Metabolic Genes Through Perm1

The heart is a metabolically demanding organ that requires significant amounts of energy to function properly, and even minor metabolic deficiencies during development can lead to heart failure. Cardiomyopathies are a group of conditions that affect the heart's contractile function, and PRDM16 deficiency is a primary cause of cardiomyopathies associated with 1p36 deletion syndrome in humans. Conditional deletion of Prmd16 in the heart causes a spectrum of cardiac phenotypes including left ventricular non-compaction, late-onset heart failure, and dilated cardiomyopathy. Still, the mechanisms underlying these cardiac phenotypes with loss of Prdm16 are not fully understood. We and others demonstrated that lack of Prdm16 in the heart causes alterations in fatty acid (FA) oxidation and oxidative phosphorylation (OXPHOS) gene expression. Further, we now show that Prdm16 cardiac deletion reduces the expression of key regulators of FA oxidation and OXPHOS genes including Perm1. Loss and gain of Prdm16 function in vitro confirmed a cell-autonomous regulation of Perm1 by Prdm16 in H9c2 rat cardiomyoblasts and neonatal rat ventricular myocytes (NRVMs). Prdm16 ChIP-sequencing analysis of embryonic hearts revealed direct binding of Prdm16 to the promoter of Perm1. Prdm16 binding to Perm1 promoter was further confirmed by ChIP-qPCR in H9c2 cells. Knockdown of Prdm16 in NRVMs reduced maximal mitochondrial respiration, which was rescued by over-expressing Perm1. Further, PERM1 mRNA was diminished in human induced pluripotent stem cells-derived cardiomyocytes (iPSC-CMs) derived from a patient with a PRDM16 mutation (Q187X). These results are evidence that PRDM16 is an upstream regulator of PERM1 in the heart.

Human ApoE2 Endows Stronger Contractility in Rat Cardiomyocytes Enhancing Heart Function

(1) Background: Apolipoprotein E (ApoE) is a critical plasma apolipoprotein for lipid transport and nonlipid-related functions. Humans possess three isoforms of ApoE (2, 3, and 4). ApoE2, which exhibits beneficial effects on cardiac health, has not been adequately studied. (2) Methods: We investigated the cardiac phenotypes of the humanized ApoE knock-in (hApoE KI) rats and compared to wild-type (WT) and ApoE knock-out (ApoE KO) rats using echocardiography, ultrasound, blood pressure measurements, histology strategies, cell culture, Seahorse XF, cardiomyocyte contractility and intracellular Ca2+ tests, and Western blotting; (3) Results: hApoE2 rats exhibited enhanced heart contractile function without signs of detrimental remodeling. Isolated adult hApoE2 cardiomyocytes had faster and stronger sarcomere contractility because of more mitochondrial energy generation and stimulation-induced fast and elevated intracellular Ca2+ transient. The abundant energy is a result of elevated mitochondrial function via fatty acid β-oxidation. The fast and elevated Ca2+ transient is associated with decreased sarcoplasmic reticulum (SR) Ca2+ ATPase (SERCA2) and increased expression of cardiac ryanodine receptor 2 (RyR2) conducting a potent Ca2+ release from SR.; (4) Conclusions: Our studies validated the association of polymorphic ApoEs with cardiac health in the rat model, and revealed the possible mechanisms of the protective effect of ApoE2 against heart diseases.

Comparative features of the immediate impact of manual therapy traction manipulations on the cardiorespiratory system of men and women

Purpose: the aim of this study was to determine the principal differences of changes in the cardiorespiratory system activity under the influence of traction manipulations in the thoracic spine of men and women. Material & Methods: the 26 adults were involved in the study, including 18 women aged 39.6±12.1 years and 8 men aged 36.3±8.3 years. All patients were diagnosed with osteochondrosis of the thoracic spine, which was confirmed by radiographic examination. The study of the cardiorespiratory system was conducted in the first procedure of SMT before and after the use of traction manipulations directly in the physician office. The integrated method of studying the cardiorespiratory system defined as spiroarteriocardiorhythmography (SACR) was used. It simultaneously records the heart rate, rhythms of systolic and diastolic pressure at each heartbeat and respiratory rhythms, which provides significant time savings to determine the functional state of the heart, vessels and respiration, as well as to identify the important parameters of their interaction. Results: characterizing the changes in the cardiorespiratory system as a whole under the influence of traction manipulations on the thoracic spine, it should be noted that men and women had some significant unidirectional changes in HR (min–1), CO (dm3), CI (dm3/m2), IH (n. u.), which are determined primarily by the decrease in HR (min–1) under the influence of traction manipulations. As to the men, the significant effects were more related to the impact on the contractile function of the heart, which was confirmed by the improvement of the electrical systole of the ventricles (QTC, s), the increase in the activity of the effects of the parasympathetic branch of the ANS on the cardiac rhythm (HF, ms2) and a certain increase in the stroke index within the normative values (SI, cm3/m2), then to the women the significant effects were more related to the influence on the breathing pattern and vascular tone. Thus, characteristic and positive effects in women can be considered a decrease in the variability of diastolic blood pressure in the very-low-frequency range (VLFDBP, mmHg2), which is combined with a decrease in the total power of diastolic pressure variability (TPDBP, mmHg2) and an increase in the total peripheral vascular resistance (GPVR, dyn/s/cm−5). Conclusions: summarizing the results of the impact of traction manipulations in the thoracic spine on the cardiorespiratory system of men and women, it can be stated that their effect is different and has features associated with the use of different mechanisms. For men, the predominant effect is on the heart contractile function, and for women it is on the respiratory system and autonomous regulation of vascular tone.

Early echocardiographic evaluation of right ventricular load adaptability after sequential combination treatment in pulmonary arterial hypertension.

Using the tricuspid annular plane systolic excursion (TAPSE)/pulmonary arterial systolic pressure (PASP) ratio as an index of right ventricular load adaptability, we aimed to evaluate early changes in right heart contractile function of patients with group1 pulmonary artery hypertension (PAH) after sequential combination PAH-specific therapy. Atotal of 49patients with group1 PAH and 31control participants were included in the study. The baseline clinical and echocardiographic data of the control and PAH group were compared. Subsequently, clinical and echocardiographic data of PAH patients before treatment and at 6months after PAH-specific treatment were analyzed. Asignificant increase in the TAPSE/PASP ratio was found in patients at 6months of PAH-specific treatment (0.25 ± 0.14; 0.33 ± 0.16, p < 0.001). Right atrial pressure (8 mm Hg [5-10]; 5 mm Hg [3-8], p < 0.001) and PASP (80.8 ± 30.6 mm Hg; 65.9 ± 25.7 mm Hg, p < 0.001) were significantly lower after sequential combination PAH-specific therapy. Negative correlations were found between the TAPSE/PASP ratio and N‑terminal pro-B-type natriuretic peptide (r = -0.524, p < 0.001), tricuspid regurgitation velocity (r = -0.749, p < 0.001), right atrial area (r = -0.298, p = 0.037), and right atrial pressure (r = -0.463, p = 0.001). In patients with group1 PAH, echocardiographic evaluation at the early stage of treatment (6months) shows asignificant improvement in the TAPSE/PASP ratio indicating right ventricular load adaptation. Comprehensive studies are needed on the routine use of the TAPSE/PASP ratio in the risk assessment of PAH patients.

Brain stem death induces pro-inflammatory cytokine production and cardiac dysfunction in sheep model

IntroductionOrgans procured following brain stem death (BSD) are the main source of organ grafts for transplantation. However, BSD is associated with inflammatory responses that may damage the organ and affect both the quantity and quality of organs available for transplant. Therefore, we aimed to investigate plasma and bronchoalveolar lavage (BAL) pro-inflammatory cytokine profiles and cardiovascular physiology in a clinically relevant 6-h ovine model of BSD. MethodsTwelve healthy female sheep (37–42 Kg) were anaesthetized and mechanically ventilated prior to undergoing BSD induction and then monitored for 6 h. Plasma and BAL endothelin-1 and cytokines (IL-1β, 6, 8 and tumour necrosis factor alpha (TNF-α)) were assessed by ELISA. Differential white blood cell counts were performed. Cardiac function during BSD was also examined using echocardiography, and cardiac biomarkers (A-type natriuretic peptide and troponin I were measured in plasma. ResultsPlasma concentrations big ET-1, IL-6, IL-8, TNF-α and BAL IL-8 were significantly (p < 0.01) increased over baseline at 6 h post-BSD. Increased numbers of neutrophils were observed in the whole blood (3.1 × 109 cells/L [95% confidence interval (CI) 2.06–4.14] vs. 6 × 109 cells/L [95%CI 3.92–7.97]; p < 0.01) and BAL (4.5 × 109 cells/L [95%CI 0.41–9.41] vs. 26 [95%CI 12.29–39.80]; p = 0.03) after 6 h of BSD induction vs baseline. A significant increase in ANP production (20.28 pM [95%CI 16.18–24.37] vs. 78.68 pM [95%CI 53.16–104.21]; p < 0.0001) and cTnI release (0.039 ng/mL vs. 4.26 [95%CI 2.69–5.83] ng/mL; p < 0.0001), associated with a significant reduction in heart contractile function, were observed between baseline and 6 h. ConclusionsBSD induced systemic pro-inflammatory responses, characterized by increased neutrophil infiltration and cytokine production in the circulation and BAL fluid, and associated with reduced heart contractile function in ovine model of BSD.

Overexpression of SERCA2a Alleviates Cardiac Microvascular Ischemic Injury by Suppressing Mfn2-Mediated ER/Mitochondrial Calcium Tethering.

Our previous research has shown that type-2a Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) undergoes posttranscriptional oxidative modifications in cardiac microvascular endothelial cells (CMECs) in the context of excessive cardiac oxidative injury. However, whether SERCA2a inactivity induces cytosolic Ca2+ imbalance in mitochondrial homeostasis is far from clear. Mitofusin2 (Mfn2) is well known as an important protein involved in endoplasmic reticulum (ER)/mitochondrial Ca2+ tethering and the regulation of mitochondrial quality. Therefore, the aim of our study was to elucidate the specific mechanism of SERCA2a-mediated Ca2+ overload in the mitochondria via Mfn2 tethering and the survival rate of the heart under conditions of cardiac microvascular ischemic injury. In vitro, CMECs extracted from mice were subjected to 6 h of hypoxic injury to mimic ischemic heart injury. C57-WT and Mfn2KO mice were subjected to a 1 h ischemia procedure via ligation of the left anterior descending branch to establish an in vivo cardiac ischemic injury model. TTC staining, immunohistochemistry and echocardiography were used to assess the myocardial infarct size, microvascular damage, and heart function. In vitro, ischemic injury induced irreversible oxidative modification of SERCA2a, including sulfonylation at cysteine 674 and nitration at tyrosine 294/295, and inactivation of SERCA2a, which initiated calcium overload. In addition, ischemic injury-triggered [Ca2+]c overload and subsequent [Ca2+]m overload led to mPTP opening and ΔΨm dissipation compared with the control. Furthermore, ablation of Mfn2 alleviated SERCA2a-induced mitochondrial calcium overload and subsequent mito-apoptosis in the context of CMEC hypoxic injury. In vivo, compared with that in wild-type mice, the myocardial infarct size in Mfn2KO mice was significantly decreased. In addition, the findings revealed that Mfn2KO mice had better heart contractile function, decreased myocardial infarction indicators, and improved mitochondrial morphology. Taken together, the results of our study suggested that SERCA2a-dependent [Ca2+]c overload led to mitochondrial dysfunction and activation of Mfn2-mediated [Ca2+]m overload. Overexpression of SERCA2a or ablation of Mfn2 expression mitigated mitochondrial morphological and functional damage by modifying the SERCA2a/Ca2+-Mfn2 pathway. Overall, these pathways are promising therapeutic targets for acute cardiac microvascular ischemic injury.

Short term methylphenidate treatment does not increase myocardial injury in the ischemic rat heart.

Methylphenidate is commonly used for the treatment of attention deficit hyperactivity disorder. The cardiovascular safety of methylphenidate has been a subject of debate with some studies indicating that methylphenidate increases the likelihood of experiencing a myocardial infarction. However, it is unknown whether methylphenidate worsens the extent of injury during an ischemic insult. The purpose of this study was to determine whether short term exposure to methylphenidate increases the extent of myocardial injury during an ischemic insult. Male and female rats received methylphenidate (5 mg/kg/day) or saline for 10 days by oral gavage. Hearts were subjected to 20 min of ischemia and 2 h of reperfusion on a Langendorff isolated heart apparatus on day 11. Cardiac contractile function was monitored via an intraventricular balloon and myocardial injury was assessed by triphenyltetrazolium chloride staining. Methylphenidate significantly increased locomotor activity in male and female rats, confirming absorption of this psychostimulant into the central nervous system. Male hearts had significantly larger infarcts than female hearts, but methylphenidate had no impact on infarct size or postischemic recovery of contractile function in hearts of either sex. These data indicate that methylphenidate does not increase the extent of injury induced by an ischemic insult.

Protective Effects of Polyphenols against Ischemia/Reperfusion Injury.

Myocardial infarction (MI) is a leading cause of morbidity and mortality across the world. It manifests as an imbalance between blood demand and blood delivery in the myocardium, which leads to cardiac ischemia and myocardial necrosis. While it is not easy to identify the first pathogenic cause of MI, the consequences are characterized by ischemia, chronic inflammation, and tissue degeneration. A poor MI prognosis is associated with extensive cardiac remodeling. A loss of viable cardiomyocytes is replaced with fibrosis, which reduces heart contractility and heart function. Recent advances have given rise to the concept of natural polyphenols. These bioactive compounds have been studied for their pharmacological properties and have proven successful in the treatment of cardiovascular diseases. Studies have focused on their various bioactivities, such as their antioxidant and anti-inflammatory effects and free radical scavenging. In this review, we summarized the effects and benefits of polyphenols on the cardiovascular injury, particularly on the treatment of myocardial infarction in animal and human studies.

Late‐In‐Life Treadmill‐Training Improves Autophagy, Protein Clearance, and Contractile Function in Mouse Hearts

Evidence exists that a progressive decline of the cellular quality control mechanism called macroautophagy occurs during the process of primary aging. This leads to the accumulation of protein aggregates (i.e., proteotoxicity) that would otherwise be transported to and degraded in the lysosome. Post‐mitotic cells like cardiomyocytes rely heavily on macroautophagy because of their inability to clear defective proteins via cell division. While voluntary wheel running improves cardiac autophagy, lessens cardiac proteotoxicity, and attenuates myocardial dysfunction in mice with desmin‐related cardiomyopathy (Bhuiyan et al., JCI, 2013), the ability for a physiological intervention to improve these indexes in aged mice is unknown. We hypothesized that late‐in‐life exercise training improves autophagy, protein aggregate clearance, and function that is otherwise dysregulated in hearts from old vs adult mice. As expected, 24‐month old male C57Bl6 mice (old) exhibited repressed autophagosome formation in the heart, myocardial protein aggregate accumulation, systolic and diastolic dysfunction, and reduced exercise capacity vs. 6‐month old (adult) mice (all p&lt; 0.05; n=10 per group) Separate cohorts of 21 month old mice completed a 10‐week progressive resistance / duration treadmill‐running program (old‐ETR) that improved (all p&lt;0.05): (i) body composition; (ii) maximal workload capacity; and (iii) soleus muscle citrate synthase activity vs. age‐matched sedentary mice (old‐SED). Of note, (iv) mRNA and protein expression of autophagy markers indicated trafficking of the autophagosome to the lysosome increased, (v) protein aggregate clearance improved, and (vi) contractile function was enhanced (all p&lt;0.05), in hearts from old‐ETR vs. old‐SED mice. Dietary maneuvers (e.g., caloric restriction, nutraceutical supplementation) and pharmacological interventions (e.g., rapamycin) are reported to elevate myocardial autophagy and mitigate / reverse age‐associated cardiac dysfunction. Here we show the first evidence that a physiological intervention i.e., late‐in‐life exercise training, improves autophagic flux, protein aggregate clearance, and contractile function in hearts from aged mice.Support or Funding InformationKL [APS STRIDE, UU Undergraduate Research Program (UROP)], JMC (UU Research Fellowship), SKP (AHA 17POST33670663), CR (APS UGRF, UROP), LT (UROP), SB (NIDDK R01‐DK‐098646‐01A1, R01‐DK‐099110, AHA 16GRNT30990018), JDS (AHA16GRNT31050004, NIH RO3AGO52848, NIHRO1HL141540).

Methylphenidate Does Not Hypersensitize the Rat Heart to Ischemic Injury

BackgroundMethylphenidate is commonly used for the treatment of attention deficit hyperactivity disorder. The cardiovascular safety of methylphenidate has been a subject of debate with some studies indicating that methylphenidate increases the likelihood of experiencing a myocardial infarction. However, it is unknown whether methylphenidate alters the extent of myocardial injury during an ischemic insult. Previous work demonstrated that a history of methamphetamine exposure increases infarct size and postischemic recovery of contractile function in the ischemic heart in a sex‐dependent manner. Methylphenidate and methamphetamine both increase synaptic concentrations of dopamine and norepinephrine, resulting in enhanced adrenergic and dopaminergic signaling. However, it is unknown whether methylphenidate also hypersensitizes the heart to ischemia. The purpose of this study was to determine whether methylphenidate increases the extent of myocardial injury during an ischemic insult.MethodsMale and female rats were treated with methylphenidate (5 mg/kg/day) or saline for 10 days. Hearts were subjected to a 20 min ischemic insult and 2 hours of reperfusion on a Langendorff isolated heart apparatus on day 11. Cardiac contractile function was monitored via an intraventricular balloon, and myocardial injury was assessed by triphenyltetrazolium chloride staining.ResultsMethylphenidate significantly increased locomotor activity in male and female rats. Male hearts had significantly larger infarcts than female hearts, but methylphenidate had no impact on infarct size or postischemic recovery of contractile function in hearts of either sex.ConclusionThese data indicate that methylphenidate does not increase myocardial sensitivity to ischemic injury.Support or Funding InformationThis work was supported by 1R15HL145546 to BRR.

Deletion of Neuropeptide Y Attenuates Cardiac Dysfunction and Apoptosis During Acute Myocardial Infarction.

Increasing neuropeptide Y (NPY) has been shown to be a risk factor for cardiovascular diseases. However, its role and mechanism in myocardial infarction (MI) have not yet been fully understood. H9c2 cells and neonatal rat ventricular myocytes with loss of function of NPY and rats with global knockout were used in this study. MI model of rats was induced by the ligation of left coronary artery, and the extent of MI was analyzed through echocardiographic, pathological, and molecular analyses. Our data demonstrated that NPY expression was significantly increased in MI rats and hypoxia/hydrogen peroxide (H2O2)-treated cardiomyocytes. At the same time, NPY-knockout rats exhibited a remarkable decrease in infarct size, serum lactate dehydrogenase activity, cardiomyocyte apoptosis, and caspase-3 expression and activity and a strong improvement in heart contractile function compared with MI rats. Meanwhile, NPY small interfering RNA (siRNA) inhibited the cell apoptosis in H2O2-treated H9c2 cells and hypoxia-treated neonatal rat ventricular myocytes. NPY deletion increased miR-499 expression and decreased FoxO4 expression in MI in vivo and in vitro. Moreover, NPY type 1 receptor antagonist BIBO3304 can reverse miR-499 decrease and FoxO4 increase in H2O2-induced cardiomyocytes. NPY siRNA inhibited cell apoptosis in H2O2-treated H9c2 cells that were reversed by miR-499 inhibitor. Additionally, FoxO4 was validated as the direct target of miR-499. Moreover, BIBO3304 and FoxO4 siRNA significantly increased the cell activity, inhibited the cell apoptosis, and decreased caspase-3 expression and activity in H2O2-treated cardiomyocytes that NPY presented the opposite effect. Collectively, deletion of NPY reduced myocardial ischemia, improved cardiac function, and inhibited cardiomyocyte apoptosis by NPY type 1 receptor–miR-499–FoxO4 axis, which provides a new treatment for MI.

4934Biventricular global and regional strain measured by cardiovascular magnetic resonance based tissue tracking

Abstract Background CMR based tissue tracking (CMR-TT), considered as a novel modality, provides additional insight into left and right ventricular (LV/RV) mechanical function and deformation. The vendor-specific reference values of global and regional strains for volunteers without history of cardiovascular disease are necessary as an important step in clinical routine to help detect early abnormality. Purpose To determine the reference value of LV/RV multi-dimensional global and segmental strains and diagnostic specificity of global longitudinal peak strain (GLS). Biventricular global and segmental radial, circumferential and longitudinal systolic peak strains (GRS, GCS, GLS and SRS, SCS, SLS) of 150 healthy adults in three age subgroups (G20–40, G41–60 and G61–80) were derived by post-hoc imaging software in standard steady-state free precession cine images acquired at 1.5T. LV strains were calculated with three-dimensional (3D) CMR-TT in the modified AHA 16-segment model via a short-axis stack and long axis 2-, 3-, 4-chamber cine images, and RV strains were generated with 2D CMR-TT via 4-chamber cine images. Results The reference values of LV global peak strains resulted as 44.4±13.0% for GRS, −17.0±2.7% for GCS, and −15.4±2.3% for GLS, respectively. RV-GLS was measured as −24.9±5.1%. Global and segmental strains might differ between males and females. Females showed significant age-associated difference of LV global peak strains (P&lt;0.05) as the opposite of males (Figure 1). Females also presented higher magnitude of LV global peak strains than males in the eldest group G61–80 (P&lt;0.05). Unlike LV, no age-associated difference of RV-GLS was detected in both gender groups. However, females showed less negative RV-GLS than males in G20–40 and more negative RV-GLS than males older than 40 years old (P&lt;0.05). The local discrepancy of biventricular SRS, SCS and SLS was observed. It seemed that LV mid-cavity played a more essential role on LV shortening (more negative SCS and SLS) than wall thickening (smaller SRS) compared with base and apex. RV basal and mid SLS, derived from segment 1–4, was more negative than apical SLS derived from segment 5–6. The specificity of LV- and RV-GLS cut-off value (mean value+1.96*standard deviation) generated from the vendor-, age- and gender-specific reference value in evaluating heart contractile function reached 97.3% and 94.7%, respectively. Conclusions Considering the vendor-, gender- and age-associated difference of biventricular global strains, specific reference values need to be established to facilitate the wide application of strain in clinical routine. Meanwhile, segmental strains are also fundamental for detecting local abnormality of myocardial deformation.

PM2.5-induced ADRB2 hypermethylation contributed to cardiac dysfunction through cardiomyocytes apoptosis via PI3K/Akt pathway

BackgroundLong-term exposure to fine particulate matter (PM2.5) can causally contribute to progression of atherosclerosis, risk of ischemic heart disease and death, but the underlying mechanism is little known. Since DNA methylation impacts the process of heart disease, it might be useful in exploring potential mechanistic pathways linking PM2.5 exposure and heart disease. ObjectivesHere, we investigated the PM2.5-induced ADRB2 hypermethylation and the involving epigenetic mechanism of PM2.5-induced cardiomyocytes apoptosis and cardiac dysfunction. Methods and resultsIn vitro, PM2.5 markedly augmented cardiotoxicity including oxidative damage and apoptosis in cardiomyocytes AC16 as well as epigenetic alteration. DNA methylation profiling revealed a significant gene-ADRB2 was involved in the cardiac relative GO and KEGG pathways. Methylation chip and Bisulfite Sequencing PCR (BSP) both identified the hypermethylation status of ADRB2 which encodes β2-Adrenergic receptor (β2AR). Mechanistic study showed ADRB2 hypermethylation-induced down-regulation of β2AR inhibited PI3K/Akt and then activated Bcl-2/BAX and p53 pathway in AC16. The transgenic cell lines showed over-expression of ADRB2 weakened the PM2.5-induced cardiomyocytes apoptosis in opposite way, but was augmented by PI3K inhibitor (LY294002). In vivo, echocardiography showed the heart contractile function was decreased after SD rats intratracheal instillation of PM2.5 for 30 days. The myocardial interstitial edema, myocardial gap expansion and myofibril disorder in PM2.5 treated group were observed in rats heart tissue. What's more, basal expression of β2AR and VEGFR2 decreased in heart tissue as the dosage of PM2.5 increasing, meanwhile PM2.5 markedly attenuated PI3K/Akt pathway followed by augmented Bcl-2/BAX and p53 pathway, thus caused a greater number of TUNEL positive cardiomyocytes resulted in cardiac dysfunction in vivo. ConclusionsPM2.5 exposure could cause the myocardial ADRB2 hypermethylation and activate the β2AR/PI3K/Akt pathway, resulted in PM2.5-induced cardiomyocytes apoptosis and cardiac dysfunction. Our study suggested that the ADRB2 demethylation or ADRB2/β2AR activation may serve as a potential pathway to prevent cardiac dysfunction induced by PM2.5 exposure.

Abstract 17122: Cardioprotection With Proangiogenic Nanomaterials Formulated With CHIR99021 and FGF1

Introduction: We aimed at to investigate whether activation of both FGF1 and Wnt1 synergistically enhances angiogenesis and render the cardioprotection in hearts with post infarction LV remodeling. Materials and methods: CHIR99021 (a Wnt1 activator) and FGF1 were encapsulated into poly lactic-co-glycolic acid nanoparticles (CHIR99021/FGF1-NPs). Ischemic heart models were generated in C57BL/6 mice or Yorkshire swine by ligation of the left anterior descending coronary. The mice were randomly divided into 6 groups: Myocardial infarction (MI) Only (n=11), MI with nanoparticles (CHIR99021 or/and FGF1 loaded) injection (n=12, each), MI with non-loaded nanoparticles injection (n=11) and Sham group (n=10). The swine were divided into 3 groups: ischemic reperfusion injury (IRI) (n=4), IRI with CHIR99021/FGF-NPs injection (n=4) and Sham group (n=4). Left ventricle function 4 week after surgery were evaluated by Echocardiography. Cell proliferation was assessed via immunostaining in ischemic hearts and in cultivated human umbilical vein endothelial cells (HUVECs) and Human vascular smooth muscle cells (HVSMCs) using the following markers: Ki67, Brdu, PH3, and Aurora B. Apoptosis was determined with TUNEL staining. Cardiac fibrosis was evaluated via Sirius red and Fast green staining (mice) and magnetic resonance imaging (swine). Results: CHIR99021/FGF1-NPs treatment attenuated fibrosis and preserved heart contractile function in mice and swine models of postinfarction LV remodeling. The proportion of cells that expressed cell cycle markers (Ki67; BrdU; Aurora B and PH3) was significantly greater in CHIR99021+FGF1 treatment group than CHIR99021, FGF1 and PBS treatment group. The proportion of apoptotic cells was significantly smaller in CHIR99021+FGF1 treatment group than in groups of control, VEGF, CHIR99021, or FGF1 treatment alone. Conclusions: CHIR99021 and FGF synergistically activate cell cycle and reduce apoptosis, which accompanied by a significant improvement of cardiac function.

Ex Vivo Cardiotoxicity of Antineoplastic Casiopeinas Is Mediated through Energetic Dysfunction and Triggered Mitochondrial-Dependent Apoptosis.

Casiopeinas are a group of copper-based antineoplastic molecules designed as a less toxic and more therapeutic alternative to cisplatin or Doxorubicin; however, there is scarce evidence about their toxic effects on the whole heart and cardiomyocytes. Given this, rat hearts were perfused with Casiopeinas or Doxorubicin and the effects on mechanical performance, energetics, and mitochondrial function were measured. As well, the effects of Casiopeinas-triggered cell death were explored in isolated cardiomyocytes. Casiopeinas III-Ea, II-gly, and III-ia induced a progressive and sustained inhibition of heart contractile function that was dose- and time-dependent with an IC50 of 1.3 ± 0.2, 5.5 ± 0.5, and 10 ± 0.7 μM, correspondingly. Myocardial oxygen consumption was not modified at their respective IC50, although ATP levels were significantly reduced, indicating energy impairment. Isolated mitochondria from Casiopeinas-treated hearts showed a significant loss of membrane potential and reduction of mitochondrial Ca2+ retention capacity. Interestingly, Cyclosporine A inhibited Casiopeinas-induced mitochondrial Ca2+ release, which suggests the involvement of the mitochondrial permeability transition pore opening. In addition, Casiopeinas reduced the viability of cardiomyocytes and stimulated the activation of caspases 3, 7, and 9, demonstrating a cell death mitochondrial-dependent mechanism. Finally, the early perfusion of Cyclosporine A in isolated hearts decreased Casiopeinas-induced dysfunction with reduction of their toxic effect. Our results suggest that heart cardiotoxicity of Casiopeinas is similar to that of Doxorubicin, involving heart mitochondrial dysfunction, loss of membrane potential, changes in energetic metabolites, and apoptosis triggered by mitochondrial permeability.

Therapeutic Benefit and Gene Network Regulation by Combined Gene Transfer of Apelin, FGF2, and SERCA2a into Ischemic Heart.

Despite considerable advances in cardiovascular disease treatment, heart failure remains a public health challenge. In this context, gene therapy appears as an attractive approach, but clinical trials using single therapeutic molecules result in moderate benefit. With the objective of improving ischemic heart failure therapy, we designed a combined treatment, aimed to simultaneously stimulate angiogenesis, prevent cardiac remodeling, and restore contractile function. We have previously validated IRES-based vectors as powerful tools to co-express genes of interest. Mono- and multicistronic lentivectors expressing fibroblast growth factor 2 (angiogenesis), apelin (cardioprotection), and/or SERCA2a (contractile function) were produced and administrated by intramyocardial injection into a mouse model of myocardial infarction. Data reveal that combined treatment simultaneously improves vessel number, heart function parameters, and fibrosis prevention, due to FGF2, SERCA2a, and apelin, respectively. Furthermore, addition of SERCA2a in the combination decreases cardiomyocyte hypertrophy. Large-scale transcriptome analysis reveals that the triple treatment is the most efficient in restoring angiogenic balance as well as expression of genes involved in cardiac function and remodeling. Our study validates the concept of combined treatment of ischemic heart disease with apelin, FGF2, and SERCA2a and shows that such therapeutic benefit is mediated by a more effective recovery of gene network regulation.

Abstract 21413: Molecular Basis of Maternal Obesity Induced Fetal Cardiac Contractile Dysfunction

One third of the women at reproductive age are overweight or obese in US. Epidemiological studies in humans and studies on animals have shown that obesity during pregnancy ( i.e. maternal obesity, MO) increases incidences of cardiovascular diseases in offspring. Uterus environment is essential for fetal cardiac development and MO as a stress condition in uterus could program cardiovascular disease in prenatal and postnatal offspring. However, the mechanisms of the origin and development of MO-induced cardiovascular disease later in life remain unclear. For this purpose, we use sheep (sharing many similarities with human pregnancy) as a model to study the impact of MO on fetal heart contractile function. Previously, we have demonstrated that MO impaired fetal sheep cardiomyocyte contractility by reducing the peak shortening and velocity of shortening/relengthening and prolonged the time to peak shortening/relengthening. We also found that MO disrupted the calcium homeostasis in fetal cardiomyocytes by increasing intracellular Ca 2+ level and inducing the calcium insensitivity in the cell. In current study, we found that MO increased the phosphorylation of protein kinase A (PKA) as well as the phosphorylation of Ca 2+ /calmodulin-dependent protein kinase II (CaMKII), which further promoted phosphorylation level of ryanodine receptor type 2 (Ryr2) at Ser2808 and Ser2814 respectively. Expression level of FKBP12.6, a key protein interacting with Ryr2 for calcium releasing, was upregulated in MO fetal myocardium. On the other hand, MO reduced expression of myosin heavy chain in fetal myocardium. Moreover, the cardiac troponin T and troponin I expression level was upregulated in MO fetuses, whereas MO downregulated the expression of troponin C in fetal myocardium. Taken together, our findings suggest that increased CaMKII and PKA phosphorylation of Ryr2 plays a critical role in the development of MO-induced sarcoplasmic reticulum Ca 2+ leak in fetal cardiomyocytes. Furthermore, our data indicate that the change in expression levels of myosin heavy chain and troponin C, I and T is the cause of calcium insensitivity and contractile dysfunction in MO fetal cardiomyocytes. Our studies have provided a fundamental molecular basis of MO programmed heart disease.