The mechanism of miR-525-5p derived from hypoxia and reoxygenation in H9c2 Cardiomyocytes

Ischemia-reperfusion injury (IRI) is associated with ischemic heart disease (IHD) which leads to patients a poor progression. According to Pubmed Datasets, we analyzed different gene and mRNA expressions in IHD patients with IRI. The relevant mRNA expression detected in H9C2 cells undergo hypoxia and reoxygenation, we selected and structured miR-525-5p gene mutation H9C2 cells, the results performed miR-525-5p mutated restored H9C2 metabolism of mitochondria which detected by relevant genes and proteins. At the same time, miR-525-5p silence resisted hypoxia and reoxygenation induced H9C2 cells apoptosis. All the results indicated miR-525-5p maybe protect H9C2 cells without hypoxia and reoxygenation induced injury through regulating the mitochondria metabolism.

Trehalose Ameliorates Diabetic Cardiomyopathy: Role of the PK2/PKR Pathway

Ample clinical case reports suggest a high incidence of cardiomyopathy in diabetes mellitus (DM). Recent evidence supports an essential role of trehalose (TLS) in cardiomyocyte survival signaling. Our previous study found that prokineticin2 (PK2) was involved in the process of diabetic cardiomyopathy (DCM). The present study examined the protective effects and mechanisms of TLS on DM-induced cardiomyocyte injury in mice and H9c2 cardiomyocytes. C57BL/6J mice were intraperitoneally injected with 50 mg·kg-1·d-1 streptozotocin for five consecutive days to establish an experimental diabetic model and then administered TLS (1 mg·g-1·d-1, i.p.) for two days every 4 weeks and given 2% TLS in drinking water for 24 weeks. Echocardiography, myocardial structure, apoptosis, pyroptosis, autophagy, and the PK2/PKR pathway were assessed. Cardiomyocytes exposed to high glucose (HG) were treated with TLS in the absence or presence of the PK2 antagonist PKRA7, and proteins involved in apoptosis, autophagy, and pyroptosis and the PK2/PKR pathways were evaluated using Western blot analysis. Diabetic mice demonstrated metabolic disorder, abnormal myocardial zymograms, and aberrant myocardial systolic and diastolic function, which were accompanied by pronounced apoptosis, pyroptosis, and dampened autophagy. TLS treatment relieved these effects. PK2 and receptor expressions were downregulated in diabetic mice, and TLS nullified this effect. PKRA7 eliminated the impact of TLS on cardiomyocytes. This evidence suggests that TLS rescues DM-induced myocardial function, pyroptosis, and apoptosis, likely via the PK2/PKR pathway.

Evaluating the affect of dimethyl sulfoxide on the viablity of H9C2 cardiomyocytes

Objective: The study was conducted to evaluate the affect of Dimethyl Sulfoxide (DMSO) concentration on the viability of H9C2 cells under the different cultural conditions. Methods: H9C2 cells were cultured under normal conditions and subjected to hypoxia/reoxygenation model. DMSOat the doses of 0,001÷10% (v/v) was added to the cultural medium during normal culture period and reoxygenation period. Cellular viability of the experimental groups was assessed by using CCK-8 kit. Results: The results indicated that the viability of H9C2 cardiomyocytes was stable in the different culture media supplied with DMSO at the doses of0,001÷0,5% (v/v). Meanwhile, supplementation of DMSO at the doses of1% and 2% significantly decreased the survival rate of H9C2 cells (v/v,p<0,05). Conclusion: The affect of DMSO on H9C2 cardiomyocytes is dose-dependant maner.

Hesperidin Extracted from Citrus reticulata Blanco Protects Cardiac Mitochondria Against Hypoxia/Reoxygenation Injury

This study was conducted to evaluate the protective effect of Hesperdin (Hes) extracted from Citrus reticulata Blanco on cardiac mitochondria in hypoxia/reoxygenation (HR) injury in vitro. Methods: H9C2 cardiomyocytes were cultured under normal (control), HR, and treatment conditions. The reactive oxygen species and calcium levels in experimental groups were analyzed by using suitable fluorescence kits. Results: The obtained results showed that the addition of Hes at dose of 0,01562 mg/mL sharply decreased the mitochondrial oxidative stress of H9C2 cells under HR conditions. In particular, Hes showed the remarkable efficiency in maintaing cellular calcium levels. In HR-exposed H9C2 cell group, the hydrogen peroxide and superoxide levels were highly increased compared to those in control group (1,54±0,06 and 1,74±0,38, p<0,05). HR also strongly induced the elevation of cytosolic Ca²⁺ and mitochondial Ca²⁺ of H9C2 cardiomyocytes with the values were 1,96±0,05% and 1,62±0,33 (ratio to control, p<0,05), respectively. Interestingly, post-hypoxic supplementation of Hes effectivelly abolished the negative incresement of these indicators with the lower levels of reactive oxygen species and the better modulation of Ca²⁺ homeostasis. Conclusion: The present results are pilot data on the effects of Hes in protecting cardiac mitochondria against HR injury.

Notoginsenoside R1 Protects Against High Glucose-Induced Cell Injury Through AMPK/Nrf2 and Downstream HO-1 Signaling

Notoginsenoside R1 (NGR1), the primary bioactive compound found in Panax notoginseng, is believed to have antihypertrophic and antiapoptotic properties, and has long been used to prevent and treat cardiovascular diseases. However, its potential role in prevention of diabetic cardiomyopathy remains unclear. The present study aimed to investigate the mechanism of NGR1 action in high glucose-induced cell injury. H9c2 cardiomyocytes were cultured in a high-glucose medium as an in-vitro model, and apoptotic cells were visualized using TUNEL staining. Expression of Nrf2 and HO-1 was measured using Western blotting or reverse transcription-quantitative PCR (RT-qPCR). The Nrf2 small interfering (si) RNA was transfected into cardiomyocytes using Opti-MEM containing Lipofectamine® RNAiMAX. NGR1 protected H9c2 cardiomyocytes from cell death, apoptosis and hypertrophy induced by high glucose concentration. Expression of auricular natriuretic peptide and brain natriuretic peptide was remarkably reduced in NGR1-treated H9C2 cells. Western blot analysis showed that high glucose concentration markedly inhibited AMPK, Nrf2 and HO-1, and this could be reversed by NGR1 treatment. However, the cardioprotective effect of NGR1 was attenuated by compound C, which reverses Nrf2 and HO-1 expression levels, suggesting that AMPK upregulates Nrf2 and HO-1 gene expression, protein synthesis and secretion. Transfection of H9C2 cells with Nrf2 siRNA markedly reduced the cardioprotective effect of NGR1 via reduced expression of HO-1. These results indicated that NGR1 attenuated high glucose-induced cell injury via AMPK/Nrf2 signaling and its downstream target, the HO-1 pathway. We conclude that the cardioprotective effects of NGR1 result from upregulation of AMPK/Nrf2 signaling and HO-1 expression in cardiomyocytes. Our findings suggest that NGR1 treatment might provide a novel therapy for diabetic cardiomyopathy.

Protective Effect of Fasudil on Hydrogen Peroxide-Induced Oxidative Stress Injury of H9C2 Cardiomyocytes

Objective. Oxidative damage is a pathological factor that causes cardiovascular damage in the clinic and is increasingly serious. This study focused on the effect of fasudil on H2O2-induced oxidative damage in cardiomyocytes. Materials and Methods. H9C2 cardiomyocytes were cultured in vitro and divided into three groups: control group (Con group), H2O2 treatment (H2O2 group), and fasudil and H2O2 cotreatment (H2O2+fasudil group). The content levels of LDH and MDA in the supernatant were detected, and the morphology of H9C2 cardiomyocytes was observed by light microscopy. 8-OHdG staining was observed by a fluorescence inversion microscope. Cell Counting Kit (CCK-8), western blotting, real-time polymerase chain reaction (RT-PCR), and enzyme-linked immunosorbent assay (ELISA) were used to investigate the effect of fasudil on the Rho/ROCK signaling pathway. Results. Our results showed that after H2O2 treatment, the H9C2 cardiomyocytes were irregular in shape and elliptical. But the morphology of the H2O2+fasudil group was similar to that of the Con group. The green fluorescence of the H2O2 group was significantly enhancer than that of the Con group, while the green fluorescence of the H2O2+fasudil group was weaker than those of the H2O2 group. By detecting the supernatant, it was found that the contents of LDH were significantly increased, and the contents of SOD and CAT in the H2O2 group were significantly decreased. And the expression of antioxidant indicators in the H2O2 group was significantly decreased by western blotting. The results of RT-PCR showed that SOD1 and SOD2 mRNA in the H2O2 group was significantly reduced, and the contents of GPX1 and GPX3 in the H2O2 group were significantly decreased by enzyme-linked immunosorbent assay (ELISA). The expression of ROCK1, ROCK2, and downstream phosphorylation of myosin phosphatase target subunit-1 (p-MYPT-1) was significantly increased in the H2O2 group, while fasudil inhibited the increase of ROCK1, ROCK2, and p-MYPT-1. Conclusions. Fasudil can inhibit the Rho/ROCK signaling pathway induced by H2O2 and reduce oxidative stress response, inhibit apoptosis, and improve antioxidant enzyme activity in H9C2 cardiomyocytes thereby delaying cell senescence.

Metoprolol Protects Against Arginine Vasopressin-Induced Cellular Senescence in H9C2 Cardiomyocytes by Regulating the Sirt1/p53/p21 Axis

Cardiomyocyte senescence is involved in the pathological mechanism of cardiac diseases. Metoprolol is a β1 receptor blocker used for the treatment of hypertension. Recent studies show that Metoprolol can protect cardiomyocytes against ischemia injury. The present study aims to investigate the protective effects of Metoprolol against arginine vasopressin (AVP)-induced cellular senescence in cultured cardiomyocytes. The cell proliferation assay and cytotoxicity lactate dehydrogenase assay showed that the highest tolerated dosage of Metoprolol in H9C2 cardiomyocytes was optimized as 10 µM. The enzyme-linked immunosorbent assay showed that Metoprolol significantly ameliorated the elevated level of the DNA oxidation product 8-hydroxy-2 deoxyguanosine. Metoprolol also decreased the percentage of senescence-associated β-galactosidase positive cells and improved the telomerase activity under AVP exposure. Moreover, treatment with Metoprolol ameliorated the decreased intracellular nicotinamide phosphoribosyltransferase activity, nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate (NAD+/NADPH) ratio, and Sirtuin1 activity in cardiomyocytes by AVP. Finally, Metoprolol was able to downregulate the AVP-induced expression of acetylated p53 and p21. Taken together, our data reveal that Metoprolol protected the cardiomyocytes from AVP-induced senescence.

Abstract 11972: Ivabradine Attenuates Hypoxia/Reoxygenation-Induced Excessive Autophagy in H9c2 Cardiomyocyte by Modulation of the PI3K/Akt/mTOR Pathway

Introduction: Despite recent advances in resuscitation techniques, the mortality associated with survival from cardiac arrest (CA) still remains low. Cardiovascular ischemia/reperfusion injury (IRI) is one of the primary pathophysiology involved. Hypothesis: We assessed the hypothesis that ivabradine could attenuate hypoxia/reoxygenation injury of H9c2 cardiomyocytes by inhibiting excessive autophagy through PI3K/Akt/mTOR Pathway. Methods: Cultured H9c2 were randomly divided into 3 groups: CON (normoxia), H/R (hypoxia reoxygenation) and IVA. The IVA was divided into 4 subgroups, in which H9c2 were treated with or without ivabradine(20μM or 100μM) or PI3-kinase inhibitor LY294002(10μM) for 12 hours and then subjected to 12 hours of hypoxia and 24 hours of reoxygenation. Hypoxia was achieved by a hypoxia chamber filled with 5%CO 2 and 95% N 2 at 37°C. Cell viability were measured with CCK-8 assay kits. Cell autophagy was assessed by transmission electron microscopy (TEM). The expressions of autophagy marker protein (LC3, Beclin-1), PI3K, Akt and mTOR were determined by Western-blot assay. Results: A decrease of cell viability and an increase formulation of autophagosomes /autophagy lysozymes occurred after H/R. Significant improvement was noted in cells treated with ivabradine compared to H/R(Figure 1). Ivabradine promoted pmTOR/mTOR expression and lower expressions of LC3II/LC3I and Beclin 1. LY294002 antagonized the effects of ivabradine on antophagy (Figure 2). Conclusions: Ivabradine could protect H9c2 against H/R injury via inhibiting excessive autophagy through PI3K/Akt/mTOR pathway.