Chronic oral administration of low‐dose combination of fenofibrate and rosuvastatin protects the rat heart against experimentally induced acute myocardial infarction

Fenofibrate and rosuvastatin at low doses might have experimental pleiotropic benefits. This study investigated the combined effect of low doses of fenofibrate and rosuvastatin in isoproterenol‐induced experimental myocardial infarction. Rats administered isoproterenol (85 mg/kg/day, s.c.) for 2 days (day 29 and day 30) of 30 days experimental protocol developed significant myocardial infarction that was accompanied with high myocardial oxidative stress and lipid peroxidation, elevated serum markers of cardiac injury, lipid abnormalities, and elevated circulatory levels of C‐reactive protein. Pretreatment with low doses of fenofibrate (30 mg/kg/day p.o., 30 days) and rosuvastatin (2 mg/kg/day p.o., 30 days) both alone or in combination markedly prevented isoproterenol‐induced myocardial infarction and associated abnormalities while the low‐dose combination of fenofibrate and rosuvastatin was more effective. Histopathological study in isoproterenol control rat heart showed necrosis with edema and acute inflammation at the margins of necrotic area. The rat heart from low‐dose fenofibrate and rosuvastatin pretreated group showed scanty inflammation and no ischemia. In conclusion, fenofibrate and rosuvastatin pretreatment in low doses might have a therapeutic potential to prevent the pathogenesis of myocardial infarction. Moreover, their combined treatment option might offer superior therapeutic benefits via a marked reduction in myocardial infarct size and oxidative stress, suggesting a possibility of their pleiotropic cardioprotective action at low doses.     

Modulation of endoplasmic reticulum stress and cardiomyocyte apoptosis by mulberry leaf diet in experimental autoimmune myocarditis rats

Mulberry is commonly used as silkworm diet and an alternative medicine in Japan and China, has recently reported to contain many antioxidative flavanoid compounds and having the free radical scavenging effects. Antioxidants reduce cardiac oxidative stress and attenuate cardiac dysfunction in animals with pacing-induced congestive heart failure. Hence we investigated the cardioprotective effect of mulberry leaf powder in rats with experimental autoimmune myocarditis. Eight-week-old Lewis rats immunized with cardiac myosin were fed with either normal chow or a diet containing 5% mulberry leaf powder and were examined on day 21. ML significantly decreased oxidative stress, myocyte apoptosis, cellular infiltration, cardiac fibrosis, mast cell density, myocardial levels of sarco/endo-plasmic reticulum Ca(2+) ATPase2, p22(phox), receptor for advanced glycation end products, phospho-p38 mitogen activated protein kinase, phospho-c-Jun NH(2)-terminal protein kinase, glucose regulated protein78, caspase12 and osteopontin levels in EAM rats. These results may suggest that mulberry diet can preserve the cardiac function in experimental autoimmune myocarditis by modulating oxidative stress induced MAPK activation and further afford protection against endoplasmic reticulum stress mediated apoptosis.     

Terminalia arjuna enhances baroreflex sensitivity and myocardial function in isoproterenol-induced chronic heart failure rats

Chronic heart failure (CHF) is characterized by left ventricular (LV) dysfunction along with impaired autonomic control functions. Herbal drugs are increasingly being used in the treatment of cardiovascular disorders. The present study was designed to examine the protective effect of Terminalia arjuna (T arjuna) bark extract on LV and baroreflex function in CHF and to elucidate the possible mechanistic clues in its cardioprotective action. The baroreflex was evaluated by measuring the changes in heart rate (HR) with changes in arterial blood pressure induced by bolus injections of phenylephrine (vasoconstrictor) and sodium nitroprusside (vasodilator). T arjuna bark extract and fluvastatin were tested/administered therapeutically and prophylactically in isoproterenol-induced rat model of CHF. Fifteen days after isoproterenol administration, rats exhibited cardiac dysfunction, hypertrophy, and LV remodeling along with reduced baroreflex sensitivity. Prophylactic and therapeutic treatment with T arjuna improved cardiac functions and baroreflex sensitivity. It also attenuated hypertrophy and fibrosis of the LV. Fluvastatin treatment exerted a similar protective effect against myocardial remodeling and heart failure. Further, T arjuna and fluvastatin significantly reduced oxidative stress and inflammatory cytokine level in CHF rats. In conclusion, T arjuna exerts beneficial effect on LV functions, myocardial remodeling, and autonomic control in CHF possibly through maintaining endogenous antioxidant enzyme activities, inhibiting lipid peroxidation and cytokine levels.     

Aegle marmelos fruit extract attenuates isoproterenol-induced oxidative stress in rats

Myocardial infarction is a major public health concern and the leading cause of death throughout the world. The present study investigates the ability of Aegle marmelos fruit extract to prevent pathological changes and oxidative stress after isoproterenol induced myocardial infarction in rats. In vitro studies showed that Aegle marmelos fruit extract possesses antioxidant activity. Administration of isoproterenol (85 mg/kg body weight) to rats resulted in significantly elevated plasma transaminases, lactate dehydrogenase and creatine kinase, however, cardiac tissue analyses showed decreased activity of the above enzymes compared to experimental control rats. Further, isoproterenol administration significantly increased plasma and cardiac tissue thiobarbituric acid reactive substances and lowered the activities of cardiac tissue superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase and glutathione-S-transferase when compared to control groups. Pretreatment with Aegle marmelos fruit extract at a dose of 150 mg/kg body weight for a period of 45 days significantly prevented the observed alterations. Our data suggest that Aegle marmelos fruit extract exerts its protective effect by decreasing thiobarbituric acid reactive substances and elevating antioxidants status in isoproterenol treated rats. Both biochemical and histopathological results in the isoproterenol-induced myocardial infarction model emphasize the beneficial action of Aegle marmelos fruit extract as a cardioprotective agent.     

Endothelin receptor antagonist BQ-123 ameliorates myocardial ischemic-reperfusion injury in rats: A hemodynamic,biochemical, histopathological and electron microscopic evidence

We investigated the effect of BQ-123, a selective endothelin-A (ET_A) receptor antagonist in ischemia-reperfusion (IR) induced myocardial infarction (MI) with and without endothelin-1 (ET-1) challenge. MI was produced in rats by occlusion of left anterior descending coronary artery for 40 min and reperfusion for 120 min. ET-1 was administered immediately prior to coronary occlusion whereas vehicle or BQ-123 was administered 20 min after the occlusion. IR control group exhibited marked hemodynamic changes along with significant impairment of left ventricular functions. In addition, oxidative stress was increased, as evidenced by marked reduction in the activities of antioxidants and cardiac injury markers in myocardium. Furthermore, light microscopic and ultrastructural changes revealed myocardial necrosis, edema and inflammation. Prior administration of ET-1 acts synergistically with IR injury and further aggravates the impairment of ventricular functions, increased percent infarct area and decreased antioxidant levels. However, treatment with BQ-123 (1 mg/kg, IV) with or without ET-1 caused significant improvement in cardiac functions, percent infarct area, decreased malonaldehyde level, restored myocardial enzymes activities and maintained the redox status of the myocardium as compared to IR control group. Further, histopathological and ultrastructural studies reconfirmed the protective action of BQ-123. The results of present study suggest that ET-1 acting via ET_A receptor may exaggerate myocardial damage produced by IR injury and selective blockade of ET_A receptor by BQ-123 might offer potential cardioprotective action.     

miR-24 inhibits apoptosis and represses Bim in mouse cardiomyocytes

Acute myocardial infarction (MI) involves necrotic and apoptotic loss of cardiomyocytes. One strategy to salvage ischemic cardiomyocytes is to modulate gene expression to promote cell survival without disturbing normal cardiac function. MicroRNAs (miRNAs) have emerged as powerful regulators of multiple cellular processes, including apoptosis, suggesting that regulation of miRNA function could serve a cardioprotective function. In this study, we report that miR-24 (miRNA-24) expression is down-regulated in the ischemic border zone of the murine left ventricle after MI. miR-24 suppresses cardiomyocyte apoptosis, in part by direct repression of the BH3-only domain-containing protein Bim, which positively regulates apoptosis. In vivo expression of miR-24 in a mouse MI model inhibited cardiomyocyte apoptosis, attenuated infarct size, and reduced cardiac dysfunction. This antiapoptotic effect on cardiomyocytes in vivo was partially mediated by Bim. Our results suggest that manipulating miRNA levels during stress-induced apoptosis may be a novel therapeutic strategy for cardiac disease.     

Carvedilol Enhances Mesenchymal Stem Cell Therapy for Myocardial Infarction via Inhibition of Caspase-3 Expression

Adult stem cells have shown great promise toward repairing infarcted heart and restoring cardiac function. Mesenchymal stem cells (MSCs), because of their inherent multipotent nature and their ability to secrete a multitude of growth factors and cytokines, have been used for cardiac repair with encouraging results. Preclinical studies showed that MSCs injected into infarcted hearts improve cardiac function and attenuate fibrosis. Although stem cell transplantation is a promising therapeutic option to repair the infarcted heart, it is faced with a number of challenges, including the survival of the transplanted cells in the ischemic region, due to excessive oxidative stress present in the ischemic region. The objective of this study was to determine the effect of Carvedilol (Carv), a nonselective β-blocker with antioxidant properties, on the survival and engraftment of MSCs in the infarcted heart. MSCs were subjected to a simulated host-tissue environment, similar to the one present in the infarcted myocardium, by culturing them in the presence of hydrogen peroxide (H(2)O(2)) to induce oxidative stress. MSCs were treated with 2.5 μM Carv for 1 h in serum-free medium, followed by treatment with H(2)O(2) for 2 h. The treated cells exhibited significant protection against H(2)O(2)-induced cell death versus untreated controls as determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays. Likewise, transplantation of MSCs after permanent left coronary artery ligation and treatment of animals after myocardial infarction (MI) with Carv (5 mg/kg b.wt.) led to significant improvement in cardiac function, decreased fibrosis, and caspase-3 expression compared with the MI or MSC-alone groups.     

Protective effect of (−)-epigallocatechin-gallate (EGCG) on lipid peroxide metabolism in isoproterenol induced myocardial infarction in male Wistar rats: A histopathological study

This study aims to evaluate the preventive effect of (−)-epigallocatechin-gallate (EGCG) on lipid peroxides, enzymatic and non-enzymatic antioxidants and histopathological findings in isoproterenol (ISO)-induced rats. Myocardial infarction (MI) is induced in rats by subcutaneous injection of ISO (100 mg/kg body weight) at an interval of 24 h for 2 days. ISO-treated rats show a significant increase in the levels of thiobarbituric acid reactive substances, lipid hydroperoxides in plasma and heart and plasma uric acid and a significant decrease in the activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione-S-transferase in heart and the levels of reduced glutathione, vitamin C and vitamin E in plasma and the heart and ceruloplasmin in plasma. Oral pretreatment with EGCG (10, 20 and 30 mg/kg body weight) daily for a period of 21 days show significant decrease in the levels of lipid peroxidation products and uric acid and improved the antioxidant status by increasing the activities of antioxidant enzymes and non-enzymic antioxidants. Histopathological findings of the myocardial tissue show the protective effect of EGCG in ISO-induced rats. The effect at a dose of 30 mg/kg of EGCG was more pronounced than that of the other two doses (10 and 20 mg/kg body weight). Thus, the present study reveals that EGCG exerts cardioprotective effect against ISO-induced MI due to its free radical scavenging and antioxidant effects, which maintains the tissue defense system against myocardial damage.     

Possible involvement of PKC-δ in the abrogated cardioprotective potential of ischemic preconditioning in hyperhomocysteinemic rat hearts

The present study has been designed to investigate the possible role of protein kinase C-delta (PKC-δ) in hyperhomocysteinemia-induced attenuation of cardioprotective potential of ischemic preconditioning (IPC). Rats were administered l-methionine (1.7 g/kg/day, p.o.) for 4 weeks to produce hyperhomocysteinemia. Isolated Langendorff perfused normal and hyperhomocysteinemic rat hearts were subjected to global ischemia for 30 min followed by reperfusion for 120 min. Myocardial infarct size was assessed macroscopically using triphenyltetrazolium chloride (TTC) staining. Coronary effluent was analyzed for lactate dehydrogenase (LDH) and creatine kinase (CK) release to assess the degree of cardiac injury. Moreover, the oxidative stress in heart was assessed by measuring lipid peroxidation and superoxide anion generation. The ischemia-reperfusion (I/R) was noted to produce myocardial injury as assessed in terms of increase in myocardial infarct size, LDH and CK in coronary effluent and oxidative stress in normal and hyperhomocysteinemic rat hearts. In addition, the hyperhomocysteinemic rat hearts showed enhanced I/R-induced myocardial injury with high degree of oxidative stress as compared with normal rat hearts subjected to I/R. Four episodes of IPC (5 min each) afforded cardioprotection against I/R-induced myocardial injury in normal rat hearts as assessed in terms of reduction in myocardial infarct size, LDH, CK and oxidative stress. On the other hand, IPC mediated myocardial protection against I/R-injury was abolished in hyperhomocysteinemic rat hearts. Treatment with rottlerin (10 μM), a selective inhibitor of PKC-δ did not affect the cardioprotective effects of IPC in normal rat hearts; but its treatment significantly restored the cardioprotective potentials of IPC in hyperhomocysteinemic rat hearts. The high degree of oxidative stress produced in hyperhomocysteinemic rat hearts during reperfusion may activate PKC-δ, which may be implicated in the observed paradoxically abrogated cardioprotective potentials of IPC in hyperhomocysteinemic rat hearts.     

Combination renin-angiotensin system blockade and angiotensin-converting enzyme 2 in experimental myocardial infarction: implications for future therapeutic directions

The RAS (renin-angiotensin system) is activated after MI (myocardial infarction), and RAS blockade with ACEis [ACE (angiotensin-converting enzyme) inhibitors] or ARBs (angiotensin receptor blockers) slows but does not completely prevent progression to heart failure. Cardiac ACE is increased after MI and leads to the formation of the vasoconstrictor AngII (angiotensin II). The enzyme ACE2 is also activated after MI and degrades AngII to generate the vasodilator Ang-(1-7) [angiotensin-(1-7)]. Overexpression of ACE2 offers cardioprotective effects in experimental MI, but there is conflicting evidence as to whether the benefits of ACEis and ARBs are mediated through increasing ACE2 after MI. In the present study, we assessed the effect of an ACEi and ARB, alone and in combination, on cardiac ACE2?in a rat MI model. MI rats received vehicle, ACEi (ramipril; 1?mg/kg of body weight), ARB (valsartan; 10?mg/kg of body weight) or combination (ramipril at 1?mg/kg of body weight and valsartan at 10?mg/kg of body weight) orally for 28?days. Sham-operated rats were also studied and received vehicle alone. MI increased LV (left ventricular) mass (P<0.0001), impaired cardiac contractility (P<0.05) and activated cardiac ACE2 with increased gene (P<0.05) and protein expression (viable myocardium, P<0.05; border zone, P<0.001; infarct, P<0.05). Ramipril and valsartan improved remodelling (P<0.05), with no additional effect of dual therapy. Although ramipril inhibited ACE, and valsartan blocked the angiotensin receptor, neither treatment alone nor in combination augmented cardiac ACE2 expression. These results suggest that the cardioprotective effects of ramipril and valsartan are not mediated through up-regulation of cardiac ACE2. Strategies that do augment ACE2 after MI may be a useful addition to standard RAS blockade after MI.     

20(S)-Ginsenoside Rg2 attenuates myocardial ischemia/reperfusion injury by reducing oxidative stress and inflammation: role of SIRT1

Previously we demonstrated that 20(S)-ginsenoside Rg2 protects cardiomyocytes from H₂O₂-induced injury by inhibiting reactive oxygen species (ROS) production, increasing intracellular levels of antioxidants and attenuating apoptosis. We explored the protective effect of 20(S)-ginsenoside Rg2 on myocardial ischemia/reperfusion (MI/R) injury and to clarify its potential mechanism of action. Rats were exposed to 20(S)-ginsenoside Rg2 in the presence/absence of the silent information regulator SIRT(1) inhibitor EX527 and then subjected to MI/R. 20(S)-Ginsenoside Rg2 conferred a cardioprotective effect by improving post-ischemic cardiac function, decreasing infarct size, reducing the apoptotic index, diminishing expression of creatine kinase-MB, aspartate aminotransferase and lactate dehydrogenase in serum, upregulating expression of SIRT1, B-cell lymphoma-2, procaspase-3 and procaspase-9, and downregulating expression of Bax and acetyl (Ac)-p53. Pretreatment with 20(S)-ginsenoside Rg2 also resulted in reduced myocardial superoxide generation, gp91^phox expression, malondialdehyde content, cardiac pro-inflammatory markers and increased myocardial activities of superoxide dismutase, catalase and glutathione peroxidase. These results suggested that MI/R-induced oxidative stress and inflammation were attenuated significantly by 20(S)-ginsenoside Rg2. However, these protective effects were blocked by EX527, indicating that SIRT1 signaling may be involved in the pharmacological action of 20(S)-ginsenoside Rg2. Our results demonstrated that 20(S)-ginsenoside Rg2 attenuates MI/R injury by reducing oxidative stress and inflammatory responses via SIRT1 signaling.

20(S)-Ginsenoside Rg2 confers a protective effect against MI/R injury via SIRT1 signaling, by alleviating oxidative stress and reducing myocardium inflammation.     

Selenium diet-supplementation improves cocaine-induced myocardial oxidative stress and prevents cardiac dysfunction in rats

Chronic cocaine abuse causes cardiac dysfunction and induces oxidative stress. The goal of this study was to evaluate whether an enhanced antioxidant pool, induced by the administration of selenium, may prevent the myocardial dysfunction induced by cocaine. Cocaine was administered for 7 days (15 mg/kg/day, i.p.) to rats pretreated for 4 weeks with selenium (1.16 mg/L/day, p.o.). Cardiac function was evaluated by cardiac index and left ventricular (LV) fractional shortening (FS) measured by echocardiography. The redox ratio and enzymatic activities of glutathione peroxidase (GPX) and superoxide dismutase (SOD) were measured in the LV myocardium. Cocaine administration induced a cardiac dysfunction, as evidenced by a decrease in cardiac index and LV FS as well as by an increase in LV diameters. Moreover, antioxidant markers and redox ratio were altered in rats after cocaine exposure. Selenite supplementation induced a significant limitation of cardiac index and FS alterations observed after cocaine administration. This improvement in cardiac function was associated with a redox ratio recovery while SOD and GPX activities remained unchanged. Thus, selenite reversed both the oxidative stress and the contractile dysfunction induced by cocaine administration. These results suggest a major role of oxidative stress in the cocaine-induced cardiotoxicity.     

Activated protein C protects against myocardial ischemic/reperfusion injury through AMP‐activated protein kinase signaling

Summary. Background: Activated protein C (APC) is a vitamin K‐dependent plasma serine protease that down‐regulates clotting and inflammatory pathways. It is known that APC exerts a cardioprotective effect by decreasing apoptosis of cardiomyocytes and inhibiting expression of inflammatory mediators after myocardial ischemia. Objectives: The objective of this study was to understand the mechanism of the APC‐mediated cardioprotection against ischemic injury. Methods: Cardioprotective activities of wild‐type APC and two derivatives, having either dramatically reduced anticoagulant activity or lacking signaling activity, were monitored in an acute ischemia/reperfusion injury model in which the left anterior descending coronary artery (LAD) was occluded. Results: APC reduced the myocardial infarct size by a mechanism that was largely independent of its anticoagulant activity. Thus, the non‐anticoagulant APC‐2Cys mutant, but not the non‐signaling APC‐E170A mutant, attenuated myocardial infarct size by EPCR and PAR‐1‐dependent mechanisms. Further studies revealed that APC acts directly on cardiomyocytes to stimulate the AMP‐activated protein kinase (AMPK) signaling pathway. The activation of AMPK by APC ameliorated the post‐ischemic cardiac dysfunction in isolated perfused mouse hearts. Moreover, both APC and APC‐2Cys inhibited production of TNFα and IL‐6 in vivo by attenuating the ischemia/reperfusion‐induced JNK and NF‐κB signaling pathways. Conclusions: APC exerts a cardioprotective function in ischemic/reperfusion injury through modulation of AMPK, NF‐κB and JNK signaling pathways.     

Thrombospondin-4, tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14: Novel extracellular matrix modulating factors in cardiac remodelling

Abstract

Cardiac remodelling is defined as changes in the size, shape, and function of the heart, which are most commonly caused by hypertension-induced left ventricular hypertrophy and myocardial infarction. Both neurohumoral and inflammatory factors have critical roles in the regulation of cardiac remodelling. A characteristic feature of cardiac remodelling is modification of the extracellular matrix (ECM), often manifested by fibrosis, a process that has vital consequences for the structure and function of the myocardium. In addition to established modulators of the ECM, the matricellular protein thrombospondin-4 (TSP-4) as well as the tumour necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor Fn14 has been recently shown to modulate cardiac ECM. TSP-4 null mice develop pronounced cardiac hypertrophy and fibrosis with defects in collagen maturation in response to pressure overload. TWEAK and Fn14 belong to the tumour necrosis factor superfamily of proinflammatory cytokines. Recently it was shown that elevated levels of circulating TWEAK via Fn14 critically affect the cardiac ECM, characterized by increasing fibrosis and cardiomyocyte hypertrophy in mice.

Here we review the literature concerning the role of matricellular proteins and inflammation in cardiac ECM remodelling, with a special focus on TSP-4, TWEAK, and its receptor Fn14.     

Chronic beta-adrenergic receptor stimulation induces cardiac apoptosis and aggravates myocardial ischemia/reperfusion injury by provoking inducible nitric-oxide synthase-mediated nitrative stress

The present study provides evidence that inducible nitric-oxide synthase (iNOS)-mediated nitrative stress plays a pivotal role in chronic beta-adrenergic receptor (AR) stimulation-induced cardiac damage. In mice, 14 days of isoproterenol (ISO) stimulation via an osmotic minipump induced an up-regulation of iNOS as evidenced by increases in mRNA, protein expression, and immunochemical staining of myocardial iNOS. Serum level of C-reactive protein, an inflammatory mediator, was also markedly increased. Under chronic ISO stimulation, the up-regulated iNOS produced a significantly increased amount of nitric oxide (NO) and its byproduct, peroxynitrite, in the circulation and heart and subsequently resulted in an accelerated myocardial apoptosis. Forty-minute myocardial ischemia (MI) and 24-h reperfusion (R) further increased NO production and peroxynitrite formation and resulted in an enlarged infarct size in mice receiving chronic ISO stimulation. However, the treatment with a selective iNOS inhibitor [N-(3-(aminomethyl) benzyl)acetamidine] (1400W) or the use of a genetic modified animal (iNOS-knockout mice) markedly reduced iNOS-mediated production of NO and formation of peroxynitrite and consequently significantly decreased myocardial apoptosis and infarct size, showing a crucial link between iNOS-mediated nitrative stress and myocardial injury. In conclusion, chronic beta-AR stimulation up-regulates iNOS expression and increases NO production in the heart, which subsequently markedly enhances formation of reactive nitrogen species/peroxynitrite in the heart, thereby eliciting myocardial apoptosis and potentiating MI/R injury.     

Absence of SPARC results in increased cardiac rupture and dysfunction after acute myocardial infarction

The matricellular protein SPARC (secreted protein, acidic and rich in cysteine, also known as osteonectin) mediates cell–matrix interactions during wound healing and regulates the production and/or assembly of the extracellular matrix (ECM). This study investigated whether SPARC functions in infarct healing and ECM maturation after myocardial infarction (MI). In comparison with wild-type (WT) mice, animals with a targeted inactivation of SPARC exhibited a fourfold increase in mortality that resulted from an increased incidence of cardiac rupture and failure after MI. SPARC-null infarcts had a disorganized granulation tissue and immature collagenous ECM. In contrast, adenoviral overexpression of SPARC in WT mice improved the collagen maturation and prevented cardiac dilatation and dysfunction after MI. In cardiac fibroblasts in vitro, reduction of SPARC by short hairpin RNA attenuated transforming growth factor β (TGF)–mediated increase of Smad2 phosphorylation, whereas addition of recombinant SPARC increased Smad2 phosphorylation concordant with increased Smad2 phosphorylation in SPARC-treated mice. Importantly, infusion of TGF-β rescued cardiac rupture in SPARC-null mice but did not significantly alter infarct healing in WT mice. These findings indicate that local production of SPARC is essential for maintenance of the integrity of cardiac ECM after MI. The protective effects of SPARC emphasize the potential therapeutic applications of this protein to prevent cardiac dilatation and dysfunction after MI.     

Susceptibility of erythrocyte lipids to oxidation and erythrocyte antioxidant status in myocardial infarction

Objective: We evaluated the erythrocyte lipid susceptibility to oxidation and erythrocyte antioxidant status in patients with myocardial infarction (MI).

Design and methods: Patients with MI were divided into two group according to the severity of the disease as severe (n = 30) or milder (n = 25). Malondialdehyde as a marker of lipid peroxidation was measured to show the lipid susceptibility to oxidation. Erythrocytes were stressed in vitro by hydrogen peroxide acting as the oxidative agents for 120 min. After designated time, erythrocyte MDA production was significantly higher in patients with severe MI than in controls and in patients with milder MI (p< 0.001, p< 0.001, respectively). Antioxidant status was determined by measuring the reduced glutathione levels and glutathione peroxidase activity of erythrocyte.

Results: In patients with MI, antioxidant status was significantly lower than in controls, and there was no significant difference between the patient groups.

Conclusion: Determination of erythrocyte lipid susceptibility to oxidation may be a useful in vitro test to evaluate the degree of oxidative stress in myocardial infarction.     

Improved calvarial bone repair by hASCs engineered with Cre/loxP‐based baculovirus conferring prolonged BMP‐2 and MiR‐148b co‐expression

Repairing large calvarial bone defects remains a challenging task. Previously, it was discovered that that miR‐148b, when acting in concert with bone morphogenetic protein 2 (BMP‐2), enhanced the osteogenesis of human adipose‐derived stem cells (hASCs) and improved calvarial bone healing in nude mice. However, the molecular target of miR‐148b remained elusive. Here it is revealed that miR‐148b directly targets NOG, whose gene product (noggin) is an antagonist to BMPs and negatively regulates BMP‐induced osteogenic differentiation and bone formation. A new Cre/loxP‐based baculovirus system was employed to drive prolonged BMP‐2 and miR‐148b overexpression in hASCs, wherein the BMP‐2 overexpression induced noggin expression but the concurrent miR‐148b expression downregulated noggin, thus relieving the negative regulatory loop and ameliorating hASC osteogenesis without hindering hASC proliferation or triggering appreciable cytotoxicity. Implantation of the engineered hASCs coexpressing BMP‐2 and miR‐148b into nude mice enabled substantial repair of critical‐size calvarial bone defects (4 mm diameter) at 12 weeks post‐transplantation, filling 83% of the defect area, 75% of bone volume and restoring the bone density to 89% of the original bone density. Such superior healing effects indicate the potential of the Cre/loxP‐based baculovirus‐mediated BMP‐2/miR‐148b expression for calvarial bone repair. Copyright © 2016 John Wiley & Sons, Ltd.     

Exogenous fetuin-A protects against sepsis-induced myocardial injury by inhibiting oxidative stress and inflammation in mice

Sepsis-induced myocardial injury is a consequence of septicemia and is one of the major causes of death in intensive care units. A serum glycoprotein called fetuin-A is secreted largely by the liver, tongue, placenta, and adipose tissue. Fetuin-A has a variety of biological and pharmacological properties. The anti-inflammatory and antioxidant glycoprotein fetuin-A has shown its efficacy in a number of inflammatory disorders including sepsis. However, its protective role against sepsis-induced myocardial injury remains elusive. The purpose of this work is to explore the role of fetuin-A in mouse models of myocardial injury brought on by cecal ligation and puncture (CLP). CLP significantly induced the myocardial injury assessed in terms of elevated myocardial markers (serum CK-MB, cTnI levels), inflammatory markers (IL-6, TNF-α) in the serum, and oxidative stress markers (increased MDA levels and decreased reduced glutathione) in heart tissue homogenate following 24 h of ligation and puncture. Further, hematoxylin and eosin (H&E) staining showed considerable histological alterations in the myocardial tissue of sepsis-developed mice. Interestingly, fetuin-A pretreatment (50 and 100 mg/kg) for 4 days before the CLP procedure significantly improved the myocardial injury and was evaluated in perspective of a reduction in the CK-MB, cTnI levels, IL-6, and TNF-α in sepsis-developed animals. Fetuin-A pretreatment significantly attenuated the oxidative stress and improved the myocardial morphology in a dose-dependent manner. The present study provides preliminary evidence that fetuin-A exerts protection against sepsis-induced cardiac dysfunction in vivo via suppression of inflammation and oxidative damage.