Rat Cardiomyoblasts Research Articles

Apigenin reduce lipoteichoic acid-induced inflammatory response in rat cardiomyoblast cells.

Infective endocarditis is caused by Streptococcus sanguinis present in dental plaque, which can induce inflammatory responses in the endocardium. The present study depicts research on the properties of apigenin in embryonic mouse heart cells (H9c2) treated with lipoteichoic acid (LTA) obtained from S.sanguinis. Interleukin-1β and cyclooxygenase (COX)-2 expression were detected by reverse transcriptase polymerase chain reaction. In addition, western blot assays and immuno-fluorescence staining were used to assess translocation of nuclear factor kappa beta (NF-κB), degradation of IκB, as well as activity of the mitogen activated protein kinases: extracellular signal-regulated kinase (ERK)1/2, p38, and c-Jun N-terminal kinase (JNK). Effect of apigenin on cell viability was equally assessed in other experimental series. Our results showed that apigenin blocked activation of ERK, JNK, and p38 in cardiomyocytes treated with LTA in a dose-dependent fashion. Moreover, apigenin showed no cytotoxic effects; it blocked NF-κB translocation and IκB degradation. Our findings suggested that apigenin possessed potential value in the treatment of infectious endocarditis.

Matricellular protein CCN1 mediates doxorubicin-induced cardiomyopathy in mice

Doxorubicin (DOX) is an effective chemotherapeutic agent however its clinical use is limited by its cumulative cardiotoxicity. Matricellular protein CCN1 mediates work-overload-induced cardiac injury. We aimed to assess the role of CCN1 in DOX-associated cardiomyopathy. Here we discovered CCN1 expression in the myocardium 1 day after DOX treatment (15 mg/kg; i.p.) in mice. Whereas CCN1 synergizes with Fas ligand (FasL) to induce cardiomyocyte apoptosis, we found that FasL was also induced by DOX in the heart. To assess the function of CCN1 in vivo, knockin mice (Ccn1dm/dm) expressing an β6β1-binding defective CCN1 mutant were treated with a single dose of DOX (15 mg/kg; i.p.). Compared with wild-type mice, Ccn1dm/dm mice were resistant to DOX-induced cardiac injury and dysfunction 14 days after injection. Using rat cardiomyoblast H9c2 cells, we demonstrated that DOX induced reactive oxygen species accumulation to upregulate CCN1 and FasL expression. CCN1 mediated DOX cardiotoxicity by engaging integrin β6β1 to promote p38 mitogen-activated protein kinase activation and the release of mitochondrial Smac and HtrA2 to cytosol, thereby counteracting the inhibition of XIAP and facilitating apoptosis. In summary, CCN1 critically mediates DOX-induced cardiotoxicity. Disrupting CCN1/β6β1 engagement abolishes DOX-associated cardiomyopathy in mice.

340. Cell Penetrating Peptide Can Improve the Efficacy of Mitochondrial Transfer

Cell-based therapies for organ regeneration are currently emerging as a new promising approach to treat various diseases, including cardiovascular and neurodegenerative diseases. However, the mechanism supporting these therapeutic effects remains poorly understood. Several recent studies suggest that the intercellular transfer of organelles, including mitochondria, might contribute to these regenerative responses.Mitochondria are considered cellular “power plants” because they largely synthesize the universal energy “currency” of the cells, i.e., adenosine triphosphate (ATP). Mitochondrial dysfunction is associated with many diseases, including metabolic and neurodegenerative disorders. In vitro experiments revealed that mitochondrial DNA (mtDNA)-depleted mammalian cells recovered aerobic respiration after intercellular mitochondrial transfer from intact cells. The therapeutic potential of mitochondrial transfer was supported by an in vivo study conducted on rabbit model of myocardial infarction. Direct injection of autologous mitochondria into the ischemic heart considerably improved post-infarct cardiac functions. Mitochondria dysfunction also plays central role in the pathogenesis of ischemia reperfusion injury and subsequent cardiomyocytes death. The beneficial effect of mitochondria replenishment for damaged cells and tissues has been reported recently.Our previous studies demonstrated that the mitochondrial transfer could occur by simple co-culture of mammalian cells with isolated mitochondria. We assessed the impact of the transfer on the mitochondrial function in the recipient cells. The mechanism of mitochondrial internalization was investigated using endocytosis inhibitors. We showed that mammalian cells engulfed isolated mitochondria by macropinocytosis, which survived in heteroplasmy state and functioned to generate ATP in recipient cells. However, the internalization for isolated mitochondria remains inefficient to apply as a clinical therapeutic strategy.Here, we report the use of TAT, which is cell penetrating peptide derived of human immunodeficiency virus, dextran complexes (TAT-DEX) to enhance the cellular uptake of exogenous mitochondria and improve the protective effect of mitochondria replenishment on rat neonatal cardiomyocytes (NRCM) from IR injury in vitro. TAT-DEX modification significantly neutralized surface negative charge in mitochondria isolated from the human endometrium-derived mesenchymal cells and H9c2 rat cardiomyoblast. TAT-DEX modified mitochondria isolated from H9c2 showed a significantly higher level of cellular uptake. Compared with control mitochondria, co-incubation of TAT-DEX modified mitochondria with NRCM during IR significantly reduced IR-induced reactive oxygen species production and apoptosis in NRCM. These results indicate that surface modification of isolated mitochondria at the molecular level can improve the efficiency of cellular uptake of exogenous mitochondria, and enhanced mitochondrial internalization into cardiomyocytes may improve the potential effect of mitochondria replenishment therapy in myocardial IR injury.

Secreted frizzled related protein 1 protects H9C2 cells from hypoxia/re-oxygenation injury by blocking the Wnt signaling pathway.

BackgroundIn animal models, secreted frizzled related protein 1 (Sfrp1) inhibition of the Wnt signaling pathway is beneficial because Sfrp1 reduces myocardial apoptosis and prevents heart failure. The mechanisms mediating the cellular survival effect of Sfrp1 has not been completely elucidated. The present study was designed to investigate the possible protective actions of Sfrp1 on cardiac muscle cells using an in vitro model of ischemia/reperfusion, and to evaluate the possible involvement of the Wnt signaling pathway.MethodsWe used a recombinant AAV9 vector to deliver the Sfrp1 gene into H9C2 rat cardiomyoblasts and adopted an in vitro model of ischemia/reperfusion. Cell vitality was measured by CKK-8 and the trypan blue exclusion assay. Western blot was used to evaluate the expression of Dvl-1, β-catenin, c-Myc, Bax, and Bcl-2. Flow cytometry analysis of cardiomyocyte apoptosis was performed.ResultsWe confirmed that Sfrp1 significantly increased cell viability (assayed by trypan blue and CKK-8) and decreased apoptosis (assayed by flow cytometry analysis and the Bax/Bcl-2 ratio). These effects were partly attributable to the ability of Sfrp1 to down-regulate Wnt signaling pathway (assayed by Western blot to evaluate the expression of Dvl-1, β-catenin, and c-Myc). Indeed, reactivation of the Wnt signaling pathway activity with the specific activator, Licl, reduced Sfrp1-induced cardioprotection during hypoxia and reoxygenation.ConclusionsThe present study demonstrated that Sfrp1 directly protected H9C2 cells from hypoxia and reoxygenation-induced reperfusion injury and apoptosis through inhibition of the Wnt signaling pathway, and added new mechanistic insight regarding the cardioprotective role of Sfrp1 on ischemic damage.Electronic supplementary materialThe online version of this article (doi:10.1186/s12944-016-0240-5) contains supplementary material, which is available to authorized users.

Steroidal saponins from Chlorophytum deistelianum

Phytochemical investigation of the aerial parts of Chlorophytum deistelianum led to the isolation of four previously undescribed steroidal saponins called chlorodeistelianosides A–D with five known ones. Their structures were established mainly by extensive 1D and 2D NMR spectroscopic techniques and mass spectrometry as (25R)-3β-[(β-d-glucopyranosyl-(1→3)-[α-l-rhamnopyranosyl-(1→4)]-β-d-xylopyranosyl-(1→3)-[β-d-glucopyranosyl-(1→2)]-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl)oxy]-5α-spirostan-12-one, (24S,25S)-24-[(β-d-glucopyranosyl)oxy]-3β-[(β-d-glucopyranosyl-(1→2)-[β-d-xylopyranosyl-(1→3)]-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl)oxy]-5α-spirostan-12-one, (25R)-26-[(β-d-glucopyranosyl)oxy]-2α-hydroxy-22α-methoxy-5α-furostan-3β-yl β-d-glucopyranosyl-(1→2)-[β-d-xylopyranosyl-(1→3)]-β-d-glucopyranosyl-(1→4)-β-d-galactopyranoside, and (25R)-26-[(β-d-glucopyranosyl)oxy]-3β-[(β-d-glucopyranosyl-(1→2)-[β-d-xylopyranosyl-(1→3)]-β-d-glucopyranosyl-(1→4)-β-d-galactopyranosyl)oxy]-5α-furost-20(22)-en-12-one. Cytotoxicity of most compounds was evaluated against one human cancer cell line (SW480) and one rat cardiomyoblast cell line (H9c2). Among them, three known spirostane-type glycosides exhibited cytotoxicity on both cell lines with IC50 ranging from 8 to 10μM.

Differential Effects of Colchicine on Cardiac Cell Viability in an in vitro Model Simulating Myocardial Infarction

Objectives: We aimed to examine the effects of colchicine, currently in clinical trials for acute myocardial infarction (AMI), on the viability of cardiac cells using a cell line model of AMI. Methods: HL-1, a murine cardiomyocyte cell line, and H9C2, a rat cardiomyoblast cell line, were incubated with TNFα or sera derived from rats that underwent AMI or sham operation followed by addition of colchicine. In another experiment, HL-1/H9C2 cells were exposed to anoxia with or without subsequent addition of colchicine. Cell morphology and viability were assessed by light microscopy, flow cytometry and Western blot analyses for apoptotic markers. Results: Cellular viability was similar in both sera; however, exposing both cell lines to anoxia reduced their viability. Adding colchicine to anoxic H9C2, but not to anoxic HL-1, further increased their mortality, at least in part via enhanced apoptosis. Under any condition, colchicine induced detachment of H9C2 cells from their culture plates. This phenomenon did not apply to HL-1 cells. Conclusions: Colchicine enhanced cardiomyoblast mortality under in vitro conditions mimicking AMI and reduced their adherence capability. HL-1 was not affected by colchicine; nevertheless, no salvage effect was observed. We thus conclude that colchicine may not inhibit myocardial apoptosis following AMI.

Scutellarin protects cardiomyocyte ischemia–reperfusion injury by reducing apoptosis and oxidative stress

AimsIschemic heart disease is a leading cause of death and disability worldwide. Despite recent advances, there is no effective therapy for preventing myocardial ischemia–reperfusion (I/R) injury. In this study, we aimed to examine the therapeutic effect of scutellarin, a flavone isolated from the traditional Chinese medicine Scutellaria barbata and Erigeron breviscapus, on cardiomyocyte I/R injury. Main methodsNeonatal rat cardiomyoblast cells H9C2 were used to study the role of scutellarin in cardiomyocyte injury. I/R injury was induced by 2h of hypoxia plus glucose and serum deprivation, followed by 6-hour recovery. Cardiomyocyte damage was evaluated by the release of pro-inflammatory cytokines and creatine kinase (CK), apoptosis, and cell proliferation. Oxidative responses were assessed by reactive oxygen species (ROS) production, MDA generation, SOD expression, and mitochondrial membrane potential detection. Activation of JAK2/STAT3 signaling and expression of pro- or anti-survival molecules were detected by Western blot. Key findingsI/R injury increased the release of CK as well as pro-inflammatory cytokines TNFα, IL-1β, IL-6, and IL-8 from cardiomyocytes. ROS, MDA, and apoptosis were enhanced in cardiomyocytes underwent I/R injury, while cell proliferation, mitochondrial membrane potential, SOD expression were reduced. Scutellarin treatment dose-dependently suppressed I/R injury-induced pro-inflammatory cytokine and CK release, oxidative response, loss of mitochondrial membrane potential, and enhanced cell proliferation and anti-oxidant SOD expression. Further analysis suggests scutellarin promotes JAK/STAT3 activation and expression of pro-survival proteins Bcl2, VEGF, MMP2, and MMP9. Pro-apoptotic molecules Bax and caspase-3 were suppressed by scutellarin. SignificanceWe identified a previously unrecognized pathway by which scutellarin protects myocardial I/R injury. Scutellarin modulates I/R injury-induced oxidative stress and apoptosis probably by enhancing JAK2/STAT3 pro-survival signaling.

Metformin Protects H9C2 Cardiomyocytes from High-Glucose and Hypoxia/Reoxygenation Injury via Inhibition of Reactive Oxygen Species Generation and Inflammatory Responses: Role of AMPK and JNK.

Metformin is a first-line drug for the management of type 2 diabetes. Recent studies suggested cardioprotective effects of metformin against ischemia/reperfusion injury. However, it remains elusive whether metformin provides direct protection against hypoxia/reoxygenation (H/R) injury in cardiomyocytes under normal or hyperglycemic conditions. This study in H9C2 rat cardiomyoblasts was designed to determine cell viability under H/R and high-glucose (HG, 33 mM) conditions and the effects of cotreatment with various concentrations of metformin (0, 1, 5, and 10 mM). We further elucidated molecular mechanisms underlying metformin-induced cytoprotection, especially the possible involvement of AMP-activated protein kinase (AMPK) and Jun NH(2)-terminal kinase (JNK). Results indicated that 5 mM metformin improved cell viability, mitochondrial integrity, and respiratory chain activity under HG and/or H/R (P < 0.05). The beneficial effects were associated with reduced levels of reactive oxygen species generation and proinflammatory cytokines (TNF-α, IL-1α, and IL-6) (P < 0.05). Metformin enhanced phosphorylation level of AMPK and suppressed HG + H/R induced JNK activation. Inhibitor of AMPK (compound C) or activator of JNK (anisomycin) abolished the cytoprotective effects of metformin. In conclusion, our study demonstrated for the first time that metformin possessed direct cytoprotective effects against HG and H/R injury in cardiac cells via signaling mechanisms involving activation of AMPK and concomitant inhibition of JNK.

Discovering Antioxidant Molecules in the Archaea Domain: Peroxiredoxin Bcp1 from Sulfolobus solfataricus Protects H9c2 Cardiomyoblasts from Oxidative Stress.

Peroxiredoxins (Prxs) are ubiquitous thiol peroxidases that are involved in the reduction of peroxides. It has been reported that prokaryotic Prxs generally show greater structural robustness than their eukaryotic counterparts, making them less prone to inactivation by overoxidation. This difference has inspired the search for new antioxidants from prokaryotic sources that can be used as possible therapeutic biodrugs. Bacterioferritin comigratory proteins (Bcps) of the hyperthermophilic archaeon Sulfolobus solfataricus that belong to the Prx family have recently been characterized. One of these proteins, Bcp1, was chosen to determine its antioxidant effects in H9c2 rat cardiomyoblast cells. Bcp1 activity was measured in vitro under physiological temperature and pH conditions that are typical of mammalian cells; the yeast thioredoxin reductase (yTrxR)/thioredoxin (yTrx) reducing system was used to evaluate enzyme activity. A TAT-Bcp1 fusion protein was constructed to allow its internalization and verify the effect of Bcp1 on H9c2 rat cardiomyoblasts subjected to oxidative stress. The results reveal that TAT-Bcp1 is not cytotoxic and inhibits H2O2-induced apoptosis in H9c2 cells by reducing the H2O2 content inside these cells.

Follistatin-like 1 protects cardiomyoblasts from injury induced by sodium nitroprusside through modulating Akt and Smad1/5/9 signaling

Cardiac cell apoptosis provoked by excessive sodium nitroprusside (SNP) toxicity, a potent vasodilator, limited its clinical application. Effective means for protection against SNP-induced cardiotoxicity would be highly needed. This study investigated the effects of Follistatin-like 1 (FSTL1) on the injury induced by SNP in rat cardiomyoblast H9c2 cells. First, expression of FSTL is attenuated following SNP treatment. SNP challenge significantly increases cardiac cell death, which is attenuated by FSTL1 pretreatment. Additionally, knockdown of endogenous FSTL1 enhances SNP-induced cell apoptosis. Furthermore, FSTL1 pretreatment partially inhibits SNP-induced NO generation. LY294002 and BMP4 completely abolish cytoprotective role of FSTL1 against SNP challenge, indicating both activation of Akt and inhibition of BMP/Smad1/5/9 signaling are involved in this cellular process. Lastly, FSTL1-mediated cytoprotection is independent of Smad2/3 signaling, as SB525334 fails to remove its protective role. Taken together, these results indicated that FSTL1 protects the SNP-induced injury in cardiac H9c2 cells through, at least in part, the activation of Akt and inhibition of Smad1/5/9 signaling.

Evaluation of the Cytotoxic Effect of Tissue Glue (Octyl 2-Cyanoacrylate) on H9C2 Cardiomyoblast Cells Using Extract Dilution Assay

Background: Recently, Tissue Glue or Octyl 2-Cyanoacrylate (OCA) has been extensively used in cardiac surgeries as surgical adhesives to replace sutures. Since the binder is in contact with live tissues, its tissue compatibility and non-cytotoxicity have major effect on enhancing the healing process. Objectives: The purpose of this study was to evaluate the cytotoxicity of OCA on rat cardiomyoblast cell (H9C2) using MTT assay. Materials and Methods: Cells were cultured in the presence of various concentrations of the OCA extract. Then, morphological changes of the cultured cells were observed by light microscopy and their cytotoxicity by MTT assay. The morphology quality of the cells and their quantity were examined after 24- hour incubation up to 72 hours. Data were analyzed statistically by the ANOVA. Results: The results showed that the percentage of survived cells amount of extract dilution ratio (1:4; 1:2; 1) were 80.4%; 79.6%, 77.5% respectively. Analysis of statistical test results does not show any significant differences between the optical density of the extract dilutions, and the control group indicating; consequently it has no significant cytotoxicity effect on the cells. Conclusions: The outcome of this study is that the OCA has no toxic effect on H9C2 cells.

MicroRNA-145 repairs infarcted myocardium by accelerating cardiomyocyte autophagy.

We investigated whether microRNA-145 (miR-145) has a cardioprotective effect in a rabbit model of myocardial infarction (MI) and in H9c2 rat cardiomyoblasts. Rabbits underwent 30 min of coronary occlusion, followed by 2 days or 2 wk of reperfusion. Control microRNA (control group; 2.5 nmol/kg, n = 10) or miR-145 (miR-145 group, 2.5 nmol/kg, n = 10) encapsulated in liposomes was intravenously administered immediately after the start of reperfusion. H9c2 rat cardiomyoblasts were transfected with miR-145. The MI size was significantly smaller in the miR-145 group than in the control group at 2 days and 2 wk post-MI. miR-145 had improved the cardiac function and remodeling at 2 wk post-MI. These effects were reversed by chloroquine. Western blot analysis showed that miR-145 accelerated the transition of LC3B I to II and downregulated p62/SQSTM1 at 2 days or 2 wk after MI, but not at 4 wk, and activated Akt in the ischemic area at 2 days after MI. miR-145 inhibited the growth of H9c2 cells, accelerated the transition of LC3B I to II, and increased phosphorylated Akt in the H9c2 cells at 2 days after miR-145 transfection. Antagomir-145 significantly abolished the morphological change, the transition of LC3B I to II, and the increased phosphorylated Akt induced by miR-145 in H9c2 cells. We determined fibroblast growth factor receptor substrate 2 mRNA to be a target of miR-145, both in an in vivo model and in H9c2 cells. In conclusion, post-MI treatment with miR-145 protected the heart through the induction of cardiomyocyte autophagy by targeting fibroblast growth factor receptor substrate 2.

Endogenous C1-inhibitor production and expression in the heart after acute myocardial infarction

Complement activation contributes significantly to inflammation-related damage in the heart after acute myocardial infarction. Knowledge on factors that regulate postinfraction complement activation is incomplete however. In this study, we investigated whether endogenous C1-inhibitor, a well-known inhibitor of complement activation, is expressed in the heart after acute myocardial infarction. C1-inhibitor and complement activation products C3d and C4d were analyzed immunohistochemically in the hearts of patients who died at different time intervals after acute myocardial infarction (n=28) and of control patients (n=8). To determine putative local C1-inhibitor production, cardiac transcript levels of the C1-inhibitor-encoding gene serping1 were determined in rats after induction of acute myocardial infarction (microarray). Additionally, C1-inhibitor expression was analyzed (fluorescence microscopy) in human endothelial cells and rat cardiomyoblasts in vitro. C1-inhibitor was found predominantly in and on jeopardized cardiomyocytes in necrotic infarct cores between 12h and 5days old. C1-inhibitor protein expression coincided in time and colocalized with C3d and C4d. In the rat heart, serping1 transcript levels were increased from 2h up until 7days after acute myocardial infarction. Both endothelial cells and cardiomyoblasts showed increased intracellular expression of C1-inhibitor in response to ischemia in vitro (n=4). These observations suggest that endogenous C1-inhibitor is likely involved in the regulation of complement activity in the myocardium following acute myocardial infarction. Observations in rat and in vitro suggest that C1-inhibitor is produced locally in the heart after acute myocardial infarction.

P66Shc signaling is involved in stress responses elicited by anthracycline treatment of rat cardiomyoblasts.

The adaptor protein p66Shc modulates cellular redox status integrating oxidative stress with mitochondrial stress responses. Upon oxidative stress, p66Shc is translocated to mitochondria or mitochondria-associated membranes in a multi-step process, resulting in locally increased reactive oxygen species production. This signaling pathway is believed to be important in the context of drug-induced organ toxicity. The use of anthracyclines as anticancer agents is limited due to a dose-dependent and cumulative toxicity resulting in cardiomyopathy. Treatment with the anthracycline doxorubicin (DOX) results in a dose-dependent and cumulative cardiotoxicity which is mediated, at least in part, by increased oxidative stress. In the present study, we investigated for the first time whether p66Shc signaling is activated during DOX treatment of the rat cardiomyoblast H9c2 cell line. We further tested whether the transcriptional factor FoxO3a, which activates target genes responsible for apoptosis and cell cycle arrest, is also involved in p66Shc-dependent redox signaling pathway. Our results suggest that DOX treatment induces p66Shc protein up-regulation specifically in nuclear fractions. Increased nuclear expression of FoxO3a was also detected in H9c2 cells after DOX treatment. Treatment with the antioxidant and protein kinase C (PKC-β) inhibitor hispidin decreased DOX-induced activation of caspase 9 and p66Shc alterations. Taking together, we hypothesize that p66Shc signaling is involved in the activation of stress/toxicity responses elicited by the treatment of H9c2 cells with DOX. Hence, the selective inhibition of this redox pathway may be a promising therapeutic approach to circumvent DOX cardiotoxicity.

Subcellular localization of anthracyclines in cultured rat cardiomyoblasts as possible predictors of cardiotoxicity.

SummaryIn this study, we compared the cellular uptake, intracellular localization and cytotoxicity of two groups of anthracycline derivatives in cultured H9c2(2-1) rat cardiomyoblasts. The first group consisted of doxorubicin (DOX) and two of its derivatives containing a formamidino group (–N = CH–N<) at the C-3′ position with a morpholine (DOXM) or a hexamethyleneimine (DOXH) ring. The second group consisted of daunorubicin (DRB) and its derivatives containing a morpholine (DRBM) or a hexamethyleneimine (DRBH) ring. DOXH and DRBH were taken up by cardiomyoblasts more efficiently than estimated for other tested anthracyclines. The cellular uptakes of DOXM and DRBM were reduced compared to those of the parent compounds. Applied structural modifications of DOX and DRB influenced the subcellular localization of the tested derivatives. DOX and DOXH were localized primarily in nuclei, whereas the other anthracyclines were found in the nuclei and cytoplasm. The percentages of the compounds that accumulated in the nuclei were 80.2 and 54.2 % for DOX and DOXH, respectively. The lowest nuclear accumulation values were observed for DRBM (19.9 %), DRBH (21.9 %) and DOXM (23.7 %). The ability of anthracyclines to accumulate in the nuclei correlated with their DNA binding constants (r = 0.858, P = 0.029). A correlation was found between the accumulation of the tested anthracyclines in the nuclei of cardiomyoblasts and their cardiotoxicity in vivo, which was observed in our previous study. We suggest that cytotoxicity and the anthracycline accumulation level in the nuclei of cultured cardiomyoblasts could be used for early prediction of their cardiotoxicity.

Molecular In Vivo Imaging Using a Noninvasive Cardiac-Specific MLC-2v Promoter Driven Dual-Gene Recombinant Lentivirus Monitoring System.

BackgroundOur study aimed to demonstrate the feasibility of using the sodium/iodide symporter (NIS) to monitor vascular endothelial growth factor (VEGF165) expression in vivo.MethodsWe constructed a recombinant lentivirus plasmid with the MLC-2v promoter driving the sodium/iodide symporter (NIS) reporter gene linked to the VEGF165 gene. Expression of NIS and VEGF gene were identified by Western blot. On days 2 and 54, 99mTc-MIBI imaging was used to evaluate changes in myocardial ischemia. Noninvasive 125I micro-SPECT/CT imaging was used to assess the expression of NIS reporter gene dynamically over the next 2 months.ResultsWestern blot analysis showed that both NIS and VEGF165 were highly expressed in rat cardiomyoblast H9C2 cells transduced with Lenti-MLC-2v-NIS--VEGF165. 125I micro-SPECT/CT reporter imaging showed higher uptake in mouse myocardium transduced with Lenti-MLC-2v-VEGF165-IRES-NIS. NIS expression peaked on day 1 after transduction followed by a progressive decline to negligible levels by day 21. On day 1, mean 125I activity value in group 1 was higher than that in group 2 (P<0.05). The mean 125I activity value in group 3 was statically lower than that in group 1 and 2 (P<0.01). On day 60, 125I uptakes in test and positive control groups became very low, and no significant differences in the mean 125I activity values were detected between group 1 and group 2 (P = 0.531 > 0.05). In group 1 (test group), 99mTc-MIBI SPECT/CT revealed improvements in perfusion and wall thickening in the apical anterior wall. Mean IOD values of NIS and CD34 were significantly higher in group 1 than group 3 (P<0.05). Our study proved mean I-125 uptake was significantly correlated with mean IOD value of NIS and CD34 (P<0.05).ConclusionThis study demonstrates the feasibility of using the NIS gene to monitor VEGF165 expression in a mouse myocardial ischemia model.

Abstract 263: Therapeutic Potential of a Novel Necrosis Inhibitor in Myocardial Ischemia-reperfusion Injury

Background: Reperfusion, although essential for salvage of ischemic myocardium, paradoxically causes a wide variety of injuries. Opening of mitochondrial permeability transition pore (mPTP) and Ca 2+ overload contribute to myocardial ischemia-reperfusion (I/R) injury. We aimed to investigate the protective role of a novel necrosis inhibitor (NecroX-7; NecX) against myocardial I/R injury, using in vitro and in vivo models. Methods and Results: In H9C2 rat cardiomyoblasts exposed to hypoxia-reoxygenation stress, the main mechanism of cell death was not apoptosis but necrosis, which was prevented mainly by NecX, the necrosis inhibitor, but not by Z-VAD-fmk, the apoptosis inhibitor. The protective effect of NecX was based on its potent ROS scavenging activity, especially on mitochondrial ROS which is one of the major inducers of mPTP opening. NecX preserved mitochondrial membrane potential, mitochondrial structure, through prevention of Ca 2+ influx and inhibition of the opening of mPTP. Inhibition of necrosis by NecX was accompanied by reduction of phospho-p38 MAPK and phospho-JNK, and decrease of HMGB1. Using Sprague-Dawley rats exposed to myocardial ischemia for 45 minutes followed by reperfusion, we compared therapeutic efficacies of NecX and Ciclosporin A (CsA) with 5% dextrose (control), each administrated 5 minutes before reperfusion. NecX markedly inhibited myocardial necrosis, reduced fibrotic area and attenuated the release of cardiac enzymes, compared to dextrose and CsA. Additionally, NecX preserved systolic function and prevented pathologic dilatory remodeling of left ventricle. Conclusion: The novel necrosis inhibitor has a significant protective effect against myocardial I/R injury, indicating that it is a promising candidate for cardioprotective adjunctive measure on top of reperfusion therapy. Clinical implication: We are trying to translate this experimental data into patients. A phase I clinical trial confirmed the safety profiles of NecX [NCT01737424] and a phase II trial for STEMI patients (NEXsteMI trial) is ongoing [NCT02070471].

Abstract 115: A Decrease in Mitochondrial, but Not Cytosolic, Iron Protects Against Cardiac Ischemia-reperfusion Damage Through a Reduction in Ros

Introduction: Iron is essential for the activity of several cellular proteins, but excess free iron can cause cellular damage through production of reactive oxygen species (ROS). Iron accumulation in mitochondria, the major site of cellular iron homeostasis, leads to cardiomyopathy. However, it is not known whether a reduction in baseline mitochondrial iron (as opposed to iron in other cellular compartments) can protect against ischemia-reperfusion (I/R) injury in the heart. We hypothesized that since mitochondria are the major site of iron homeostasis and that mitochondrial iron can lead to oxidative damage, a reduction in mitochondrial iron at baseline would be sufficient to protect against I/R injury. Results: Transgenic (TG) mice with cardiomyocyte-specific overexpression of the mitochondrial iron export protein ATP-binding cassette (ABC)-B8 had significantly lower mitochondrial iron in the heart than nontransgenic (NTG) littermates at baseline, but their cardiac function and the expression of key antioxidant systems were similar to NTG littermates. In response to I/R, TG mice displayed significantly less apoptosis and lipid peroxidation products and better preserved cardiac function than NTG littermates, suggesting that a reduction in mitochondrial iron protects against I/R injury. To confirm these results, we next took a pharmacological approach to assess the effects of a reduction in mitochondrial vs cytosolic iron on the response to I/R using 2,2’-bipyridyl (BPD, a mitochondria-accessible iron chelator) and deferoxamine (DFO, an iron chelator that can only reduce cytosolic iron). Mice pretreated with BPD but not DFO are protected against I/R injury. In addition, BPD but not DFO treatment in rat cardiomyoblast H9C2 cells significantly lowered chelatable mitochondrial iron and protected against H2O2 induced cell death. These results suggest that a reduction in baseline mitochondrial, but not cytosolic, iron is sufficient to protect against I/R injury. Conclusions: Our findings demonstrate that selective reduction in mitochondrial iron is protective in I/R injury. Thus, targeting mitochondrial iron with selective iron chelators may provide a novel approach for treatment of ischemic heart disease.

Difference in protective effects of three structurally similar flavonoid glycosides from Hypericum ascyron against H₂O₂-induced injury in H9c2 cardiomyoblasts.

According to previous studies, hyperoside possesses myocardial protective effects. To investigate whether isoquercitrin and isohyperoside have similar functions, the protective effects of isoquercitrin and isohyperoside against H2O2‑induced injury in H9c2 rat cardiomyoblasts were evaluated using a 3‑(4,5‑dimethylthiazol‑2‑yl)‑2,5‑diphenyltetrazolium bromide assay. The mechanism of action was investigated by assessing the leakage of lactate dehydrogenase (LDH) of hyperoside and isoquercitrin‑pretreated H9c2 cardiomyocytes following H2O2‑induced injury, and examining their effects on the levels of malondialdehyde (MDA) and superoxide dismutase (SOD) activity. The isolation of two flavonoid glycosides from H. ascyron was performed, following extraction, using semi‑preparative high performance liquid chromatography. Using the spectral characteristics, the structures of these compounds were identified as isoquercitrin and isohyperoside. This was the first time, to the best of our knowledge, that isohyperoside has been identified from H. ascyron. The results revealed that isoquercitrin and isohyperoside possessed similar protective effects to hyperoside against H2O2‑induced injury in H9c2 cells. The half maximal inhibitory concentration values of hyperoside, isoquercitrin and isohyperoside were 0.0008, 0.0017 and 0.0002 µM, respectively. Based on these results, isohyperoside possessed more marked protective effects against H2O2‑induced injury in the H9c2 cardiomyoblasts. The significant reduction in LDH leakage, decrease in MDA level and increase in SOD activity also provided evidence of the cardioprotective effects of isoquercitrin and isohyperoside. The present study reported for the first time, to the best of our knowledge, the myocardial protective effects of isoquercitrin and isohyperoside. The mechanism of action may involve protection of the cell membrane from oxidative damage.

Glutamine Reduces the Apoptosis of H9C2 Cells Treated with High-Glucose and Reperfusion through an Oxidation-Related Mechanism.

Mitochondrial overproduction of reactive oxygen species (ROS) in diabetic hearts during ischemia/reperfusion injury and the anti-oxidative role of glutamine have been demonstrated. However, in diabetes mellitus the role of glutamine in cardiomyocytes during ischemia/reperfusion injury has not been explored. To examine the effects of glutamine and potential mechanisms, in the present study, rat cardiomyoblast H9C2 cells were exposed to high glucose (33 mM) and hypoxia-reoxygenation. Cell viability, apoptosis, intracellular glutamine, and mitochondrial and intracellular glutathione were determined. Moreover, ROS formation, complex I activity, membrane potential and adenosine triphosphate (ATP) content were also investigated. The levels of S-glutathionylated complex I and mitochondrial apoptosis-related proteins, including cytochrome c and caspase-3, were analyzed by western blot. Data indicated that high glucose and hypoxia-reoxygenation were associated with a dramatic decline of intercellular glutamine and increase in apoptosis. Glutamine supplementation correlated with a reduction in apoptosis and increase of glutathione and glutathione reduced/oxidized ratio in both cytoplasm and mitochondria, but a reduction of intracellular ROS. Glutamine supplementation was also associated with less S-glutathionylation and increased the activity of complex I, leading to less mitochondrial ROS formation. Furthermore, glutamine supplementation prevented from mitochondrial dysfunction presented as mitochondrial membrane potential and ATP levels and attenuated cytochrome c release into the cytosol and caspase-3 activation. We conclude that apoptosis induced by high glucose and hypoxia-reoxygenation was reduced by glutamine supplementation, via decreased oxidative stress and inactivation of the intrinsic apoptotic pathway.