Chinonin, a novel drug against cardiomyocyte apoptosis induced by hypoxia and reoxygenation

miR-192-5p mediates hypoxia/reoxygenation-induced apoptosis in H9c2 cardiomyocytes via targeting of FABP3

Myocardial ischemia/reperfusion (I/R) injury is a leading cause of morbidity and mortality. In this study, we investigated the role of miR-192-5p in hypoxia/reoxygenation (H/R)-induced cardiomyocyte apoptosis. H9c2 cardiomyocytes were subjected to H/R and tested for miR-192-5p expression. Overexpression and knockdown experiments were performed to determine the effects of manipulating miR-192-5p on apoptotic responses. H/R-treated H9c2 cells exhibited a 2.2-fold increase in miR-192-5p levels. Overexpression of miR-192-5p significantly augmented apoptosis in H9c2 cells after H/R, which was accompanied by a significant increase in the ratio of Bax/Bcl-2. In contrast, delivery of anti-miR-192-5p inhibitors significantly reduced apoptosis induced by H/R. FABP3 was identified to be a functional target of miR-192-5p. Restoration of FABP3 prevented apoptosis in miR-192-5p-transfected H9c2 cells, whereas downregulation of FABP3 enhanced apoptosis in H/R-exposed H9c2 cells. In conclusion, miR-192-5p mediates H/R-induced apoptosis in cardiomyocytes by targeting FABP3 and represents a potential target for prevention of myocardial I/R injury.

Cellular extracts from post-mortem human cardiac tissue direct cardiomyogenic differentiation of human adipose tissue-derived stem cells

BACKGROUND AIMS

Human adipose tissue-derived stem cells (hASCs) can be easily (and inexpensively) expanded in culture, and their high plasticity allows their conversion to different cell types. We study the potential capacity of postmortem cardiac tissue to direct cardiac differentiation of hASCs in vitro.

METHODS

Cardiac tissue collected from autopsies was used to obtain cell extracts and conditioned medium, and both approaches were tested for cardiac induction.

RESULTS

Gene expression analyses proved that post-mortem human cardiac tissue maintains genetic integrity. hASCs exposed to the cell extracts or conditioned medium for 2 weeks achieved the appearance of myotube-like structures and were positive for cardiac markers such as sarcomeric α-actinin, cardiac troponin I and T and desmin as proved by immunofluorescence. In addition, differentiated cells showed increased expression of cardiomyocyte-related genes analyzed by reverse transcriptase polymerase chain reaction (GATA-4, myocyte-enhancer factor-2c, α-cardiac actin and cardiac troponin I).

CONCLUSIONS

For the first time, post-mortem human cardiac tissue was used to induce hASC differentiation into myocardial-like cells. The methodology described here would serve as a useful model to obtain cardiomyocyte-like cells in vitro.

Ginkgo biloba extract (EGb761) inhibits mitochondria-dependent caspase pathway and prevents apoptosis in hypoxia-reoxygenated cardiomyocytes

Background

EGb761 is a standard extract from the leaves of Ginkgo biloba (Yinxing) containing ginkgo-flavone glycosides and terpenoid. The flavonoid components of EGb761 scavenge free radicals and protect myocardia from ischemia-reperfusion injury. The present study aims to determine the effects of the active compounds of EGb761 on mitochondria-dependent caspase pathway.

Methods

Cardiomyocytes were exposed to 24 hours of hypoxia and four hours of reoxygenation, and pretreated with EGb761, bilobalide and quertcetin. By using immunoblot, immunofluorescent, biochemical and flow cytometry techniques, we compared the effects of EGb761 and its representative constituents including quercetin and bilobalides on regulating mitochondria-dependent caspases signal pathway and apoptotic cell death in the hypoxia-reoxygenated cardiomyocytes.

Results

Pretreatment with EGb761 significantly inhibited the release of cytochrome c from mitochondria, the expression of caspase-3, cleavage activities of caspases and attenuated apoptotic cell death. The effects of quercetin on the release of cytochrome c, the cleavage activities of caspases and cell death were similar to those of EGb761 but better than those of bilobalide.

Conclusion

The antioxidant constituents of EGb761 such as quercetin contribute to the cardioprotective effects of EGb761 and inhibit the mitochondria-dependent caspase pathway. It is possible that the mitochondria-dependent caspase pathway may be one of the molecular targets of EGb761 against myocardial ischemia-reperfusion injury.

IGF-1 signaling reduces neuro-inflammatory response and sensitivity of neurons to MPTP

Reduced expression of IGF-1R increases lifespan and resistance to oxidative stress in the mouse, raising the possibility that this also confers relative protection against the pro-parkinsonian neurotoxin MPTP, known to involve an oxidative stress component. We used heterozygous IGF-1R(+/-) mice and challenged them with MPTP. Interestingly, MPTP induced more severe lesions of dopaminergic neurons of the substantia nigra, in IGF-1R(+/-) mice than in wild-type animals. Using electron spin resonance, we found that free radicals were decreased in IGF-1R(+/-) mice in comparison with controls, both before and after MPTP exposure, suggesting that the increased vulnerability of dopamine neurons is not caused by oxidative stress. Importantly, we showed that IGF-1R(+/-) mice display a dramatically increased neuro-inflammatory response to MPTP that may ground the observed increase in neuronal death. Microarray analysis revealed that oxidative stress-associated genes, but also several anti-inflammatory signaling pathways were downregulated under control conditions in IGF-1R(+/-) mice compared to WT. Collectively, these data indicate that IGF signaling can reduce neuro-inflammation dependent sensitivity of neurons to MPTP.

Protective effects of green tea polyphenols in the 6-OHDA rat model of Parkinson's disease through inhibition of ROS-NO pathway

BACKGROUND

Nitric oxide (NO) and related pathways are thought to play an important role in the pathogenesis of Parkinson's disease (PD). Our in vitro experiments suggested that green tea polyphenols (GTP) might protect dopamine neurons through inhibition of NO and reactive oxygen species (ROS).

METHODS

Immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP Nick End Labeling assay, electron spin resonance spin trapping, enzyme linked immunosorbent assay, and molecular biological methods were used to investigate the effects of GTP in an unilateral 6-hydroxydopamine (6-OHDA)-treated rat model of PD.

RESULTS

GTP treatment dose-dependently protected dopaminergic neurons by preventing from midbrain and striatal 6-OHDA-induced increase in 1) both ROS and NO levels, 2) lipid peroxidation, 3) nitrite/nitrate content, 4) inducible nitric oxide synthase, and 5) protein-bound 3-nitro-tyrosine. Moreover, GTP treatment dose-dependently preserved the free radical scavenging capability of both the midbrain and the striatum.

CONCLUSIONS

These results support the in vivo protection of GTP against 6-OHDA and suggest that GTP treatment might represent a neuroprotective treatment of PD.

Differentiation of bone marrow mesenchymal stem cells induced by myocardial medium under hypoxic conditions

AIM

To explore whether bone marrow mesenchymal stem cells (MSC) can differentiate into myocardial-like cells induced by myocardial medium, especially the hypoxia/reoxygenation-conditioned medium of cardiomyocytes.

METHODS

Myocardial cells obtained from neonatal Sprague-Dawley rat ventricles were isolated and cultured in vitro and a hypoxia reoxygenation model was established. The MSC isolated from adult Sprague-Dawley rats were purified and then incubated with 3 different mediums: medium A- the conditioned medium of normal cardiomyocytes; medium B - the conditioned medium of cardiomyocytes after hypoxia reoxygenation; and the control medium - ordinary medium. The expressions of the cardiac myosin heavy chain (MHC), troponin T (TnT) and connexin 43 were investigated in the MSC after 24 h, 48 h and 72 h cultivation, respectively.

RESULTS

The MSC expressed MHC and TnT when incubated with the conditioned medium of cardiomyocytes after hypoxia reoxygenation, but did not express connexin 43. None of MHC, TnT and connexin 43 was detected in the MSC incubated with the conditioned medium of normal cardiomyocytes.

CONCLUSION

The results indicate for the first time that myocardial medium for hypoxic preconditioning can induce MSC differentiation into myocardial-like cells.

Pharmacological Effects of Xanthones as Cardiovascular Protective Agents

Many epidemiological studies indicate that consumption of dietary polyphenolic compounds is beneficial in the prevention of cardiovascular diseases. Xanthones are a class of polyphenolic compounds that commonly occur in plants and have been shown to have extensive biological and pharmacological activities. Recently, the pharmacological properties of xanthones in the cardiovascular system have attracted great interest. Xanthones and xanthone derivatives have been shown to have beneficial effects on some cardiovascular diseases, including ischemic heart disease, atherosclerosis, hypertension and thrombosis. The protective effects of xanthones in the cardiovascular system may be due to their antioxidant, antiinflammatory, platelet aggregation inhibitory, antithrombotic and/or vasorelaxant activities. In particular, the antagonism of endogenous nitric oxide synthase inhibitors by xanthones may represent the basis for improved endothelial function and for reduction of events associated with atherosclerosis.

Hypoxia-reoxygenation-induced apoptosis in cultured neonatal rat cardiomyocyets and the protective effect of prostaglandin E

The aim of the present study was to investigate the effect of prostaglandin (PG) E1 on hypoxia/re-oxygenation (H/R) apoptosis and the expression of bcl-2 and bax in cultured neonatal rat cardiomyocytes. The H/R model was made using the first generation of cultured neonatal rat cardiomyocytes. Hypoxia/re-oxygenation apoptosis was studied by electron microscopy and agarose gel electrophoresis. The percentage of apoptotic cells was measured by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL). The expression of bcl-2 and bax was detected by in situ hybridization and immunohistochemical staining. Most cells of the H/R group tested by electron microscopy showed cytoplasmic concentration, nuclear chromatin condensation and margination. Prostaglandin E1 (5, 15 and 45 microg/L) relieved the injury. The results of DNA electrophoresis in the H/R group showed a typical DNA ladder and the DNA ladder decreased gradually corresponding with increasing doses of PGE1. The TUNEL staining showed that the total number of apoptotic cells in the H/R group was much more than that in the PGE1 (45 microg/L) group. The results of in situ hybridization and immunohistochemical staining showed that the bcl-2 content in the H/R group was lower than that in the control group; bax content showed the reverse. Compared with the H/R group, bcl-2 content was significantly higher in the PGE1 (5, 15 and 45 microg/L) groups. However, bax content in the PGE1 (5, 15 and 45 microg/L) groups was significantly lower than that in the H/R group. 6. In conclusion, H/R injury can induce cardiomyocyte apoptosis. Prostaglandin E1 obviously has anti-apoptotic effects on cardiomyocytes and the mechanisms probably involve the inhibition of bax expression and increased expression of bcl-2.

The role of nitric oxide in anthracycline toxicity and prospects for pharmacologic prevention of cardiac damage

Anthracycline antibiotics are potent antitumor agents whose activity is severely limited by a cumulative dose-dependent chronic cardiotoxicity that results from the summation of multiple biochemical pathways of cellular damage, which ultimately yields to disruption of myocardiocyte integrity and loss of cardiac function. Nitric oxide (NO) is a key molecule involved in the pathophysiology of heart; dysregulation of activity of NO synthases (NOSs) and of NO metabolism seems to be a common feature in various cardiac diseases. The contribution of NO to anthracycline cardiac damage is suggested by evidence demonstrating anthracycline-mediated induction of NOS expression and NO release in heart and the ability of NOSs to promote anthracycline redox cycling to produce reactive oxygen species (ROS), including O2-* and H2O2. Overproduction of ROS and NO yields to reactive nitrogen species, particularly the powerful oxidant molecule peroxynitrite (ONOO-), which may produce the marked reduction of cardiac contractility. This review focuses on the anthracycline-mediated deregulation of NO network and presents an unifying viewpoint of the main molecular mechanisms involved in the pathogenesis of anthracycline cardiotoxicity, including iron, free radicals, and novel mechanistic notions on cardiac ceramide signaling and apoptosis. The data presented in the literature encourage the development of strategies of pharmacological manipulation of NO metabolism to be used as a novel approach to the prevention of cardiotoxicity induced by anthracyclines.

Heparin-binding epidermal growth factor-like growth factor and intestinal ischemia-reperfusion injury

Intestinal ischemia/reperfusion (I/R) injury affects patients of different ages, especially premature babies and the elderly. The outcome after intestinal I/R is often dismal, which may be attributed to loss of the barrier and immune functions of the intestines, as well as development of secondary injury in remote organs. The available treatment for advanced gut ischemia mandates extensive resection, which may cause growth retardation in infants and nutritional problems in the elderly. Throughout the past decade we have been investigating the potential therapeutic role of heparin-binding epidermal growth factor-like factor (HB-EGF) in intestinal I/R. The mitogenic and chemoattractant functions of HB-EGF formed the initial rationale for our investigations. In addition, HB-EGF is a potent antiapoptotic protein that enables cells and tissues exposed to different apoptotic stimuli to survive hypoxic, oxidative, and nutritional stresses. HB-EGF is known to have a vital role in wound healing and postischemic regeneration in different organs. In the current review, we summarize the results of our findings of the beneficial effects of HB-EGF in intestinal I/R, supported by additional evidence from the literature and an explanation of different possible mechanisms of its actions. Collectively, the data strongly suggest a potential therapeutic role for the use of HB-EGF to treat intestinal ischemic diseases such as I/R and necrotizing enterocolitis.

Apoptosis in myocardial ischaemia and infarction

Recent studies indicate that, in addition to necrosis, apoptosis also plays a role in the process of tissue damage after myocardial infarction, which has pathological and therapeutic implications. This review article will discuss studies in which the role and mechanisms of apoptosis in myocardial infarction were analysed in vivo and in vitro in humans and in animals.

Apoptosis in the ischemic reperfused myocardium

Recovery of the myocardium from an ischemic event depends on the reperfusion of the ischemic area. Resumed blood flow to the tissue restores the metabolic substrates necessary for energy production and cell survival. Paradoxically, ischemic reperfusion (I/R) can result in further damage to the myocardium (I/R injury) through an acute inflammatory response mediated by cytokines, neutrophils, macrophages, and reactive oxygen species. These events can trigger cardiomyocyte death through either necrosis or apoptosis. This report will focus on the apoptosis process, which is an organized, active, and gene-directed process of cell self-destruction that can be initiated by intracellular genetic programs, or second messenger pathways inside the cell upon extracellular stimulation by signaling molecules or stress. Awareness of the apoptotic process in cardiomyocytes and endothelial cells is relevant to myocardial preservation during cardiopulmonary bypass compared with off-pump cornary artery bypass procedures. Pharmacological interventions of the signaling pathways that control apoptosis provide an opportunity for new therapeutic approaches to reduce I/R injury in the heart. This review of apoptosis will introduce the perfusionist to apoptosis in the I/R heart, discuss some of the metabolic pathways that initiate it, and report on developing strategies to prevent it.

Chemoprotection from p53-dependent apoptosis: potential clinical applications of the p53 inhibitors

The p53 tumor suppressor pathway is a key mediator of stress response that protects the organism from accumulating genetically altered and potentially cancerous cells by inducing growth arrest or apoptosis in damaged cells. However, under certain stressful conditions, p53 activity can result in massive apoptosis in sensitive tissues, leading to severe pathological consequences for the organism. One such situation is anticancer therapy that is often associated with general genotoxic stress, leading to p53-dependent apoptosis in the epithelia of the digestive tract and in the hematopoietic system. A chemical inhibitor of p53, capable of suppressing p53-mediated apoptosis, was shown to protect mice from lethal doses of gamma-radiation, making pharmacological suppression of p53 a perspective therapeutic approach to reduce the side-effects of cancer treatment. There are other situations, besides anti-cancer therapy, when humans are exposed to stressful conditions known to involve p53 activation, which, in extreme cases, could result in the development of life-threatening diseases. Here we review the experimental evidence on the role of p53 in tissue injuries associated with hypoxia (heart and brain ischemias) and hyperthermia (fever and burns), comparing these pathologies with the consequences of genotoxic stress of cancer treatment. The accumulated information points to the involvement of p53 in the generation of the pathological outcome of the above stresses, making them potential targets for the therapeutic application of p53 inhibitors.

Update on oxygen radical disease in neonatology

An increasing number of articles related to free radicals in the newborn period is published. The hypothesis that there exists a socalled 'Oxygen radical disease of neonatology' has not been proven but an increasing body of evidence seems to indicate that free radicals are involved in several disease processes leading to conditions such as chronic lung disease, retinopathy of prematurity, necrotizing enterocolitis and periventricular leukomalacia. There are also accumulating data implying the involvement of reactive oxygen species and oxidative stress in signal transduction and they therefore perhaps affect growth and development. In the last year there have been no new breakthroughs in antioxidant therapy.

Peroxidatic activity in heart effluent: a biochemical parameter for the assessment of experimental ischemia-reperfusion injury

Peroxidatic activity in heart effluent was defined as a new biochemical parameter for the experimental study of myocardial ischemia. The peroxidatic reaction was determined by dot blot analysis with 3,3'-diaminobenzidine as hydrogen donor. After ischemia, the level of peroxidatic activity in heart effluent was 2-3 times higher than before. The effects in experimental modulation of ischemia, such as nicorandil or aprikalim protection, and the reversibility of protection by glibenclamide, could accurately be noted using the level of peroxidatic activity in heart effluent as a biochemical parameter. The results were in good agreement with those obtained for other enzymes used as biochemical parameters in experimental heart ischemia-reperfusion studies.