Rat Cardiomyoblasts Research Articles

Aloperine Regulates Inflammation, Apoptosis, and Autophagy in H9C2 Rat Cardiomyoblast Cells After Excessive Hypoxia

Myocardial infarction (MI) is a cardiovascular condition that leads to increased morbidity and mortality, impacting the quality of life of individuals. Aloperine (ALO), derived from Sophora alopecuroides L, has been recognized for its beneficial effects in treating various diseases by showcasing therapeutic properties. However, the precise protective mechanisms of ALO on hypoxia/reoxygenation (H/R) -induced damage in cardiomyocytes in vitro remain unclear. In this study, it was manifested that cell proliferation was weakened after H/R treatment, but this impact was offset after ALO treatment. Furthermore, cell apoptosis was heightened after H/R treatment, but this phenomenon was neutralized after ALO treatment. ALO relieved inflammation in H/R-treated H9C2 rat cardiomyoblast cells. Moreover, ALO strengthened autophagy in H/R-triggered H9C2 rat cardiomyoblast cells through enhancing the LC3II/LC3I level and the LC3B fluorescence intensity. Lastly, it was testified that ALO can rescue the weakened autophagy, the heightened cell apoptosis, and the augmented inflammation after CC treatment in H/R-mediated H9C2 rat cardiomyoblast cells. In conclusion, ALO regulated inflammation, apoptosis, and autophagy through AMPK/Nrf2 pathway in H9C2 rat cardiomyoblast cells after excessive hypoxia. This study suggested that ALO may be an underlying drug for MI therapy.

Lipid Emulsion Mitigates the Cardiotoxic Effects of Labetalol in Rat Cardiomyoblasts

Lipid emulsion has recently emerged as an effective agent for improving the cardiotoxicity of highly lipophilic drugs. However, its effect on cardiotoxicity induced by labetalol, a nonselective beta-blocker, remains unknown. In this study, we investigated the effects of lipid emulsion on the cardiotoxicity of labetalol in rat cardiomyoblasts and tried to decipher the underlying mechanisms. The effects of lipid emulsion on labetalol-induced changes in cell viability, expression of Bax/Bcl-2, cleaved caspase-3, and cleaved caspase-9, and phosphorylation of GSK-3β, Akt, and PI3K were examined. Lipid emulsion inhibited labetalol-induced decrease in cell viability, whereas LY294002, MK2206, and SB216763, the inhibitors of phosphoinositide 3-kinase (PI3K), Akt, glycogen synthase kinase-3β (GSK-3β), respectively, partially attenuated this restoration of cell viability. Lipid emulsion reversed the increase in expression of cleaved caspase-3, cleaved caspase-9, and Bax/Bcl-2 and decrease in the phosphorylation of GSK-3β, Akt, and PI3K by labetalol. Lipid emulsion and cyclosporin, a mitochondrial permeability transition pore (MPTP) inhibitor, reduced the labetalol-induced increase in the number of TUNEL-positive cells and promoted late-stage apoptosis. Overall, lipid emulsion inhibited apoptotic cell death caused by labetalol toxicity via the inhibition of intrinsic apoptotic pathway and MPTP in rat cardiomyoblasts, which appears to involve PI3K, Akt, and GSK-3β signaling pathways.

Lithium compromises the bioenergetic reserve of cardiomyoblasts mitochondria.

Lithium is used in the long-term treatment of bipolar disorder, exhibiting a beneficial effect on the neuronal cells. The concentration of lithium in the blood serum can vary and can easily approach a level that is related to cardiotoxic adverse effects. This is due to its narrow therapeutic index. In this study, we investigated the effect of higher than therapeutic dose of lithium. Rat cardiomyoblast cells were treated with 2 mM LiCl for 48h, after which the mitochondrial parameters of the cells were analyzed. Lithium exposure reduced maximal respiratory capacity by diminishing reserve respiratory capacity (RRC), linked to a decrease in complex I (NADH dehydrogenase) activity and elevated superoxide radical levels. In addition, lithium treatment altered the composition of cellular membranes, including mitochondrial cardiolipin, a lipid essential for mitochondrial function. These findings suggest that impaired complex I activity, oxidative stress, and cardiolipin depletion collectively impair the ability of cells to meet high energy demands.

Extractable organic matter from PM2.5 inhibits cardiomyocyte differentiation via AHR-mediated m6A RNA methylation.

An ever-increasing body of research has established a link between maternal PM2.5 exposure and congenital heart diseases in the offspring, but the underlying mechanisms remain elusive. We recently reported that activation of the aryl hydrocarbon receptor (AHR) by PM2.5 causes aberrant m6A RNA methylation, leading to cardiac malformations in zebrafish embryos. We hypothesized that PM2.5 can disrupt heart development by inducing m6A methylation changes through AHR in mammals. In this study, we observed that extractable organic matters (EOM) from PM2.5 significantly impaired cardiomyocyte differentiation in embryonic rat cardiomyoblasts H9c2. Importantly, EOM exposure reduced global m6A methylation levels, which was reversed by AHR inhibition. Moreover, AHR, activated by EOM directly promoted the transcription of the demethylase, FTO, leading to global m6A hypomethylation. Specifically, AHR-induced FTO overexpression decreased the m6A methylation levels of Nox4 mRNA, resulting in NOX4 overexpression and subsequent oxidative stress in EOM samples. We then demonstrated that oxidative stress contributes to the inhibition of cardiomyocyte differentiation by EOM through suppression of Wnt/β-catenin signaling. In summary, our findings indicate that AHR activation by PM2.5 directly enhances the expression of the demethylase, FTO, which increases NOX4 expression by reducing its m6A methylation. The oxidative stress caused by NOX4 overexpression inhibits Wnt/β-catenin signaling, thereby compromising cardiomyocyte differentiation.

Arrhythmogenic effects of DEHP exposure: insights into cardiac electrophysiology and myocardial cells

Abstract Introduction Hemodialysis patients, who are exposed to plasticizers through the hemodialysis circuit, face a high risk of cardiovascular disease (CVD). Plasticizers, such as the endocrine-disrupting compound Di(2-ethylhexyl) phthalate (DEHP), have emerged as potential contributors to CVD. This study explores the impact of DEHP on cardiac electrophysiology and myocardial cells, providing insights into its cardiotoxic effects. Methods We employed optical mapping techniques to assess cardiac electrophysiology in Langendorff-perfused rat hearts exposed to DEHP, comparing them to a control group. Additionally, we evaluated the effect of DEHP on cardiac muscle cells using H9C2 rat cardiomyoblasts. Results Prolonged DEHP exposure resulted in elevated heart rate, increased electrocardiographic variability, and higher low-frequency values, indicative of sympathetic nervous system overactivity. Action potential duration at APD80 increased, leading to greater action potential triangulation. Electrical alternans observed in the DEHP-treated group heightened the risk of arrhythmias. Single-cell analysis revealed severe mitochondrial damage, myocardial cell apoptosis, and disrupted calcium ion balance. Conclusion This study highlights DEHP's cardiotoxicity, suggesting its potential role in arrhythmogenesis and cardiac dysfunction. Environmental pollutants like DEHP warrant consideration as contributors to cardiovascular diseases, emphasizing the need for further research on preventive strategies.

Influence of Anesthetic Regimes on Extracellular Vesicles following Remote Ischemic Preconditioning in Coronary Artery Disease.

Remote ischemic preconditioning (RIPC) reduces ischemia-reperfusion injury in aortocoronary bypass surgery, potentially via extracellular vesicles (EVs) and their micro-RNA content. Clinical data implicate that propofol might inhibit the cardioprotective RIPC effect. This prospective, randomized study investigated the influence of different anesthetic regimes on RIPC efficacy and EV micro-RNA signatures. We also assessed the impact of propofol on cell protection after hypoxic conditioning and EV-mediated RIPC in vitro. H9c2 rat cardiomyoblasts were subjected to hypoxia, with or without propofol, and subsequent simulated ischemia-reperfusion injury. Apoptosis was measured by flow cytometry. Blood samples of 64 patients receiving anesthetic maintenance with propofol or isoflurane, along with RIPC or sham procedures, were analyzed, and EVs were enriched using a polymer-based method. Propofol administration corresponded with increased Troponin T levels (4669 ± 435.6 pg/mL), suggesting an inhibition of the cardioprotective RIPC effect. RIPC leads to a notable rise in miR-21 concentrations in the group receiving propofol anesthesia (fold change 7.22 ± 6.6). In vitro experiments showed that apoptosis reduction was compromised with propofol and only occurred in an EV-enriched preconditioning medium, not in an EV-depleted medium. Our study could clinically and experimentally confirm propofol inhibition of RIPC protection. Increased miR-21 expression could provide evidence for a possible inhibitory mechanism.

Synthesis and Biological Activity of Homohypotaurine Obtained by the Enzyme-Based Conversion of Homocysteine Sulfinic Acid Using Recombinant Escherichia Coli Glutamate Decarboxylase.

l-Homocysteine, formed from S-adenosyl methionine following demethylation and adenosine release, accumulates when the methionine recycling pathway and other pathways become impaired, thus leading to hyperhomocysteinemia, a biomarker in cardiovascular diseases, neurological/psychiatric disorders, and cancer. The partial oxidation of the l-homocysteine thiol group and its decarboxylation on C-alpha lead to the formation of l-homocysteinesulfinic acid (l-HCSA) and homohypotaurine (HHT), respectively. Both compounds are not readily available from commercial suppliers, which hinders the investigation of their biological activities. Herein, the chemical synthesis of l-HCSA, from l-homocystine, was the starting point for establishing the bio-based synthesis of HHT using recombinant Escherichia coli glutamate decarboxylase (EcGadB), an enzyme already successfully employed for the bio-based synthesis of GABA and its phosphinic analog. Prior to HHT synthesis, kcat (33.92 ± 1.07) and KM (38.24 ± 3.45 mM) kinetic constants were determined for l-HCSA on EcGadB. The results of our study show that the EcGadB-mediated synthesis of HHT can be achieved with good yields (i.e., 40% following enzymatic synthesis and column chromatography). Purified HHT was tested in vitro on primary human umbilical vein endothelial cells and rat cardiomyoblasts and compared to the fully oxidized analog, homotaurine (OT, also known as tramiprosate), in widespread pharmaceutical use. The results show that both cell lines display statistically significant recovery from the cytotoxic effects induced by H2O2 in the presence of HHT.

Abstract Tu131: Counteracting Cardiac Ischemia and Reperfusion Injury: the role of Sialidase Neu3

Coronary reperfusion procedures are crucial for restoring blood flow to the heart tissue after an acute myocardial infarction. However, they also lead to ischemia and reperfusion injury (IRI), which exacerbate the damage and promote heart failure. Despite the urgent need for cardioprotective strategies against IRI, none have been clinically implemented, emphasizing the need for a comprehensive understanding of the pathophysiology of IRI. Our research team found that sialidase Neu3, an enzyme responsible for the removal of sialic acid from glycosphingolipids, is modulated during IRI in vivo. Constitutive overexpression of Neu3 in rat cardiomyoblasts was shown to attenuate IRI through activation of the reperfusion injury salvage kinase (RISK) and HIF-1α signaling pathways. To further investigate the role of Neu3 in promoting cardioprotection, in this study we developed an inducible Neu3 overexpression model in human cardiac cells and mice. Inducible upregulation of Neu3 significantly improved cell resistance and reduced oxidative stress in AC16 cells exposed to IRI in vitro. These effects were attributed to Neu3-mediated maintenance of mitochondrial membrane potential, which was impaired in control cells. When looking at the upregulated genes exclusively in cells overexpressing the sialidase Neu3, RNAseq analysis revealed the predominant activation of MAP kinases typical of the RISK pathway. We also generated, for the first time, αMHC-Cre/LSL-Neu3 mice overexpressing Neu3 in an inducible and cardiomyocyte-specific manner. These mice showed no significant differences in cardiac morphology and functionality compared to wild-type animals. However, the Neu3-overexpressing mice exhibited a significant reduction in infarct size and improved cardiac functionality after surgical induction of IRI. These results suggest that Neu3 is a promising target for improving cardioprotection and attenuating the incidence and severity of myocardial infarction.

Elamipretide protects H9c2 Rat Cardiomyoblasts against Doxorubicin-Induced Disruption of Mitochondrial Quality Control by Restoration of Fusion and Fission Balance

Doxorubicin (DOX) has been used to treat malignant diseases for over 40 years. The main constraint to its clinical application is dose-dependent cardiotoxicity which is regarded as a major matter of concern that limits its medical usefulness. Mitochondrial dysfunction is considered the chief contributor to DOX-induced cardiotoxicity and it involves disruption of mitochondrial quality control, mainly impaired fusion, and enhanced fission processes. Compounds that specifically target the mitochondria and restore fusion and fission balance are considered a promising tool to protect or treat cardiomyopathy and heart failure and thus could be investigated as a novel strategy to alleviate DOX-induced cardiac toxicity, one of which is elamipretide (ELAM). In this study, MTT assay revealed that DOX induces a significant reduction in H9c2 cell viability which is both time and dose-dependent whereas ELAM has no significant effect on the viability of the relevant cells at most of the concentrations used. Additionally, western blot analysis showed a significant reduction in the expression of fusion protein MFN2 in the DOX-treated group compared to the control (p***< 0.001) whereas the fission protein DRP1 was significantly upregulated in DOX-treated cells compared to the control (p**< 0.01) and normalization of both proteins was achieved when 10 µM ELAM introduced 48-hour prior to DOX therapy. In conclusion, ELAM could exert an interesting cardioprotective role against DOX-induced cardiotoxicity by restoration of mitochondrial fusion and fission balance.

Implantable Patch of Oxidized Nanofibrillated Cellulose and Lysozyme Amyloid Nanofibrils for the Regeneration of Infarcted Myocardium Tissue and Local Delivery of RNA-Loaded Nanoparticles.

Biopolymeric implantable patches are popular scaffolds for myocardial regeneration applications. Besides being biocompatible, they can be tailored to have required properties and functionalities for this application. Recently, fibrillar biobased nanostructures prove to be valuable in the development of functional biomaterials for tissue regeneration applications. Here, periodate-oxidized nanofibrillated cellulose (OxNFC) is blended with lysozyme amyloid nanofibrils (LNFs) to prepare a self-crosslinkable patch for myocardial implantation. The OxNFC:LNFs patch shows superior wet mechanical properties (60MPa for Young's modulus and 1.5MPa for tensile stress at tensile strength), antioxidant activity (70% scavenging activity under 24h), and bioresorbability ratio (80% under 91 days), when compared to the patches composed solely of NFC or OxNFC. These improvements are achieved while preserving the morphology, required thermal stability for sterilization, and biocompatibility toward rat cardiomyoblast cells. Additionally, both OxNFC and OxNFC:LNFs patches reveal the ability to act as efficient vehicles to deliver spermine modified acetalated dextran nanoparticles, loaded with small interfering RNA, with 80% of delivery after 5 days. This study highlights the value of simply blending OxNFC and LNFs, synergistically combining their key properties and functionalities, resulting in a biopolymeric patch that comprises valuable characteristics for myocardial regeneration applications.

Cardioprotective anti-inflammatory activities of Artemisia lactiflora Wall. ex DC. extract and fractions in a rat cardiomyoblast (H9c2) model of inflammatory sepsis

Context: Sepsis is a progressive inflammatory response commonly caused by gram-negative bacteria via activation of the NF-κB-dependent pathway. Severe sepsis can cause cardiac dysfunction and increases the risk of death. Artemisia lactiflora is a Chinese medicinal plant that contains phenolics and flavonoids with probable anti-inflammatory activities. Aims: To investigate the anti-inflammatory activities of A. lactiflora leaves extract in a cardiac sepsis model. Methods: A. lactiflora leaves were extracted and fractioned using solvents of different polarities. The total phenolic and flavonoid content was quantified. The antioxidants were quantified in vitro using DPPH and ABTS radicals. The cytotoxicity of the extract and fractions was evaluated and calculated using the neutral red assay and curve-fitting analysis in cardiomyoblasts (H9c2). The anti-inflammatory activities of A. lactiflora were observed by treating H9c2 with extract and fractions in the presence of Escherichia coli. Expression of pro-inflammatory genes (TNF and IL6) and secretion of pro-inflammatory cytokines (TNF-α and IL-6) were measured by RT-qPCR and ELISA. Results: Extract and fractions of A. lactiflora contained noticeably high quantities of phenolics and flavonoids with considerably high anti-DPPH and anti-ABTS activities. Co-treatment with A. lactiflora extract and all fractions significantly downregulated the expression of TNF and IL6 as well as decreased the secretion of TNF-α and IL-6 (p<0.0001) compared with E. coli-stimulated cardiomyoblasts. The butanol fraction had the highest potency in reducing pro-inflammatory cytokine secretions in cardiomyoblasts under in vitro sepsis conditions. Conclusions: A. lactiflora leaf extract demonstrated therapeutic potential in a cardiac sepsis model by alleviating the inflammatory responses. This plant can potentially be developed as an alternative medicine for inflammation and sepsis.

Exploring the Efficacy Enhancement Mechanism of Qixue Shuangbu prescription after TCM processing for treating chronic heart failure by regulating ERK/Bcl-2/Bax/Caspases-3 signaling pathway

Qixue Shuangbu prescription (QSP) has been used for the treatment of chronic heart failure (CHF) with remarkable curative effect. Processed QSP (PQSP) could significantly improve the treatment of CHF after traditional Chinese medicine (TCM) processing. This study elucidated the underlying efficacy enhancement mechanism of QSP after TCM processing for treating CHF in vitro and in vivo. The injury of rat cardiomyoblast H9c2 cells was induced by anoxia/reoxygenation to mimic CHF state in vitro. Sixty Sprague-Dawley rats were used to established CHF model by intraperitoneally injecting doxorubicin (the accumulative dose 15 mg/kg). Biochemical examinations were performed in serum and cellular supernatant, respectively. Cardiac functions and histopathological changes were evaluated in CHF model rats. The protein and mRNA levels of ERK1/2, Bcl-2, Bax and Caspase-3 were evaluated by Western blot and RT-PCR, respectively. All above results of low dose crude QSP-treated group (L-CQSP), high dose CQSP-treated group (H-CQSP), low dose PQSP-treated group (L-PQSP), high dose PQSP-treated group (H-PQSP) were compared to systematically explore correlations between TCM processing and the efficacy enhancement for treating CHF of PQSP. Compared with the model group, the L-CQSP group showed significant improvement in cardiac function at 8th weeks, while no significant improvement in cardiomyocyte apoptosis and fibrosis. Both H-CQSP, L-PQSP and H-PQSP exerted beneficial therapeutic effects in injured H9c2 cardiomyocytes and CHF model rats. L-PQSP and H-PQSP significantly increased cell viability and the activity of SOD, decreased the activities of LDH, MDA and NO, up-regulated the expression of ERK1/2 and Bcl-2, down-regulated the expression of Bax and Caspase-3 compared to the same dosage of CQSP. The efficacy enhancement mechanism of PQSP after TCM processing for treating CHF was directly related to the regulation of ERK/Bcl-2/Bax/Caspases-3 signaling pathway.

Ginsenoside Rd Attenuates Myocardial Ischemia/Reperfusion Injury by Inhibiting Inflammation and Apoptosis through PI3K/Akt Signaling Pathway.

Myocardial ischemia/reperfusion (I/R) injury is the leading cause of death worldwide. Ginsenoside Rd (GRd) has cardioprotective properties but its efficacy and mechanism of action in myocardial I/R injury have not been clarified. This study investigated GRd as a potent therapeutic agent for myocardial I/R injury. Oxygen-glucose deprivation and reperfusion (OGD/R) and left anterior descending (LAD) coronary artery ligation were used to establish a myocardial I/R injury model in vitro and in vivo. In vivo, GRd significantly reduced the myocardial infarct size and markers of myocardial injury and improved the cardiac function in myocardial I/R injury mice. In vitro, GRd enhanced cell viability and protected the H9c2 rat cardiomyoblast cell line from OGD-induced injury GRd. The network pharmacology analysis predicted 48 potential targets of GRd for the treatment of myocardial I/R injury. GO and KEGG enrichment analysis indicated that the cardioprotective effects of GRd were closely related to inflammation and apoptosis mediated by the PI3K/Akt signaling pathway. Furthermore, GRd alleviated inflammation and cardiomyocyte apoptosis in vivo and inhibited OGD/R-induced apoptosis and inflammation in cardiomyocytes. GRd also increased PI3K and Akt phosphorylation, suggesting activation of the PI3K/Akt pathway, whereas LY294002, a PI3K inhibitor, blocked the GRd-induced inhibition of OGD/R-induced apoptosis and inflammation in H9c2 cells. The therapeutic effect of GRd in vivo and in vitro against myocardial I/R injury was primarily dependent on PI3K/Akt pathway activation to inhibit inflammation and cardiomyocyte apoptosis. This study provides new evidence for the use of GRd as a cardiovascular drug.

Involvement of Ferroptosis Induction and Oxidative Phosphorylation Inhibition in the Anticancer-Drug-Induced Myocardial Injury: Ameliorative Role of Pterostilbene.

Patients with cancer die from cardiac dysfunction second only to the disease itself. Cardiotoxicity caused by anticancer drugs has been emphasized as a possible cause; however, the details remain unclear. To investigate this mechanism, we treated rat cardiomyoblast H9c2 cells with sunitinib, lapatinib, 5-fluorouracil, and cisplatin to examine their effects. All anticancer drugs increased ROS, lipid peroxide, and iron (II) levels in the mitochondria and decreased glutathione peroxidase-4 levels and the GSH/GSSG ratio. Against this background, mitochondrial iron (II) accumulates through the unregulated expression of haem oxygenase-1 and ferrochelatase. Anticancer-drug-induced cell death was suppressed by N-acetylcysteine, deferoxamine, and ferrostatin, indicating ferroptosis. Anticancer drug treatment impairs mitochondrial DNA and inhibits oxidative phosphorylation in H9c2 cells. Similar results were observed in the hearts of cancer-free rats treated with anticancer drugs in vitro. In contrast, treatment with pterostilbene inhibited the induction of ferroptosis and rescued the energy restriction induced by anticancer drugs both in vitro and in vivo. These findings suggest that induction of ferroptosis and inhibition of oxidative phosphorylation are mechanisms by which anticancer drugs cause myocardial damage. As pterostilbene ameliorates these mechanisms, it is expected to have significant clinical applications.

Protective effect of colchicine on albumin glycation and cellular oxidative stress: Insights into diabetic cardiomyopathy.

The present work elucidates the role of colchicine (COL) on albumin glycation and cellular oxidative stress in diabetic cardiomyopathy (DCM). Human serum albumin (HSA) was glycated with methylglyoxalin the presence of COL (2.5, 3.75, and 5 µM), whereas positive and negative control samples were maintained separately. The effects of COL on HSA glycation, structural and functional modifications in glycated HSA were analyzed using different spectroscopical andfluorescence techniques. Increased fructosamine, carbonyl, and pentosidine formation in glycated HSA samples were inhibited in the presence of COL. Structural conformation of HSA and glycated HSA samples was examined by field emission scanning electron microscopy, circular dichroism, Fourier transform infrared, and proton nuclear magnetic resonance analyses, where COL maintained both secondary and tertiary structures of HSA against glycation. Functional marker assays included ABTS•+ radical scavenging and total antioxidant activities, advanced oxidative protein product formation, and turbidimetry, which showed preserved functional properties of glycated HSA in COL-containing samples. Afterward, rat cardiomyoblast (H9c2 cell line) was treated with glycated HSA-COL complex (400 μg/mL) for examining various cellular antioxidants (nitric oxide, catalase, superoxide dismutase, and glutathione) and detoxification enzymes (aldose reductase, glyoxalase I, andII) levels. All three concentrations of COL exhibited effective anti-glycation properties, enhanced cellular antioxidant levels, and detoxification enzyme activities. The report comprehensively analyzes the potential anti-glycation and properties of COL during its initial assessment.

Fludioxonil induces cardiotoxicity via mitochondrial dysfunction and oxidative stress in two cardiomyocyte models.

Fludioxonil (Flu) is a phenylpyrrole fungicide and is currently used in over 900 agricultural products globally. Flu possesses endocrine-disrupting chemical-like properties and has been shown to mediate various physiological and pathological changes, such as apoptosis and differentiation, in diverse cell lines. However, the effects of Flu on cardiomyocytes have not been studied so far. The present study investigated the effects of Flu on mitochondria in AC16 human cardiomyocytes and H9c2 rat cardiomyoblasts. Flu decreased cell viability in a water-soluble tetrazolium assay and mediated morphological changes suggestive of apoptosis in AC16 and H9c2 cells. We confirmed that annexin V positive cells were increased by Flu through annexin V/propidium iodide staining. This suggests that the decrease in cell viability due to Flu may be associated with increased apoptotic changes. Flu consistently increased the expression of pro-apoptotic markers such as Bcl-2-associated X protein (Bax) and cleaved-caspase 3. Further, Flu reduced the oxygen consumption rate (OCR) in AC16 and H9c2 cells, which is associated with decreased mitochondrial membrane potential (MMP) as observed through JC-1 staining. In addition, Flu augmented the production of mitochondrial reactive oxygen species, which can trigger oxidative stress in cardiomyocytes. Taken together, these results indicate that Flu induces mitochondrial dysregulation in cardiomyocytes via the downregulation of the OCR and MMP and upregulation of the oxidative stress, consequently resulting in the apoptosis of cardiomyocytes. This study provides evidence of the risk of Flu toxicity on cardiomyocytes leading to the development of cardiovascular diseases and suggests that the use of Flu in agriculture should be done with caution and awareness of the probable health consequences of exposure to Flu.

Cardiac tissue modeling using flow microsystems and nanofiber mats: Evaluating hypoxia-induced cellular and molecular changes

Myocardial cell regeneration research necessitates models that accurately represent heart tissues, especially in disease states. Our study unveils a unique Lab-on-a-chip system that combines polyurethane nanofiber mats, produced through solution-blown spinning, to simulate hypoxic conditions – a key factor in many heart diseases. This innovative microsystem's design includes specialized channels where hypoxia is achieved by flowing nitrogen over the culture chambers. We utilized two cell lines, human cardiomyocytes and rat cardiomyoblasts (H9c2), to assess the effects of this hypoxic environment on cell viability, morphology, and ATP levels. After 5 and 7 h of hypoxia exposure, H9c2 cells showed marked decreases in ATP levels. Additionally, there were pronounced reductions in the expression of cardiac function-related proteins such as MAP4K, TNNT2, SERCA, and SCN5A. This cutting-edge model allows for the simultaneous culture of myocardial cells in both hypoxic and normoxic conditions, positioning it as a pivotal tool for advances in regenerative medicine and cardiac tissue research. The observed impact of hypoxia on vital cardiac proteins expression in this system provides a deeper understanding of the mechanisms behind critical heart conditions, including myocardial infarction and heart failure.

Cardioprotective polyphenols from Geum japonicum var. chinense

Seven undescribed tannins, namely gejaponin A-G, and one dehydrodigallic acid derivative 3,4-dihydroxy-5-(3,4,5-trihydroxy-1-ethoxycarbonyl phenoxy)benzoic acid, together with eighteen known polyphenols were isolated from the 95% ethanol extract of the aerial part of Geum japonicum Thunb. var. chinense F. Bolle. Their structures were elucidated on the basis of comprehensive analysis of UV, IR, NMR, HRMS, and CD spectroscopy experiments. To evaluate their bioactivities, sixteen major compounds were selected to intervene in hydrogen peroxide (H2O2)-induced oxidative damage on H9c2 rat cardiomyoblasts. Some compounds demonstrated high activity in this assay, of which, the known compounds 16 and 21 exhibited strong protective effects against H2O2-induced injury in H9c2 rat cardiomyoblasts, with a comparable cardioprotective activity as that of the positive control trimetazidine, thereby revealing cardioprotective activities from G. japonicum var. chinense.

Epicardial tissue derived leptin promotes myocardial injury in metabolic syndrome rats through PKC/NADPH oxidase/ROS pathway

Abstract Background The epicardial adipose tissue (EAT) of metabolic syndrome (MetS) is abnormally accumulated with dysfunctional secretion of adipokines, closely relating to cardiac dysfunction. The adipokines leptin has been proven to induce cardiac fibroblasts collagen metabolism disorder in hypertensive left ventricular hypertrophy rats. Purpose The study was designed to identify the effects of EAT-derived leptin on the myocardium of MetS rats and explore the potential molecular mechanisms. Methods and results MetS rat model was established in eight-week-old male Wistar rats by 12 week high-fat diet. MetS rats exhibited increased leptin secretion from EAT, cardiac hypertrophy and diastolic dysfunction with preserved systolic function. The myocardium of MetS rats had abnormal structure and mitochondrial morphology, increased oxidative stress injury and inflammatory factors level, especially the subepicardial myocardium, which was correlated with the EAT-derived leptin level, but not the serum leptin (Figure 1). The EAT was separated from each group rats to prepare EAT-Conditioned Medium (EAT-CM). The H9C2 rat cardiomyoblasts were treated with EAT-CM or leptin, plus various signaling pathway inhibitors. EAT derived leptin from MetS rats promoted mitochondrial oxidative stress and dysfunction, induced mitochondrial pathway apoptosis and inhibited cell viability in H9C2 cardiomyoblasts via PKC/NADPH oxidase/ROS pathway. EAT derived leptin from MetS rats stimulated inflammation in H9C2 cardiomyocytes by promoting AP-1 nuclear translocation via PKC/NADPH oxidase/ROS pathway. Leptin promoted the interaction between p-p47phox and gp91phox in H9C2 cardiomyocytes via PKC, activating NADPH oxidase, increasing ROS generation, and inhibiting cell viability. Conclusions EAT derived leptin induces the MetS related myocardial injury though the following two cooperative ways via PKC/NADPH oxidase/ROS pathway: 1. Inducing mitochondrial pathway apoptosis by promoting mitochondrial oxidative stress and dysfunction; 2. Stimulating inflammation by promoting AP-1 nuclear translocation (Figure 2). The results reveal the potential molecular mechanisms of EAT in MetS related myocardial injury, providing novel insights for the further study of MetS related cardiovascular diseases.Figure 1Figure 2

Abstract 18622: The Role of MicroRNA-98 in the Context of Myocardial Ischemia-Reperfusion Injury During Late Pregnancy

BACKGROUND: We have shown that the late-pregnant (LP) rodent exhibits a higher susceptibility to myocardial ischemia-reperfusion injury (IRI) compared to non-pregnant (NP). The molecular mechanisms remain unclear. The dysregulation of multiple microRNAs (miRs) in IRI suggests their potential as promising targets for therapeutic interventions. Methods: Female Sprague-Dawley rats in both NP and LP states underwent occlusion of the left anterior descending coronary artery (LAD) for a duration of 45 minutes, followed by reperfusion for 3 hours or 24 hours. Expression of miR was assessed via fluorescent in situ hybridization. MicroRNA-microarray profiling was conducted on hearts of NP and LP rats subjected to IRI. Female H9c2 rat cardiomyoblast cells were transfected with miR mimics and inhibitors, and subjected to hypoxia/reoxygenation. Blood samples were obtained from NP, LP, and ischemic heart disease (IHD) patients. MiR98 inhibitor was administered at the initiation of reperfusion. Results: MicroRNA-microarray analysis revealed upregulation of microRNA-98-5p (miR-98) in LV of LP at baseline, and a further upregulation after IRI. The expression of Stat3 and Pgc-1α were decreased in LV of LP rats compared to NP rats upon IRI. Fluorescent in situ hybridization revealed expression of miR-98 in cardiomyocytes in NP rats, which was increased in LP rats. Overexpression of miR-98 in vitro in female H9c2 cells decreased Stat3 and Pgc-1α levels, and promoted apoptosis, oxidative stress, and inflammatory markers. MiR-98 inhibitor in LP rats at the onset of reperfusion reduced infarct size, apoptosis, oxidative stress, and inflammatory markers and was associated with upregulation of Stat3 and Pgc-1α. In humans, plasma miR-98 levels were significantly higher in healthy LP compared to healthy NP individuals and even higher in LP patients with IHD patients. CONCLUSIONS: We show the detrimental effects of miR-98 by promoting cardiomyocyte oxidative stress, inflammation, and apoptosis via its targets Stat3 and Pgc-1α in the context of late pregnancy. MiR-98 could be a novel cardio-protective strategy or biomarker in late pregnancy.