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Doxorubicin is the mainstay of treatment for various haematological malignancies and solid tumours. However, its clinical application may be hampered by dose-dependent cardiotoxicity. The mechanism of doxorubicin-induced cardiotoxicity may involve various signalling pathways including free radical generation, peroxynitrite formation, calcium overloading, mitochondrial dysfunction and alteration in apoptosis and autophagy. Interestingly, the use of resveratrol in combination with doxorubicin has been reported to prevent cardiac toxicity as well as to exert a synergistic effect against tumour cells both in vivo and in vitro. Thus, the aim of this review is to summarize current knowledge and to elucidate the protective effect of resveratrol in doxorubicin-induced cardiotoxicity., (© 2015 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

The aim of the present study was to investigate the mechanism underlying the rescue effect of lipid emulsion on bupivacaine (BPV)‑induced cardiomyocyte toxicity. The inhibitory effects of BPV on H9c2 myoblast cell proliferation were investigated using an MTT assay. The H9c2 myoblast cells were treated with either 1 mM BPV or 1% lipid emulsion (LE) alone, or co‑treated with both of the drugs. Cell apoptosis was detected using both Annexin V/propidium iodide staining and a terminal deoxynucleotidyl transferase dUTP assay. The protein expression levels of apoptosis-associated proteins were quantified using western blot analysis, and the mRNA expression levels were quantified by reverse transcription‑quantitative polymerase chain reaction. The expression levels of reactive oxidative species, malondialdehyde, superoxide dismutase, and catalase were quantified using the optical density values obtained from a spectrophotometer. In addition, the mechanism underlying the mitochondrial function of the H9c2 myoblast cells was investigated using both JC‑1 staining, and cyclosporin A and atractyloside treatment. The results indicated that the H9c2 myoblast cells treated with BPV exhibited significantly higher levels of apoptosis. Furthermore, BPV treatment increased the levels of oxidative stress, and caused mitochondrial dysfunction within the H9c2 myoblast cells. LE treatment reversed the effects of BPV treatment in the H9c2 myoblast cells.

Treatment with doxorubicin (DOX) is one of the major causes of chemotherapy-induced cardiotoxicity and is therefore, the principal limiting factor in the effectiveness of chemotherapy for cancer patients. DOX‑induced heart failure is thought to result from endoplasmic reticulum (ER) stress and cardiomyocyte apoptosis. Resveratrol (RV), a polyphenol antioxidant found in red wine, has been shown to play a cardioprotective role. The aim of the present study was to examine the effects of RV on DOX‑induced cardiotoxicity in H9c2 cells. We hypothesized that RV would protect H9c2 cells against DOX‑induced ER stress and subsequent cell death through the activation of the Sirt1 pathway. Our results demonstrated that the decrease observed in the viability of the H9c2 cells following exposure to DOX was accompanied by a significant increase in the expression of the ER stress‑related proteins, glucose‑regulated protein 78 (GRP78) and C/EBP homologous protein (CHOP). However, we found that RV downregulated the expression of ER stress marker protein in the presence of DOX and restored the viability of the H9c2 cells. Exposure to RV or DOX alone only slightly increased the protein expression of Sirt1, whereas a significant increase in Sirt1 protein levels was observed in the cells treated with both RV and DOX. The Sirt1 inhibitor, nicotinamide (NIC), partially neutralized the effects of RV on the expression of Sirt1 in the DOX‑treated cells and completely abolished the effects of RV on the expression of GRP78 and CHOP. The findings of our study suggest that RV protects H9c2 cells against DOX‑induced ER stress through ER stabilization, and more specifically through the activation of the Sirt1 pathway, thereby leading to cardiac cell survival.

Studying the importance of genetic factors in a desired cell type or tissue necessitates the use of precise genetic tools. With the introduction of bacteriophage Cre recombinase/loxP mediated DNA editing and promoter-specific Cre expression, it is feasible to generate conditional knockout mice in which particular genes are disrupted in a cell type-specific manner in vivo. In cardiac myocytes, this is often achieved through α-myosin heavy chain promoter (αMyHC)-driven Cre expression in conjunction with a loxP-site flanked gene of interest. Recent studies in other cell types demonstrate toxicity of Cre expression through induction of DNA damage. However, it is unclear to what extent the traditionally used αMyHC-Cre line [1] may exhibit cardiotoxicity. Further, the genotype of αMyHC-Cre(+/-) is not often included as a control group in cardiac myocyte-specific knockout studies. Here we present evidence that these αMyHC-Cre(+/-) mice show molecular signs of cardiac toxicity by 3months of age and exhibit decreased cardiac function by 6months of age compared to wild-type littermates. Hearts from αMyHC-Cre(+/-) mice also display evidence of fibrosis, inflammation, and DNA damage. Interestingly, some of the early functional changes observed in αMyHC-Cre(+/-) mice are sexually dimorphic. Given the high level of Cre recombinase expression resulting from expression from the αMyHC promoter, we asked if degenerate loxP-like sites naturally exist in the mouse genome and if so, whether they are affected by Cre in the absence of canonical loxP-sites. Using a novel bioinformatics search tool, we identified 619 loxP-like sites with 4 or less mismatches to the canonical loxP-site. 227 sites overlapped with annotated genes and 55 of these genes were expressed in cardiac muscle. Expression of ~26% of the 27 genes tested was disrupted in αMyHC-Cre(+/-) mice indicating potential targeting by Cre. Taken together, these results highlight both the importance of using αMyHC-Cre mice as controls in conditional knockout studies as well as the need for a less cardiotoxic Cre driver for the field., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

We have compared the cardiotoxicity of five platinum complexes in a model of isolated rat heart using the Langendorff technique. These effects were assessed via coronary flow (CF) and cardiac functional parameters. cis-Diamminedichloroplatinum(II) (cisplatin, CDDP), dichloro-(1,2-diaminocyclohexane)platinum(II) (Pt((II))DACHCl2), dichloro-(ethylenediamine)platinum(II) (Pt((II))ENCl2), tetrachloro-(1,2-diaminocyclohexane)platinum(IV) (Pt((IV))DACHCl4) and tetrachloro-(ethylenediamine)platinum(IV) (Pt((II))ENCl4) were perfused at increasing concentrations of 10(-8), 10(-7), 10(-6), 10(-5) and 10(-4) M during 30 min. In this paper, we report that cisplatin-induced dose-dependent effects on cardiac contractility and coronary flow both manifested as decrease in cardiac contractile force (dP/dt)max, heart rate and significant reduction in CF. Pt((II))ENCl2, Pt((IV))ENCl2 and Pt((IV))DACHCl4 did induce dose-dependent response only in case of CF. Our results could be also important for better understanding dose-dependent side effects of potential metal-based anticancer drugs.

Background: Variations in single nucleotide polymorphisms (SNPs) have been associated with enhanced drug efficacy and toxicity in cancer therapy. SNP variations in the ErbB2 gene have been identified that alter the protein sequence of the HER2-neu protein, but how these polymorphisms affect prognosis and response to HER2 targeted therapy is unknown. We examined eleven ErbB2 SNPs that alter the HER2-neu amino acid sequence to determine whether any of these particular polymorphisms were associated with increased trastuzumab cardiotoxicity in a case-control study., Methods: 140 subjects were enrolled from a single institution under Weill Cornell Medical College IRB protocol #0804009734. Patients were eligible if they had histologically or cytologically proven HER2-neu positive breast cancer and more than 3 months of trastuzumab therapy. Cases had either symptomatic CHF or a decline in LVEF of 15% (or if the LVEF <55%, a decline in LVEF of 10%) that resulted in at least temporary discontinuation of trastuzumab, whereas controls had no decline in their LVEF. Eleven ErbB2 single gene SNPs that resulted in an alteration in the HER2-neu protein amino acid sequence were studied. Single gene SNP analysis was carried out using SNP genotyping assays from genomic DNA obtained from peripheral blood or buccal swab., Results: Only two of the ErbB2 SNPs (Ile 655 Val and Pro 1170 Ala) were found to have variation. There was no association between codon 665 and cardiotoxicity; however the proline variant of amino acid 1170 was more likely than the alanine variant to be found in cases with trastuzumab cardiotoxicity (35% of case patients as compared to 17% of controls, p = 0.04). This association remained significant in multivariable analysis taking into account age, race, and history of hypertension (adjusted OR = 2.60, 95% CI = 1.02, 6.62, p = 0.046)., Conclusions: The Her2/neu Pro 1170 Ala polymorphism can be used to identify a subset of patients who are at increased risk of cardiotoxicity from trastuzumab therapy. Her2/neu single nucleotide polymorphisms may be useful in conjunction with other biomarkers to risk stratify patients in order to optimize clinical management.

Cardiovascular (CV) toxicity is a leading cause of drug attrition and withdrawal. Introducing in vitro assays with higher throughput should permit earlier CV hazard identification and enable medicinal chemists to design-out liabilities. Heretofore, development of in vitro CV assays has been limited by the challenge of replicating integrated cardiovascular physiology while achieving the throughput and consistency required for screening. These challenges appear to be met with a combination of human stem cell-derived cardiomyocytes (CM) which beat spontaneously and monitoring the response with technology that can assess drug-induced changes in voltage dependent contraction such as cellular impedance which has been validated with excellent predictivity for drug-induced arrhythmia and contractility. Here, we review advances in cardiomyocyte impedance with emphasis on stem cell-derived cardiomyocyte models for toxicity screening. Key perspectives include: the electrical principles of impedance technology, impedance detection of cardiomyocyte beating, beat parameter selection/analysis, validation in toxicity and drug discovery, and future directions. As a conclusion, an in vitro screening cascade is proffered using the downstream, inclusive detection of CM impedance assays as a primary screen followed by complementary CM assays chosen to enable mechanism-appropriate follow-up. The combined approach will enhance testing for CV liabilities prior to traditional in vivo models.

Reactive oxygen species (ROS) such as O2(-), hydrogen peroxide, and OH(-) are highly toxic to cells. Cellular antioxidant enzymes and free radical scavengers normally protect a cell from toxic effects of ROS. However, when generation of ROS overtakes the antioxidant defense of the cells, it leads to various pathological conditions. The present study investigated the protective efficacy of α-tocopherol on the peroxidative damage and abnormal antioxidant levels in the myocardial tissue of camptothecin (CPT), administered at the dosage of 6 mg/kg/day in male Wistar rats. CPT-administered rats showed significant increase (p < 0.001) in lipid peroxidation and abnormal changes in the activities/levels of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione S-transferase) and nonenzymic antioxidants (reduced glutathione and vitamin E). Alterations in the levels of tissue alkaline phosphatase, lactate dehydrogenase (p < 0.01), alanine transaminase (p < 0.001), and aspartate transaminase (p < 0.001) were also observed in CPT-treated rats. In contrast, rats pretreated with α-tocopherol showed significant revision of elevated levels of lipid peroxides and abnormal antioxidant enzyme activity suggesting the ameliorative property of vitamin E. Histopathological alterations in the heart tissue observed after CPT administration were also protected in animals that were pretreated with vitamin E. Based on our results, we conclude that supplementation of vitamin E may improve the efficacy of standard and experimental cancer therapies by subsiding the toxic effect of the antineoplastic agent., (© The Author(s) 2014.)

Some dietary supplements may contain cardiac stimulants and potential cardiotoxins. In vitro studies may identify ingredients of concern. A beating human cardiomyocyte cell line was used to evaluate cellular effects following phenylethylamine (PEA), higenamine, ephedrine or caffeine treatment. PEA and higenamine exposure levels simulated published blood levels in humans or animals after intravenous administration. Ephedrine and caffeine levels approximated published blood levels following human oral intake. At low or midrange levels, each chemical was examined plus or minus 50 µM caffeine, simulating human blood levels reported after consumption of caffeine-enriched dietary supplements. To measure beats per minute (BPM), peak width, etc., rhythmic rise and fall in intracellular calcium levels following 30 min of treatment was examined. Higenamine 31.3 ng/ml or 313 ng/ml significantly increased BPM in an escalating manner. PEA increased BPM at 0.8 and 8 µg/ml, while 80 µg/ml PEA reduced BPM and widened peaks. Ephedrine produced a significant BPM dose response from 0.5 to 5.0 µM. Caffeine increased BPM only at a toxic level of 250 µM. Adding caffeine to PEA or higenamine but not ephedrine further increased BPM. These in vitro results suggest that additional testing may be warranted in vivo to further evaluate these effects., (Published by Elsevier Ltd.)

Age is a known susceptibility factor for the cardiotoxicity of several anticancer drugs, including mitoxantrone (MTX). The impact of anticancer drugs in young patients is underestimated, thus we aimed to evaluate the cardiotoxicity of MTX in juvenile and adult animals. Juvenile (3 week-old) and adult (8-10 week-old) male CD-1 mice were used. Each group was treated with a 9.0mg/kg cumulative dose of MTX or saline; they were maintained in a drug-free period for 3-weeks after the last administration to allow the development of late toxicity (protocol 1), or sacrificed 24h after the last MTX administration to evaluate early cardiotoxicity (protocol 2). In protocol 1, no adult mice survived, while 2 of the juveniles reached the end of the protocol. High plasma aspartate aminotransferase/alanine aminotransferase ratio and a high cardiac reduced/oxidized glutathione ratio were found in the surviving MTX-treated juvenile mice. In protocol 2, a significant decrease in plasma creatine-kinase MB in juveniles was found 24h after the last MTX-administration. Cardiac histology showed that both MTX-treated populations had significant damage, although higher in adults. However, MTX-treated juveniles had a significant increase in fibrotic tissue. The MTX-treated adults had higher values of cardiac GSSG and protein carbonylation, but lower cardiac noradrenaline levels. For the first time, mature adult animals were shown to be more susceptible to MTX as evidenced by several biomarkers, while young animals appear to better adjust to the MTX-induced cardiac injury. Even so, the higher level of fibrotic tissue and the histological damage showed that MTX also causes cardiac damage in the juvenile population., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

The cardiac toxicity of zebrafish embryos in response to the lethal dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been well characterized. Dioxin contamination levels in nature are usually lower, however, and sublethal TCDD toxicity is less investigated. The present study found that the nonlethal doses of TCDD for 72-h-postfertilization (hpf) zebrafish embryos were 25 pg/mL and lower. For the present study, sublethal TCDD concentrations of 10 pg/mL and 25 pg/mL were selected, and their toxicity was then characterized. The results showed that embryos still exhibited acute and subchronic cardiac toxicity at these 2 dosages. The stroke volume and cardiac output of these embryos significantly declined early until 8 d postexposure. Embryos' heart size became smaller, and the hearts contained fewer cardiomyocytes per heart, with decreased cardiomyocyte proliferation. Apoptosis was not detected either in the TCDD-treated or the control hearts. Real-time polymerase chain reaction (PCR) revealed that the transcription of a battery of cell-cycle-related genes was suppressed within the sublethal TCDD-treated heart. In contrast, embryonic jaw development seemed not to be affected. The present study suggests that dioxin contamination, even at lower levels, might lead to cardiac toxicity in fish embryos. Such cardiac toxicity presents as disrupted normal heart function, originating from the anti-proliferative effect of sublethal TCDD on cardiomyocytes., (© 2014 SETAC.)

The incidence of drug-induced structural cardiotoxicity, which may lead to heart failure, has been recognized in association with the use of anthracycline anti-cancer drugs for many years, but has also been shown to occur following treatment with the new generation of targeted anti-cancer agents that inhibit one or more receptor or non-receptor tyrosine kinases, serine/threonine kinases as well as several classes of non-oncology agents. A workshop organized by the Medical Research Council Centre for Drug Safety Science (University of Liverpool) on 5 September 2013 and attended by industry, academia and regulatory representatives, was designed to gain a better understanding of the gaps in the field of structural cardiotoxicity that can be addressed through collaborative efforts. Specific recommendations from the workshop for future collaborative activities included: greater efforts to identify predictive (i) preclinical; and (ii) clinical biomarkers of early cardiovascular injury; (iii) improved understanding of comparative physiology/pathophysiology and the clinical predictivity of current preclinical in vivo models; (iv) the identification and use of a set of cardiotoxic reference compounds for comparative profiling in improved animal and human cellular models; (v) more sharing of data (through publication/consortia arrangements) on target-related toxicities; (vi) strategies to develop cardio-protective agents; and (vii) closer interactions between preclinical scientists and clinicians to help ensure best translational efforts., (© 2014 The British Pharmacological Society.)

Cardiotoxicity is one of the major safety concerns in drug development. Therefore, detecting and monitoring cardiotoxicity throughout preclinical and clinical studies is important for pharmaceutical companies. The present study was conducted in order to explore a plasma miRNA biomarker for cardiotoxicity in rats. As organ specificity is an important factor for a biomarker, we analyzed the miRNA microarray dataset in 55 organs/tissues in normal male rats. Based on this analysis, 5 miRNAs consisting of miR-208 (heart-specific), miR-1, miR-133a, miR-133b (heart and skeletal muscle-specific) and miR-206 (skeletal muscle-specific) were selected. Next, we evaluated the usefulness of those 5 miRNAs as circulating biomarkers in rats administered with single-dose isoproterenol or doxorubicin. Plasma miR-208 was consistently increased through 24 h after dosing in rats administered with isoproterenol, whereas plasma concentrations of cardiac troponin (cTn) showed transient elevation. In contrast, the plasma levels of miR-1, miR-133a, miR-133a and miR-206 were elevated after treatment with doxorubicin, probably as a result of skeletal muscle toxicity. Additionally, the plasma miR-208 level was elevated even after repeat-dose administration (once daily for 7 days) of isoproterenol under which the pathological condition proceeded to the sub-chronic phase such as fibrosis. Thus, our data suggest that miR-208 is a promising plasma biomarker for cardiotoxicity in rats. Monitoring of plasma miR-208 levels in rats may lead to more accurate evaluation of cardiotoxicity in preclinical studies., (Copyright © 2014 John Wiley & Sons, Ltd.)

The present study was undertaken to evaluate the cardioprotective role of (-)-epigallocatechin-gallate (EGCG) against Fluoride (F) induced oxidative stress mediated cardiotoxicity in rats. The animals exposed to F as sodium Fluoride (NaF) (25mg/kg BW) for 4 weeks exhibited a significant increase in the levels of cardiac troponins T and I (cTnT & I), cardiac serum markers, lipid peroxidative markers and plasma total cholesterol (TC), triglycerides (TG), phospholipids (PL), free fatty acids (FFA), low density lipoprotein cholesterol, very low density lipoprotein cholesterol as well as cardiac lipids profile (TC, TG and FFA) with the significant decrease of high density lipoprotein cholesterol and cardiac phospholipids. F intoxication also decreased the levels of mitochondrial enzymes such as ICDH, SDH, MDH, α-KGDH and NADH in the cardiac tissue of rats. The mitochondrial Ca(2+) ion level was also significantly reduced along with the significant decrease in the levels of enzymatic and non enzymatic antioxidants. Furthermore, F treatment significantly increased the DNA fragmentation, up regulate cardiac pro-apoptotic markers, inflammatory markers and down-regulate the anti-apoptotic markers in the cardiac tissue. Pre administration of EGCG (40mg/kg/bw) in F intoxicated rats remarkably recovered all these altered parameters to near normalcy through its antioxidant nature. Thus, results of the present study clearly demonstrated that treatment with EGCG prior to F intoxication has a significant role in protecting F-induced cardiotoxicity and dyslipidemia in rats., (Copyright © 2014 Elsevier GmbH. All rights reserved.)

Aim: To identify gene variants responsible for anthracycline-induced cardiotoxicity., Patients & Methods: Polymorphisms of the NADPH oxidase subunits and of the anthracycline transporters ABCC1, ABCC2 and SLC28A3 were genotyped in elderly patients (61-80 years) treated for aggressive CD20(+) B-cell lymphomas with CHOP-14 with or without rituximab and followed up for 3 years., Results: The accumulation of RAC2 subunit genotypes TA/AA among cases was statistically significant upon adjustment for gender, age and doxorubicin dose in a multivariate logistic regression analysis (OR: 2.3, p = 0.028; univariate: OR: 1.8, p = 0.077). RAC2 and CYBA genotypes were significantly associated with anthracycline-induced cardiotoxicity in a meta-analysis of this and a similar previous study., Conclusion: Our results support the theory that NADPH oxidase is involved in anthracycline-induced cardiotoxicity. Original submitted 9 July 2014; Revision submitted 19 December 2014.

Doxorubicin (DOX) is an effective chemotherapeutic drug used for the treatment of a variety of malignancies. Unfortunately, time and dose-dependent DOX therapy induces cardiotoxicity and heart failure. We previously reported that transplanted embryonic stem (ES) cells and the conditioned medium (CM) can repair and regenerate injured myocardium in acute DOX-induced cardiomyopathy (DIC). However, the effectiveness of ES cell and CM therapeutics has not been challenged in the chronic DIC model. To this end, the long-term impact of ES cells and CM on apoptosis, fibrosis, cytoplasmic vacuolization, oxidative stress, and their associated mediators were examined. Four weeks post-DIC, ES cells and CM-transplanted hearts showed a significant decrease in cardiac apoptotic nuclei, which was consequent to modulation of signaling molecules in the Akt pathway including PTEN, Akt, and mTOR. Cytoplasmic vacuolization was reduced following treatment with ES cells and CM, as was cardiac fibrosis, which was attributable to downregulation of MMP-9 activity. Oxidative stress, as evidenced by DHE staining and lipid peroxide concentration, was significantly diminished, and preservation of the antioxidant defense system was observed following CM and ES cell transplantation. In conclusion, our data suggest that transplanted ES cells and CM have long-term potentiation to significantly mitigate various adverse pathological mechanisms present in the injured chronic DIC heart.

The anticancer efficacy of anthracyclines is limited by cumulative dose-dependent early and delayed cardiotoxicity resulting in congestive heart failure. Mechanisms responsible for anthracycline-induced heart damage are controversially discussed and effective preventive measures are preferable. Here, we analyzed the influence of the lipid lowering drug lovastatin on anthracycline-induced late cardiotoxicity three month after treatment of C57BL/6 mice with five low doses of doxorubicin (5×3mg/kg BW; i.p.). Doxorubicin increased the cardiac mRNA levels of BNP, IL-6 and CTGF, while the expression of ANP remained unchanged. Lovastatin counteracted these persisting cardiac stress responses evoked by the anthracycline. Doxorubicin-induced fibrotic alterations were neither detected by histochemical collagen staining of heart sections nor by analysis of the mRNA expression of collagens. Extensive qRT-PCR-array based analyses revealed a large increase in the mRNA level of heat shock protein Hspa1b in doxorubicin-treated mice, which was mitigated by lovastatin co-treatment. Electron microscopy together with qPCR-based analysis of mitochondrial DNA content indicate that lovastatin attenuates doxorubicin-stimulated hyperproliferation of mitochondria. This was not paralleled by increased expression of oxidative stress responsive genes or senescence-associated proteins. Echocardiographic analyses disclosed that lovastatin protects from the doxorubicin-induced decrease in the left ventricular posterior wall diameter (LVPWD), while constrictions in fractional shortening (FS) and ejection fraction (EF) evoked by doxorubicin were not amended by the statin. Taken together, the data suggest beneficial effects of lovastatin against doxorubicin-induced delayed cardiotoxicity. Clinical studies are preferable to scrutinize the usefulness of statins for the prevention of anthracycline-induced late cardiotoxicity., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Tilmicosin (TIL) is a long-acting macrolide antibiotic approved for the treatment of cattle with Bovine Respiratory Disease. However, overdose of TIL has been reported to induce cardiotoxicity. The purpose of our experiment was to evaluate the protective effects of Commiphora molmol (mirazid (MRZ); myrrh) and (or) ascorbic acid (AA) against TIL-induced cardiotoxicity in mice. MRZ and AA were orally administered using stomach gavage, either alone or in combination for 5 consecutive days, followed with a single TIL overdose. TIL overdose induced a significant increase in serum levels of cardiac damage biomarkers (AST, LDH, CK, CK-MB, and cTnT), as well as cardiac lipid peroxidation, but cardiac levels of antioxidant biomarkers (GSH, SOD, CAT, and TAC) were decreased. Both MRZ and AA tended to normalize the elevated serum levels of cardiac injury biomarkers. Furthermore, MRZ and AA reduced TIL-induced lipid peroxidation and oxidative stress parameters. MRZ and AA combined produced a synergistic cardioprotective effect. We conclude that myrrh and (or) vitamin C administration minimizes the toxic effects of TIL through their free-radical-scavenging and potent antioxidant activities.

Introduction: Mitragynine is a major bioactive compound of Kratom, which is derived from the leave extracts of Mitragyna speciosa Korth or Mitragyna speciosa (M. speciosa), a medicinal plant from South East Asia used legally in many countries as stimulant with opioid-like effects for the treatment of chronic pain and opioid-withdrawal symptoms. Fatal incidents with Mitragynine have been associated with cardiac arrest. In this study, we determined the cardiotoxicity of Mitragynine and other chemical constituents isolated using human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs)., Methods and Results: The rapid delayed rectifier potassium current (IKr), L-type Ca2+ current (ICa,L) and action potential duration (APD) were measured by whole cell patch-clamp. The expression of KCNH2 and cytotoxicity was determined by real-time PCR and Caspase activity measurements. After significant IKr suppression by Mitragynine (10 µM) was confirmed in hERG-HEK cells, we systematically examined the effects of Mitragynine and other chemical constituents in hiPSC-CMs. Mitragynine, Paynantheine, Speciogynine and Speciociliatine, dosage-dependently (0.1∼100 µM) suppressed IKr in hiPSC-CMs by 67%∼84% with IC50 ranged from 0.91 to 2.47 µM. Moreover, Mitragynine (10 µM) significantly prolonged APD at 50 and 90% repolarization (APD50 and APD90) (439.0±11.6 vs. 585.2±45.5 ms and 536.0±22.6 vs. 705.9±46.1 ms, respectively) and induced arrhythmia, without altering the L-type Ca2+ current. Neither the expression, and intracellular distribution of KCNH2/Kv11.1, nor the Caspase 3 activity were significantly affected by Mitragynine., Conclusions: Our study indicates that Mitragynine and its analogues may potentiate Torsade de Pointes through inhibition of IKr in human cardiomyocytes.

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents in the treatment of a variety of tumors. However, its clinical use has been compromised by the risk of cardiotoxicity. Thus, many efforts have been focused on exploring new strategies to prevent or reverse DOX-induced cardiotoxicity. Recently, deep sea water (DSW) has drawn much scientific interest for therapeutic intervention due to its enrichment in nutrients and minerals. In this study, we investigated whether DSW has protective effects against DOX-induced cardiotoxicity. Pre-treatment with DSW significantly increased the viability of DOX-treated rat H9c2 cardiac muscle cells. This protective effect of DSW appears to be mediated through the inhibition of DNA damage rather than suppression of reactive oxygen species (ROS) production in DOX‑treated H9c2 cardiac muscle cells. The inhibitory effect of DSW on DOX-induced DNA damage subsequently attenuated apoptotic signaling such as activation of cysteine-aspartic acid protease-3 (caspase-3) and fragmentation of poly(ADP-ribose) polymerase (PARP), whereas the expression of anti-apoptotic protein B-cell lymphoma-extra large (Bcl-xL) was increased. Moreover, DSW treatment rescued the activation of protein kinase B (Akt) to protect cells from DOX-triggered apoptosis. Taken together, our data showed that DSW has protective effects against DOX-induced cardiotoxicity, suggesting that DSW has some promise as a novel protective supplement for promoting the successful use of DOX in clinical regimen.

Background and Purpose: Doxorubicin-based chemotherapy induces cardiotoxicity, which limits its clinical application. We previously reported the protective effects of quercetin against doxorubicin-induced hepatotoxicity. In this study, we tested the effects of quercetin on the expression of Bmi-1, a protein regulating mitochondrial function and ROS generation, as a mechanism underlying quercetin-mediated protection against doxorubicin-induced cardiotoxicity., Experimental Approach: Effects of quercetin on doxorubicin-induced cardiotoxicity was evaluated using H9c2 cardiomyocytes and C57BL/6 mice. Changes in apoptosis, mitochondrial function, oxidative stress and related signalling were evaluated in H9c2 cells. Cardiac function, serum enzyme activity and reactive oxygen species (ROS) generation were measured in mice after a single injection of doxorubicin with or without quercetin pre-treatment., Key Results: In H9c2 cells, quercetin reduced doxorubicin-induced apoptosis, mitochondrial dysfunction, ROS generation and DNA double-strand breaks. The quercetin-mediated protection against doxorubicin toxicity was characterized by decreased expression of Bid, p53 and oxidase (p47 and Nox1) and by increased expression of Bcl-2 and Bmi-1. Bmi-1 siRNA abolished the protective effect of quercetin against doxorubicin-induced toxicity in H9c2 cells. Furthermore, quercetin protected mice from doxorubicin-induced cardiac dysfunction that was accompanied by reduced ROS levels and lipid peroxidation, but enhanced the expression of Bmi-1 and anti-oxidative superoxide dismutase., Conclusions and Implications: Our results demonstrate that quercetin decreased doxorubicin-induced cardiotoxicity in vitro and in vivo by reducing oxidative stress by up-regulation of Bmi-1 expression. The findings presented in this study have potential applications in preventing doxorubicin-induced cardiomyopathy., (© 2014 The British Pharmacological Society.)

This study investigated whether cyclophosphamide (CP) and ifosfamide (IFO) therapy alters the expression of the key genes engaged in long-chain fatty acid (LCFA) oxidation outside rat heart mitochondria, and if so, whether these alterations should be viewed as a mechanism during CP- and IFO-induced cardiotoxicity. Adult male Wistar albino rats were assigned to one of the six treatment groups: Rats in group 1 (control) and group 2 (L-carnitine) were injected intraperitoneal (i.p.) with normal saline and L-carnitine (200 mg/kg/day), respectively, for 10 successive days. Animals in group 3 (CP group) were injected i.p. with normal saline for 5 days before and 5 days after a single dose of CP (200 mg/kg, i.p.). Rats in group 4 (IFO group) received normal saline for 5 successive days followed by IFO (50 mg/kg/day, i.p.) for 5 successive days. Rats in group 5 (CP-carnitine supplemented) were given the same doses of L-carnitine as group 2 for 5 days before and 5 days after a single dose of CP as group 3. Rats in group 6 (IFO-carnitine supplemented) were given the same doses of L-carnitine as group 2 for 5 days before and 5 days concomitant with IFO as group 4. Immediately, after the last dose of the treatment protocol, blood samples were withdrawn and animals were killed for biochemical, histopathological and gene expression studies. Treatment with CP and IFO significantly decreased expression of heart fatty acid binding protein (H-FABP) and carnitine palmitoyltransferase I (CPT I) genes in cardiac tissues. Moreover, CP but not IFO significantly increased acetyl-CoA carboxylase2 mRNA expression. Conversely, IFO but not CP significantly decreased mRNA expression of malonyl-CoA decarboxylase. Both CP and IFO significantly increased serum lactate dehydrogenase, creatine kinase isoenzyme MB and malonyl-CoA content and histopathological lesions in cardiac tissues. Interestingly, carnitine supplementation completely reversed all the biochemical, histopathological and gene expression changes induced by CP and IFO to the control values, except CPT I mRNA, and protein expression remained inhibited by IFO. Data from the current study suggest, for the first time, that (1) CP and IFO therapy is associated with the inhibition of the expression of H-FABP and CPT I genes in cardiac tissues with the consequent inhibition of mitochondrial transport and oxidation of LCFA. (2) The progressive increase in cardiotoxicity enzymatic indices and the decrease in H-FABP and CPT I expression may point to the possible contribution of these genes to CP- and IFO-induced cardiotoxicity.

Interventions to reduce the cardiotoxicity of doxorubicin are clinically relevant. Pharmacological preconditioning mimicking ischemic preconditioning has been demonstrated with morphine and represents an acceptable clinical intervention. The purpose of this study was to examine if pretreatment in vivo with morphine could reduce doxorubicin-induced cardiotoxicity ex vivo in a rat model. Wistar rats were divided into six groups and pretreated with an intraperitoneal (i.p.) injection of 3 or 10 mg/kg morphine, 1 mg/kg naloxone and saline, 1 mg/kg naloxone and 3 mg/kg morphine or saline, 60 min before excision of the heart. Biochemical indices such as troponin T (TnT) and hydrogen peroxide (H2O2) in effluate were measured together with physiological parameters in Langendorff hearts before and after doxorubicin infusion (2 mg/mL 0.05 mL/min for 45 min). Myocardial content of doxorubicin was measured at the end of infusion. Pretreatment with morphine, irrespective of dosage, produced a significant loss in left ventricular-developed pressure and an increase of TnT and H2O2 in effluate before doxorubicin infusion (p < 0.05). Morphine also produced a significant increase in left ventricular end-diastolic pressure and an increase of TnT and H2O2 in effluate (p < 0.05) at the end of doxorubicin infusion. Naloxone, a non-selective opioid receptor antagonist, abolished the effects of morphine both before and after doxorubicin infusion. Morphine, irrespective of dosage, increased myocardial content of doxorubicin compared to pretreatment with saline (p < 0.05). Pretreatment with morphine is associated with a cardiodepressive effect and enhances cardiotoxicity of doxorubicin measured by increased myocardial accumulation of doxorubicin and physiological and biochemical indices. The negative effects observed in our rat model are abolished by naloxone.

The possible effectiveness of resveratrol, a polyphenol present in different plants comprising berries, grapes and peanuts, on the prevention of doxorubicin-induced cardiac toxicity and fibrosis was investigated. Forty adult male Wistar albino rats were divided into four groups. Group I received normal saline, group II gavaged with resveratrol (20 mg/kg, daily for 4 weeks), group III received doxorubicin (2.5 mg/kg i.p. in six injections for 2 weeks; accumulative dose of 15 mg/kg), and group IV received doxorubicin + resveratrol (starting resveratrol intake 2 weeks before doxorubicin administration). Resveratrol significantly alleviated the increase in left ventricular lipid peroxidation, hydroxyproline, and tumor necrosis factor alpha levels as well as serum creatine kinase-myocardial band (CK-MB) activity and prevented the decrease in body and heart weights in doxorubicin-treated group. However, a marked protection against reduced glutathione content depletion and superoxide dismutase activity reduction was observed in the left ventricles of rats pretreated with resveratrol in combination with doxorubicin. Resveratrol also ameliorated the up-regulation of left ventricular caspase-3 and transforming growth factor-beta1 gene expression as well as left ventricular histopathological changes including necrosis and fibrosis induced by doxorubicin. Collectively, our results suggest that resveratrol provides a significant protection against doxorubicin-induced cardiotoxicity and fibrosis in rats. Therefore, it may be used as a promising cardioprotective agent in patients treated with doxorubicin due to malignant diseases. So, further clinical trials are required to confirm these findings.

Lipid peroxidation (LP), induced by oxidative stress, is associated with degenerative processes. 4-Hydroxy-2-nonenal (HNE), a highly reactive diffusible product of LP, is considered by-product and mediator of oxidative stress. Its level increases under pathological conditions such as cardiovascular diseases. In this study, we partially characterized the mechanisms of HNE-mediated cytotoxicity in cardiomyocytes. After establishing that pathophysiological doses of HNE trigger cell death dependent on the incubation time and dose of HNE (LD50 = 4.4 μM), we tackled the mechanisms that underlie the cell death induced by HNE. Our results indicate that HNE rapidly increases intracellular Ca(2+); it also increases the rate of reactive oxygen species generation and causes a loss of mitochondrial membrane potential (ΔΨm) as well as a decrease in the ATP and GSH levels. Such alterations result in the activation of caspase-3 and DNA breakdown, both characteristic features of apoptotic cell death, as well as disruption of the cytoskeleton. Moreover, the nucleophilic compounds N-acetyl-cysteine and β-mercapto-propionyl-glycine, and the synthetic antioxidant Trolox exert a potent antioxidant action against HNE damage; this suggests its use as effective compounds in order to reduce the damage occurred as consequence of cardiovascular disorders in which oxidative stress and hence LP take place.

Catecholamines are endogenous amines that participate in the maintenance of cardiovascular system homeostasis. However, excessive release or exogenous administration of catecholamines is cardiotoxic. The synthetic catecholamine, isoprenaline (isoproterenol, ISO), with non-selective β-agonistic activity has been used as a viable model of acute myocardial toxicity for many years. Since the pathophysiology of ISO-cardiotoxicity is complex, the aim of this study was to elucidate the effect of oral quercetin pretreatment on myocardial ISO toxicity. Wistar-Han rats were randomly divided into four groups: solvent or quercetin administered orally by gavage in a dose of 10 mg kg(-1) daily for 7 days were followed by s.c. water for injection or ISO in a dose of 100 mg kg(-1). Haemodynamic, ECG and biochemical parameters were measured; effects on blood vessels and myocardial histology were assessed, and accompanying pharmacokinetic analysis was performed. Quercetin was unable to protect the cardiovascular system against acute ISO cardiotoxicity (stroke volume decrease, cardiac troponin T release, QRS-T junction elevation and histological impairment). The sole positive effect of quercetin on catecholamine-induced cardiotoxicity was the normalization of increased left ventricular end-diastolic pressure caused by ISO. Quercetin did not reverse the increased responsiveness of rat aorta to vasoconstriction in ISO-treated animals, but it decreased the same parameter in the control animals. Accompanying pharmacokinetic analysis showed absorption of quercetin and its metabolite 3-hydroxyphenylacetic acid formed by bacterial microflora. In conclusion, a daily oral dose of 10 mg kg(-1) of quercetin for 7 days did not ameliorate acute ISO-cardiovascular toxicity in rats despite minor positive cardiovascular effects.

Hydrogen sulfide (H₂S) protects cardiomyoblasts against high glucose (HG)-induced injury by inhibiting the activation of p38 mitogen-activated protein kinase (MAPK). This study aims to determine whether the leptin-p38 MAPK pathway is involved in HG-induced injury and whether exogenous H2S prevents the HG-induced insult through inhibition of the leptin-p38 MAPK pathway in H9c2 cells. H9c2 cells were treated with 35 mM glucose (HG) for 24 h to establish a HG-induced cardiomyocyte injury model. Cell viability; mitochondrial membrane potential (ΔΨ m); apoptosis; reactive oxygen species (ROS) level; and leptin, leptin receptor, and p38 MAPK expression level were measured by the methods indicated. The results showed pretreatment of H9c2 cells with NaHS before exposure to HG led to an increase in cell viability, decrease in apoptotic cells, ROS generation, and a loss of ΔΨ m. Exposure of H9c2 cells to 35 mM glucose for 24 h significantly upregulated the expression levels of leptin and leptin receptors. The increased expression levels of leptin and leptin receptors were markedly attenuated by pretreatment with 400 μM NaHS. In addition, the HG-induced increase in phosphorylated (p) p38 MAPK expression was ameliorated by pretreatment with 50 ng/ml leptin antagonist. In conclusion, the present study has demonstrated for the first time that the leptin-p38 MAPK pathway contributes to the HG-induced injury in H9c2 cells and that exogenous H₂S protects H9c2 cells against HG-induced injury at least in part by inhibiting the activation of leptin-p38 MAPK pathway.

Background: Treatment with daunorubicin (DNR) in acute myeloid leukemia is moderately effective and associated with significant side effects, including cardiac toxicity. We recently developed a nanomicellar formulation of DNR that specifically targets acute myeloid leukemia stem cells., Materials & Methods: Pharmacokinetics analysis of free DNR, DNR in nanomicellar formulations was performed in Balb/c mice and Sprague-Dawley rats. Histochemical staining, caspase 3/7, troponin and creatine kinase MB isoenzyme were used to assess toxicity., Results: Compared with free DNR, the nanomicellar formulations of DNR had less cardiotoxicity as evidenced by milder histopathological changes, lower caspase 3/7 activity in heart tissue (p = 0.002), lower plasma creatine kinase MB isoenzyme (p = 0.002) and troponin concentrations (p = 0.001) postinjection. The area under curve concentration of DNR in micelles increased by 31.9-fold in mice (p < 0.0001) and 22.0-fold higher in rats (p < 0.001)., Conclusion: Leukemia stem cell-targeting micelles dramatically change the pharmacokinetics and reduce the cardiac toxicity of DNR, which may enable improved DNR-based treatment of acute myeloid leukemia.

Cardiotoxicity is an important side effect of cytotoxic drugs and may be a risk factor of long-term morbidity for both patients during therapy and also for staff exposed during the phases of manipulation of antiblastic drugs. The mechanism of cardiotoxicity studied in vitro and in vivo essentially concerns the formation of free radicals leading to oxidative stress, with apoptosis of cardiac cells or immunologic reactions, but other mechanisms may play a role in antiblastic-induced cardiotoxicity. Actually, some new cytotoxic drugs like trastuzumab and cyclopentenyl cytosine show cardiotoxic effects. In this report we discuss the different mechanisms of cardiotoxicity induced by antiblastic drugs assessed using animal models.

Objective: This study aimed to investigate the acute cardiotoxic effects of high dose toluene and its damage mechanisms on heart tissue in the acute period., Methods: Twenty adult male Wistar Albino rats (200-220 g) were used in this controlled experimental animal study. Animals were divided into two equal groups: a control group (Group 1) and a high dose (6 mL/kg/gavage) toluene-administered group (Group 2). Arterial blood pressure (BP) and heart rate (HR) values were measured at 30th, 60th and 90th minutes after toluene was administered. At the end of the experimental period, blood samples and heart tissues were taken from the rats. Serum troponin T levels were assayed. Heart tissue sections were stained using routine histological methods and examined under a light microscope. In addition, the sections were immunohistochemically stained using the avidin-biotin-peroxidase method to determine caspase-3 immunoreactivity and TUNEL to detect apoptosis. To compare the apoptotic index, the Mann-Whitney U test was used. For comparisons between the two groups, the independent t- test was used. In addition, time-based changes of intra-group parameters were evaluated using paired t tests., Results: BP and HR values were low in toluene-treated rats compared to the control group. Troponin T levels were increased in toluene-administered animals as compared with controls [Toluene group: 0.140 (0.010-2.000) ng/mL vs control group: 0.010 (0.010-0.010) ng/mL, p=0.01]. Histopathologic examination of heart tissue sections showed congestion and edema in toluene administrated rats. Higher TUNEL positivity and (+++) immunoreactivity for caspase-3 protein were observed in the toluene group compared to the control group., Conclusion: The present study demonstrated that high doses of toluene cause apoptosis and may lead to impairment of cardiac function in the acute period.