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Background/Aims: Melatonin possesses many biological activities such as antioxidant and anti-aging. Cardiac progenitor cells (CPCs) have emerged as a promising therapeutic strategy for myocardial infarction (MI). However, the low survival of transplanted CPCs in infarcted myocardium limits the successful use in treating MI. In the present study, we aimed to investigate if melatonin protects against oxidative stress-induced CPCs damage and enhances its therapeutic efficacy for MI. Methods: TUNEL assay and EdU assay were used to detect the effects of melatonin and miR-98 on H2O2-induced apoptosis and proliferation. MI model was used to evaluate the potential cardioprotective effects of melatonin and miR-98. Results: Melatonin attenuated H2O2-induced the proliferation reduction and apoptosis of c-kit+ CPCs in vitro, and CPCs which pretreated with melatonin significantly improved the functions of post-infarct hearts compared with CPCs alone in vivo. Melatonin was capable to inhibit the increase of miR-98 level by H2O2 in CPCs. The proliferation reduction and apoptosis of CPCs induced by H2O2 was aggravated by miR-98. In vivo, transplantation of CPCs with miR-98 silencing caused the more significant improvement of cardiac functions in MI than CPCs. MiR-98 targets at the signal transducer and activator of the transcription 3 (STAT3), and thus aggravated H2O2-induced the reduction of Bcl-2 protein. Conclusions: Pre-treatment with melatonin protects c-kit+ CPCs against oxidative stress-induced damage via downregulation of miR-98 and thereby increasing STAT3, representing a potentially new strategy to improve CPC-based therapy for MI. [ABSTRACT FROM AUTHOR]

Background/Aims: Deregulated myocardial fibrosis is associated with a wide spectrum of cardiac conditions, being considered one of the major causes for heart disease. Our study was designed to investigate the role of microRNA-328 (miR-328) in regulating cardiac fibrosis. Methods: We induced cardiac fibrosis following MI by occlusion of the left coronary artery in C57BL/6 mice. Real-time PCR was employed to evaluate the level of miR-328. Masson’s Trichrome stain was used to evaluate the development of fibrosis. Luciferase activity assay was performed to confirm the miRNA’s binding site in the TGFβRIII gene. Western blot analysis was used to examine TGFβRIII, p-smad2/3 and TGF-β1 at protein level. Results: In this study, we found that miR-328 was significantly upregulated in the border zone of infarcted myocardium of wild type (WT) mice; TGFβRIII was downregulated whereas TGF-β1 was upregulated along with increased cardiac fibrosis. And miR-328 stimulated TGF-β1 signaling and promoted collagen production in cultured fibroblasts. We further found that the pro-fibrotic effect of miR-328 was mediated by targeting TGFβRIII. Additionally, cardiac fibrosis was significantly reduced in infarcted heart when treated with miR-328 antisense. Conclusions: These data suggest that miR-328 is a potent pro-fibrotic miRNA and an important determinant of cardiac fibrosis in diseased heart. [ABSTRACT FROM AUTHOR]

Background/Aims: Acute myocardial infarction (AMI) is a devastating cardiovascular disease with a high rate of morbidity and mortality, partly due to enhanced arrhythmogenicity. MicroRNAs (miRNAs) have been shown to participate in the regulation of cardiac ion channels and the associated arrhythmias. The purpose of this study was to test our hypothesis that miR-223-3p contributes to the electrical disorders in AMI via modulating KCND2, the gene encoding voltage-gated channel Kv4.2 that carries transient outward K+ current Ito. Methods: AMI model was established in male Sprague-Dawley (SD) rats by left anterior descending artery (LAD) ligation. Evans blue and TTC staining was used to measure infarct area. Ito was recorded in isolated ventricular cardiomyocytes or cultured neonatal rat ventricular cells (NRVCs) by whole-cell patch-clamp techniques. Western blot analysis was employed to detect the protein level of Kv4.2 and real-time RT-PCR to determine the transcript level of miR-223- 3p. Luciferase assay was used to examine the interaction between miR-223-3p and KCND2 in cultured NRVCs. Results: Expression of miR-223-3p was remarkably upregulated in AMI relative to sham control rats. On the contrary, the protein level of Kv4.2 and Ito density were significantly decreased in AMI. Consistently, transfection of miR-223-3p mimic markedly reduced Kv4.2 protein level and Ito current in cultured NRVCs. Co-transfection of AMO-223-3p (an antisense inhibitor of miR-223-3p) reversed the repressive effect of miR-223-3p. Luciferase assay showed that miR-223-3p, but not the negative control, substantially suppressed the luciferase activity, confirming the direct binding of miR-223-3p to the seed site within the KCND2 sequence. Finally, direct intramuscular injection of AMO-223-3p into the ischemic myocardium to knockdown endogenous miR-223-3p decreased the propensity of ischemic arrhythmias. Conclusions: Upregulation of miR-223-3p in AMI repressed the expression of KCND2/Kv4.2 resulting in reduction of Ito density that can cause APD prolongation and promote arrhythmias in AMI, and therefore knockdown of endogenous miR-223-3p might be considered a new approach for antiarrhythmic therapy of ischemic arrhythmias. [ABSTRACT FROM AUTHOR]

Background/Aims: Low ambient temperature is an important risk factor for cardiovascular diseases, and has been shown to lead to cardiac hypertrophy. In this study, we aim to investigate if Resveratrol may inhibit cold exposure-induced cardiac hypertrophy in mice, and if so to clarify its molecular mechanism. Methods: Adult male mice were randomly assigned to Control group (kept at room temperature), Cold group (kept at low air temperature range from 3°C to 5°C) and Resveratrol treatment group (100mg/kg/day) for eight weeks. HE staining, Masson staining and Transmission electron microscopy were employed to detect cardiac structure, fibrosis and myocardial ultrastructure, respectively. Echocardiogram was used to measure myocardial functions. Western blot was used to detect the expression of MAPK pathway and apoptotic proteins. TUENL assay was performed to evaluate cardiomyocyte apoptosis. qRT-PCR was employed to measure the mRNA level. Results: Cold-treated mice showed a higher heart/body weight ratio and heart weight/tibia length ratio compared with control mice, and Resveratrol treatment may suppress these changes in cold-treated mice. Myocardial cross-section area and cardiac collagen volume were larger in cold group than control group, which also can be attenuated by Resveratrol treatment. Also, Resveratrol improved the ultrastructure damage of myocardium such as myofibril disarray in cold group. Echocardiogram measurement showed that EF and FS values in cold group declined apparently as compared to control group, and Resveratrol may improve the reduction of heart functions. The expression of p-JNK, p-p38 and p-ERK relative to total JNK, p38 and ERK in cold group was not altered in cold group and Resveratrol group as compared to control group. Cold-treated mouse hearts also showed the upregulation of hypertrophy-related miRNA-miR-328 but not miR-23a, and Resveratrol treatment can inhibit the increase of miR-328. Finally, Resveratrol treatment also may suppress apoptosis of myocardium in cold-treated mouse hearts via inhibiting Bax and caspase-3 activation. Conclusion: In summary, low ambient temperature can cause enlarged heart, ultrastructure damage of myocardium and weakened functions, and Resveratrol treatment effectively suppressed these changes at least partially via inhibiting cardiomyocyte apoptosis. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Several studies have confirmed the role of microRNAs in regulating ischemia/reperfusion-induced cardiac injury (I/R-I). MiR-17-5p has been regarded as an oncomiR in the development of cancer. However, its potential role in cardiomyocytes has not been exploited. The aim of this study is to investigate the role of miR-17-5p in I/R-I and the underlying mechanism through targeting Stat3, a key surviving factor in cardiomyocytes. Methods: MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5 diphenyl tetrazolium bromide) assay was used to detect the cell viability. ELISA and TUNEL were performed to measure apoptosis of neonatal rat ventricular cardiomyocytes (NRVCs). Infarct area was estimated by TTC (triphenyltetrazolium chloride) and Evans blue staining. Western blot analysis was employed to detect the Stat3 and p-Stat3 levels and real-time RT-PCR was used to quantify miR-17-5p level. Results: The miR-17-5p level was significantly up-regulated in I/R-I mice and in NRVCs under oxidative stress. Overexpression of miR-17-5p aggravated cardiomyocyte injury with reduced cell viability and enhanced apoptotic cell death induced by H2O2, whereas inhibition of miR-17-5p by its antisense AMO-17-5p abrogated the deleterious changes. Moreover, the locked nucleic acid-modified antisense (LNA-anti-miR-17-5p) markedly decreased the infarct area and apoptosis induced by I/R-I in mice. Furthermore, overexpression of miR-17-5p diminished the p-Stat3 level in response to H2O2. The results from Western blot analysis and luciferase reporter gene assay confirmed Stat3 as a target gene for miR-17-5p. Conclusion: Upregulation of miR-17-5p promotes apoptosis induced by oxidative stress via targeting Stat3, accounting partially for I/R-I. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Arsenic trioxide (As2O3), an ancient drug used in traditional Chinese medicine, has substantial anticancer activities, especially in the treatment of patients suffering from acute promyelocytic leukemia (APL); however the underlying mechanisms are not well understood. Methods: MTT assay was used to detect the cell viability. Flow Cytometry analysis and caspase-3 activity assay were used to measure apoptosis of APL cells. Caspase-3 and Bax levels were analyzed by western blot and let-7d and miR-766 levels were determined by real-time RT-PCR. Results: As2O3 significantly inhibited cell viability and induced apoptosis in APL cells. Several microRNAs, including let-7d and miR-766, were dysregulated in APL cells treated with As2O3. The expression of caspase-3 and Bax, which are targets of let-7d and miR-766, respectively, were up-regulated in As2O3 treated cells. Transfection of let-7d and miR-766 into NB4 cells decreased the expression of caspase-3 and Bax, respectively. Correspondingly, transfection of these microRNAs increased NB4 cell viability. As2O3 induced degradation of promyelocytic leukemia (PML), and then induced the down-regulation of both let-7d and miR-766 in NB4 cells. Conclusions: We construct a dysregulated microRNA network involved in As2O3-induced apoptosis in APL. Targeting this network may be a new strategy for the prevention of side effects associated with APL treatment with As2O3. © 2014 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background/Aims: Doxorubicin is a widely used chemotherapeutic agent, but its clinical use is restricted because of a high risk of cardiotoxicity. Bone marrow-derived mesenchymal stem cells (BMSCs) may repair ischaemically damaged myocardium through transdifferentiation and paracrine action. The aim of this study is to investigate if doxorubicin causes the apoptosis of BMSCs and in turn impairs its healing ability. Methods: BMSCs were exposed to doxorubicin, and cell apoptosis was determined by western blot and stainings. Results: Doxorubicin reduced the survival ratio and caused the apoptosis of BMSCs, with the increase of intracellular ROS level and depolarization of mitochondrial membrane potential. The ROS scavenger NAC abrogated these consequences. Moreover, doxorubicin markedly activated phosphorylated ERK, p38 and JNK proteins in BMSCs. The specific inhibitors for p38 (SB203580) and JNK (SP600125) may abolish doxorubicin-induced apoptosis of BMSCs but the specific ERK inhibitor (PD98059) not, indicating p38 and JNK activation contribute to BMSCs apoptosis. Also, the phosphorylated and total p53 proteins were increased in doxorubicin-treated BMSCs. Proapoptotic cleaved caspases-3 was upregulated and antiapoptotic Bcl-2 protein was reduced in doxorubicin-treated BMSCs. At last, ELISA assay showed that doxorubicin treatment reduced the VEGF and IGF-1 released by BMSCs. Conclusion: Taken together, doxorubicin caused BMSCs apoptosis associated with p38, JNK and p53 pathways. © 2013 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abnormal QT prolongation is the major cardiac electrical disorder and a predictor of mortality in diabetic patients. Our previous studies suggest that dysfunction of delayed rectifier K+ current (IKr) is the main cause for the problem. Here we report the potential therapeutic role and mechanisms of vitamin E in the rabbit model of diabetes. The QT interval and action potential duration were considerably prolonged with frequent occurrence of ventricular tachyarrhythmias in diabetic rabbits. Administration of vitamin E corrected the abnormal QT prolongation and abolished the arrhythmic incidence. IKr was found markedly reduced resulting in slowing of cardiac repolarization thereby QT prolongation in diabetic hearts. The diabetic depression of IKr is primarily ascribed to oxidative damages to the cardiac membrane and proteins, as indicated by the overproduction of reactive oxygen species leading to severe lipid peroxidation and protein oxidation. Moreover, IKr depression is most likely due to the dysfunction of HERG K+ channel, the major subunit underlying native IKr, in response to oxidative stress, for peroxide anion-generating system produced similar depression of HERG channels. Vitamin E restored the depressed IKr and HERG by its antioxidant actions which likely underlie its beneficial effects on diabetic QT prolongation and the associated arrhythmias. The data indicate that an antioxidant is sufficient for reversing the IKr/IHERG dysfunction and the consequent electrical disorders in diabetic hearts. Our study also conceptually simplifies the complex nature of diabetic electrical disorders to primarily oxidative stress, and should stimulate interest in antioxidants as a therapeutic strategy for diabetic QT prolongation. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Tanshinone IIA is a lipid-soluble compound extracted from Chinese herb Danshen which was commonly used in the treatment of cerebrovascular diseases. Brain iron homeostasis is very essential for normal physiological functions of neurons, and brain iron accumulation contributes to many neurological disorders. The present study was aimed to determine whether Tanshinone IIA protects against cerebral ischemic injury via maintaining brain iron homeostasis. Methods: Wistar Rats were orally administered with Tanshinone IIA (4, 20 and 100 mg/kg/d) for one week, and then subjected to cerebral ischemia by middle cerebral artery occlusion (MCAO) for 2 h. In vitro, cultured neurons were pretreated with Tanshinone IIA (2, 10 and 50 uM) for one week, and then exposed to hypoxia for 24 h. Brain iron content was determined by Flame Atomic Absorption Spectrophotometer and intracellular free iron level was measured by laser scanning Confocal microscopy. Expression levels of iron transport proteins including DMT1, TfR, Fpn1 and Heph were assessed by Western blot technique. Results: Tanshinone IIA pretreatment resulted in a significant reduction of cerebral infarct volume in MCAO rats. Compared with control rats, cerebral ischemia considerably augmented total iron content in the brain of MCAO rats, which was also effectively restricted by Tanshinone IIA pretreatment. MCAO rats exhibited the increased expression of iron influx proteins DMT1 and TfR, and the decreased expression of iron efflux proteins Fpn1 and Heph compared with control rats, which was responsible for elevated iron content in the ischemic brain. Tanshinone IIA pretreatment prevented the dysregulation of these four iron transport proteins and maintained brain iron homeostasis. In vitro studies also confirmed that Tanshinone IIA alleviated the hypoxia-induced decline of cell viability and the overload of intracellular free iron level in neurons through downregulating the expression of DMT1 and TfR, and upregulating the expression of Fpn1 and Heph. Conclusion: Tanshinone IIA protected brain tissues against ischemic and hypoxic damage in vivo and in vitro by mediating brain iron homeostasis which was associated with the downregulation of DMT1 and TfR, and the upregulation of Fpn1 and Heph. These results provide new insights into molecular mechanisms of ischemia-induced brain iron abnormalities and suggest maintaining brain iron homeostasis may be a novel therapeutic strategy for ischemic cerebrovascular diseases. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Tanshinone IIA is a fat-soluble pharmacologically active ingredient of Danshen, a well-known traditional Chinese medicine used for cardiovascular diseases such as coronary heart disease. Tanshinone IIA has been confirmed to suppress miR-1 and reduce the arrhythmogenesis after myocardial infarction (MI). However, the modulation mechanism is not clear. Tanshinone IIA was administrated daily for 7 days before ligation of the left anterior descending artery (LAD) and lasted for 3 months after LAD. Neonatal cardiomyocytes were exposed to 2% O2+95% N2 condition for 24 h to simulate ischemia in vivo. Protein expression was examined with Western blot and miR-1 level was quantified by Real-time PCR. Our results showed that tanshinone IIA relieved ischemia-induced injury by improving the cardiac function. This beneficial effect may due to the depression of the elevated miR-1 level in ischemic and hypoxic cardiomyocytes, which subsequently restored its target Cx43 protein. Furthermore, tanshinone IIA could inhibit activated p38 MAPK and heart special transcription factors SRF and MEF2, in ischemic and hypoxic cardiomyocytes. Pretreatment with p38 MAPK inhibitor, SB203580 (10 uM), significantly relieved hypoxia-induced miR-1 increment and restored its downstream target Cx43 protein expression. These data suggest that tanshinone IIA play a role in protection cardiomyocytes from ischemic and hypoxic injury. The effect is based on inhibiting miR-1 expression through p38 MAPK signal pathway. This might provide us a new target to explore the novel strategy for ischemic cardioprotection. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]