Cardiac Protective Effects Research Articles

Abstract 144: Post-myocardial Infarction Therapeutics Using Cardiovascular Progenitor Cells (PC) Derived from Induced Pluripotent Stem Cells (iPSC)

Objective: We sought to assess the cardiac protective effects after MI of (1) PC differentiated directly into cardiomyocytes (CM) and endothelial cells (EC) to the site of injury, or (2) paracrine factors released from PC. Methods: These concepts were evaluated by using iPSC-derived PC genetically modified to express the herpes simplex virus thymidine kinase (TK) under the control of cardiomyocyte (NCX1) or endothelial cell (VE-cadherin) specific promoters. PC expressing the TK permitted ablation at the first week or the third week by iv ganciclovir (GCV). If GCV applied at the first week, but not at the third week, altered cardiac function, we would conclude that myocardial contractile recovery depends on CM and EC-derived from iPSC. If the beneficial effects on cardiac function persisted after GCV was given at the third week, we would surmise that the PC effect was via by a paracrine action. MI created by ligation of LAD, the cell patch with PC was applied to the scarred myocardium. Rats were treated with GCV at 1 or 3 weeks to ablate implanted PC. Echocardiography, vessel density, and histological analysis were used to obtain endpoints for this study. Result: In vivo : The levels of IGF-1α and VEGF released from ischemic tissues were significant higher in the cell patch group. Heart function, infarction size, and vessel density were significantly improved after cell patch treatment. However, this beneficial effect on cardiac function was completely abolished in the group given GCV at week 1, but only partially abolished in the group given GCV at week 3 compared to the untreated cell patch group. Conclusions: Taken together, these data support our conclusion that iPSC-derived cardiovascular lineages (CM and EC) contribute directly to an improved cardiac performance and attenuated remodeling, and that paracrine factors also play a supporting role in the restoration of heart function after MI.

Abstract 38: Important Role of Adiponectin in Volume Overload Induced Heart Failure

Adiponectin (ADP) has been reported to exert cardiac protective effects during ventricular remodeling following pressure overload and myocardial ischemia. However, the potential role of ADP in the volume overload induced heart failure has not been reported. In this study we examined the effect of ADP in cardiac myocyte contractile dysfunction following sustained volume overload. Rat model of volume overload induced heart failure was created by infrarenal aorta-vena cava (A-V) fistula. Some rats were administered with adenoviral ADP (Ad-ADP) at 2-, 6-, and 9-weeks following fistula surgery. Serum total ADP levels were measured at 3 days before, 5 weeks and 10 weeks after fistula surgery. Myocyte contractility and intracellular Ca2+ transients were evaluated at 10 weeks following fistula. Results indicated a progressive reduction of serum ADP levels. In ventricular myocytes isolated from 10-week fistula rats, protein expression of ADP, AdipoR1/R2 and T-cadherin were decreased, and AMPK phosphorylation was reduced. Consistent with these, myocytes exhibited significant depression in cell shortening and intracellular Ca2+ transient. In vivo overexpression of adenovirus-mediated ADP in fistula rats significantly increased ADP serum levels, and prevented the depression of myocyte contractile performance. Moreover, in vitro treatment with ADP significantly improved myocyte contractility and intracellular Ca2+ transient from 10-week fistula rats, but had no effect on myocyte performance in control and Ad-ADP animals. These results demonstrate a positive correlation of ADP reduction and ventricular remodeling induced by volume overload. Adiponectin plays a protective role in volume overload-induced heart failure.

MTORC2 phosphorylation of Akt1: a possible mechanism for hydrogen sulfide-induced cardioprotection.

Hydrogen sulfide (H2S) is known to have cardiac protective effects through Akt activation. Akt acts as a ‘central sensor’ for myocyte survival or death; its activity is regulated by multiple kinases including PI3K, mTORC2, PDK1 and phosphatases including PTEN, PP2A and PHLPPL. Based on the previous finding that PI3K inhibitor LY294002 abolishes H2S-induced Akt phosphorylation and cardioprotection, it is accepted that PI3K is the mediator of H2S-induced Akt phosphorylation. However, LY294002 inhibits both PI3K and mTOR, and PI3K only recruits Akt to the membrane where Akt is phosphorylated by Akt kinases. We undertook a series of experiments to further evaluate the role of mTORC2, PDK1, PTEN, PP2A and PHLPPL in H2S-induced Akt phosphorylation and cardioprotection, which, we believe, has not been investigated before. Hearts from adult Sprague-Dawley rats were isolated and subjected to (i) normoxia, (ii) global ischemia and (iii) ischemia/reperfusion in the presence or absence of 50 µM of H2S donor NaHS. Cardiac mechanical function and lactate dehydrogenase (LDH) release were assessed. All hearts also were Western analyzed at the end of perfusion for Akt and a panel of appropriate Akt regulators and targets. Hearts pretreated with 50 µM NaHS had improved function at the end of reperfusion (Rate pressure product; 19±4×103 vs. 10±3×103 mmHg/min, p<0.05) and reduced cell injury (LDH release 19±10 vs. 170±87 mU/ml p<0.05) compared to untreated hearts. NaHS significantly increased phospho-Akt, phospho-mTOR, phospho-Bim and Bcl-2 in reperfused hearts (P<0.05). Furthermore using H9c2 cells we demonstrate that NaHS pretreatment reduces apoptosis following hypoxia/re-oxygenation. Importantly, PP242, a specific mTOR inhibitor, abolished both cardioprotection and protein phosphorylation in isolated heart and reduced apoptotic effects in H9c2 cells. Treating hearts with NaHS only during reperfusion produced less cardioprotection through a similar mechanism. These data suggest mTORC2 phosphorylation of Akt is a key mediator of H2S-induced cardioprotection in I/R.

β3-Adrenoreceptor stimulation protects against myocardial infarction injury via eNOS and nNOS activation.

β3-adrenergic receptor (AR) and the downstream signaling, nitric oxide synthase (NOS) isoforms, have been emerged as novel modulators of heart function and even potential therapeutic targets for cardiovascular diseases. However, it is not known whether β3-AR plays cardioprotective effects against myocardial infarction (MI) injury. Therefore, the present study was designed to determine the effects of β3-AR on MI injury and to elucidate the underlying mechanism. MI model was constructed by left anterior descending (LAD) artery ligation. Animals were administrated with β3-AR agonist BRL37344 (BRL) or β3-AR inhibitor SR59230A (SR) respectively at 0.1 mg/kg/hour one day after MI operation. The scar area, cardiac function and the apoptosis of myocardial were assessed by Masson's trichrome stain, echocardiography and TUNEL assay respectively. Western blot analysis was performed to elucidate the expressions of target proteins. β3-AR activation with BRL administration significantly attenuated fibrosis and decreased scar area after MI. Moreover, BRL also preserved heart function, and reduced the apoptosis of cardiomyocyte induced by MI. Furthermore, BRL treatment altered the phosphorylation status of endothelial NOS (eNOS) and increased the expression of neuronal NOS (nNOS). These results suggested that β3-AR stimulation has a substantial effect on recovery of heart function. In addition, the activations of both eNOS and nNOS may be associated with the cardiac protective effects of β3-AR.

Selective inhibition of inositol hexakisphosphate kinases (IP6Ks) enhances mesenchymal stem cell engraftment and improves therapeutic efficacy for myocardial infarction.

5-Diphosphoinositol pentakisphosphate (IP7), formed by a family of inositol hexakisphosphate kinases (IP6Ks), has been demonstrated to be a physiologic inhibitor of Akt. IP6K inhibition may increase Akt activation in mesenchymal stem cells (MSCs), resulting in enhanced cardiac protective effect after transplantation. The aim of this study was to investigate the role of IP6Ks for improving MSCs' functional survival and cardiac protective effect after transplantation into infarcted mice hearts. Bone marrow-derived mesenchymal stem cells, isolated from dual-reporter firefly luciferase and enhanced green fluorescent protein positive (Fluc(+)-eGFP(+)) transgenic mice, were preconditioned with IP6Ks inhibitor TNP (0.5, 1, 5, and 10 μmol/L) for 2 h followed by 6 h of hypoxia and serum deprivation (H/SD) injury. TNP concentration dependently significantly decreased IP7 production with increased Akt phosphorylation. Moreover, TNP at 10 μmol/L significantly improved the viability and enhanced the paracrine effect of MSCs after H/SD. Furthermore, MSCs were transplanted into infarcted hearts with or without selective IP6Ks inhibition. Longitudinal in vivo bioluminescence imaging and immunofluorescent staining revealed that TNP pretreatment enhanced the survival of engrafted MSCs, which promoted the anti-apoptotic and pro-angiogenic efficacy of MSCs in vivo. Furthermore, MSC therapy with IP6Ks inhibition significantly decreased fibrosis and preserved heart function. This study demonstrates that inhibition of IP6Ks promotes MSCs engraftment and paracrine effect in infarcted hearts at least in part by down-regulating IP7 production and enhancing Akt activation, which might contribute to the preservation of myocardial function after MI.

Nebivolol protects against myocardial infarction injury via stimulation of beta 3-adrenergic receptors and nitric oxide signaling.

Nebivolol, third-generation β-blocker, may activate β3-adrenergic receptor (AR), which has been emerged as a novel and potential therapeutic targets for cardiovascular diseases. However, it is not known whether nebivolol administration plays a cardioprotective effect against myocardial infarction (MI) injury. Therefore, the present study was designed to clarify the effects of nebivolol on MI injury and to elucidate the underlying mechanism. MI model was constructed by left anterior descending (LAD) artery ligation. Nebivolol, β3-AR antagonist (SR59230A), Nitro-L-arginine methylester (L-NAME) or vehicle was administered for 4 weeks after MI operation. Cardiac function was monitored by echocardiography. Moreover, the fibrosis and the apoptosis of myocardium were assessed by Masson's trichrome stain and TUNEL assay respectively 4 weeks after MI. Nebivolol administration reduced scar area by 68% compared with MI group (p<0.05). Meanwhile, nebivolol also decreased the myocardial apoptosis and improved the heart function after MI (p<0.05 vs. MI). These effects were associated with increased β3-AR expression. Moreover, nebivolol treatment significantly increased the phosphorylation of endothelial NOS (eNOS) and the expression of neuronal NOS (nNOS). Conversely, the cardiac protective effects of nebivolol were abolished by SR and L-NAME. These results indicate that nebivolol protects against MI injury. Furthermore, the cardioprotective effects of nebivolol may be mediated by β3-AR-eNOS/nNOS pathway.

Double-Stranded RNA–Dependent Protein Kinase Deficiency Protects the Heart From Systolic Overload-Induced Congestive Heart Failure

Double-stranded RNA-dependent protein kinase (PKR) is a eukaryotic initiation factor 2α kinase that inhibits mRNA translation under stress conditions. PKR also mediates inflammatory and apoptotic signaling independently of translational regulation. Congestive heart failure is associated with cardiomyocyte hypertrophy, inflammation, and apoptosis, but the role of PKR in left ventricular hypertrophy and the development of congestive heart failure has not been examined. We observed increased myocardial PKR expression and translocation of PKR into the nucleus in humans and mice with congestive heart failure. To determine the impact of PKR on the development of congestive heart failure, PKR knockout and wild-type mice were exposed to pressure overload produced by transverse aortic constriction. Although heart size increased similarly in wild-type and PKR knockout mice after transverse aortic constriction, PKR knockout mice exhibited very little pulmonary congestion, well-preserved left ventricular ejection fraction and contractility, and significantly less myocardial fibrosis compared with wild-type mice. Bone marrow-derived cells from wild-type mice did not abolish the cardiac protective effect observed in PKR knockout mice, whereas bone marrow-derived cells from PKR knockout mice had no cardiac protective effect in wild-type mice. Mechanistically, PKR knockout attenuated transverse aortic constriction-induced tumor necrosis factor-α expression and leukocyte infiltration and lowered cardiac expression of proapoptotic factors (Bax and caspase-3), so that PKR knockout hearts were more resistant to transverse aortic constriction-induced cardiomyocyte apoptosis. PKR depletion in isolated cardiomyocytes also conferred protection against tumor necrosis factor-α- or lipopolysaccharide-induced apoptosis. PKR is a maladaptive factor upregulated in hemodynamic overload that contributes to myocardial inflammation, cardiomyocyte apoptosis, and the development of congestive heart failure.

Chronic Intermittent Hypobaric Hypoxia Ameliorates Ischemia/Reperfusion-Induced Calcium Overload in Heart via Na+/Ca2+ Exchanger in Developing Rats

Background/Aims: Chronic intermittent hypobaric hypoxia (CIHH) protects the heart against ischemia/reperfusion (I/R) injury. This study investigated the calcium homeostasis mechanism and the role of Na⁺/Ca²⁺ exchanger (NCX) in the cardiac protective effect of CIHH in developing rats. Methods: Neonatal male rats received CIHH treatment or no treatment (control) in a hypobaric chamber simulating 3000-meter altitude for 42 days. The left ventricular function of isolated hearts was evaluated after 30 minutes of ischemia and 60 minutes of reperfusion. Myocardial infarct size, intracellular Ca²⁺ concentration ([Ca²⁺]_i), Na⁺-Ca²⁺ exchanger currents (I_Na/Ca) in ventricular myocytes, and NCX1 protein level in the sarcolemmal membrane were determined. Results: The recovery of cardiac function after I/R was improved, with the myocardial infarct size reduced, in CIHH rats compared with control rats (p<0.05). These effects were attenuated by Bay K8644, an L-type Ca²⁺ channel agonist, or ryanodine, a sarcoplasmic reticulum Ca²⁺ channel receptor activator. Furthermore, the increases in [Ca²⁺]_i during I/R were blunted in CIHH rats, but this effect was abolished by Bay K8644 or chelerythrine, a protein kinase C (PKC) inhibitor. The I_Na/Ca was decreased and the reversal potential of I_Na/Ca was shifted toward negative potential during simulated ischemia in the control cardiomyocytes (p<0.05). The inhibition of NCX1 protein expression during I/R was smaller in the CIHH rats than in the control rats (p<0.05). Conclusion: These data suggest that CIHH protects developing rat hearts during I/R by enhancing the resistance against calcium overload and by preserving normal I_Na/Ca and NCX1 protein. PKC activation might be involved in this protective process of CIHH.

Cinacalcet ameliorates cardiac fibrosis in uremic hearts through suppression of endothelial-to-mesenchymal transition

Cardiac fibrosis is a common feature in patients with chronic kidney disease (CKD). Increasing evidence has shown that elevated parathyroid hormone (PTH) is causally involved in cardiac fibrosis [1–4]. Cinacalcet (CINA), a calcimimetic agent, reduces PTH levels without increasing circulating levels of calcium and phosphorus [5,6]. Recent studies have shown that CINA treatment markedly attenuated myocardial fibrosis and vascular remodeling [6,7]. However, the underlying mechanisms of this action are still unknown. Endothelial-to-mesenchymal transition (EndMT) plays an important role in the development of cardiac fibrosis [8,9]. The purpose of this study was to investigate whether CINA ameliorated cardiac fibrosis in rats with uremia was mediated by suppression of EndMT. Study protocols were approved by the Ethical Committee of Southeast University. The rat model of uremia and secondary hyperparathyroidism was established as previously described [10]. Briefly, 8-week-old male Wistar rats were randomly divided into three groups: the control group (CTL, n = 6), the uremia group (U, n = 8) and the CINA-treated uremia group (U + CINA, n = 8). Uremia was induced by feeding rats a 0.75% adenine diet for 4 weeks. After adenine withdrawal, all animals were maintained on a 1.03% phosphorus diet for next 8 weeks. At initiation of the adenine diet, rats in the U + CINA group were orally treated with CINA (Santa Cruz Biotechnology, USA) once daily (10 mg/kg) until the end of experiment. The effect of elevated PTH on EndMT was also studied in primary aortic endothelial cells (ECs). It was demonstrated that the area of cardiac fibrosis in the U group was significantly increased compared to controls, and it was significantly attenuated by the administration of CINA (Fig. 1A–B). And CINA also inhibited the expression of the extracellular matrix elements type I collagen and fibronectin in uremic hearts (Fig. 1C–E). Furthermore, there was significant up-regulation of mesenchymal markers FSP1 and α-SMA, and down-regulation of the endothelial marker CD31, while CINA markedly abrogated expression of EndMT-associated markers in uremic hearts (Fig. 2). Compared with the U group, serum PTH concentrations were significantly lower in uremic rats treated with CINA (440.64 ± 43.25 vs 326.54 ± 47.86, p < 0.05). To further confirm the causal effect of elevated PTH on induction of EndMT, an in vitro experiment with primary aortic ECs was performed. The results showed that PTH incubation increased expression of FSP1 and α-SMA and decreased expression of CD31 at mRNA and protein levels in a concentration and time dependent manner (p < 0.05). Fig. 1 Effect of CINA on fibrotic lesions in uremic hearts. (A) Cardiac fibrosis was assessed by Masson’s trichrome staining. Images with different magnifications are shown. (B) Quantitative determination of cardiac fibrosis in the different groups. ... Fig. 2 Effect of CINA on the expression of EndMT-related markers in uremic hearts. (A) Representative micrographs showing immunohistochemical staining for cardiac expression of CD31 and FSP1 (original magnification is ×200). (B) Representative micrographs ... In conclusion, our data demonstrated that elevation of PTH induces EndMT and contributes to cardiac fibrosis in uremic rats, which could be prevented by CINA treatment. These results suggest that strategies aiming at lowering PTH levels might exert cardiac protective effects through an anti-EndMT mechanism.

Abstract 9321: Selective Inhibition of Inositol Hexakisphosphate Kinases Enhances Mesenchymal Stem Cell Engraftment and Improves Therapeutic Efficacy for Myocardial Infarction

Rationale: 5-diphosphoinositol pentakisphosphate (IP7), formed by a family of inositol hexakis phosphate kinases (IP6Ks), has been demonstrated to be a physiologic inhibitor of Akt. IP6K inhibition may increase Akt activation in mesenchymal stem cells (MSCs), resulting in enhanced cardiac protective effect after transplantation. Objective: To investigate the role of IP6Ks for improving MSCs’ functional survival and cardiac protective effect after transplantation into infarcted mice hearts. Methods and results: Bone marrow-derived mesenchymal stem cells (BMMSCs), isolated from dual-reporter firefly luciferase and enhanced green fluorescent protein positive (Fluc + -eGFP + ) transgenic mice, were preconditioned with IP6Ks inhibitor TNP (0.5μmol/L, 1μmol/L, 5μmol/L, and 10μmol/L) for 2 h followed by 6 hours of hypoxia and serum deprivation (H/SD) injury. TNP dose dependently significantly decreased IP7 production with increased Akt phosphorylation. Moreover,TNP at 10μmol/L significantly improved the viability and enhanced the paracrine effect of MSCs after H/SD. Furthermore, MSCs were transplanted into infarcted hearts with or without selective IP6Ks inhibition. Longitudinal in vivo bioluminescence imaging (BLI) and immunofluorescent staining revealed that TNP pretreatment enhanced the survival of engrafted MSCs, which promoted the anti-apoptotic and pro-angiogenic efficacy of MSCs in vivo . Furthermore, MSCs therapy with IP6Ks inhibition significantly decreased fibrosis and preserved heart function. Conclusion: Inhibition of IP6Ks promotes MSCs engraftment and paracrine effect in infarcted hearts at least in part by down-regulating IP7 production and enhancing Akt activation, which might contribute to the preservation of myocardial function after MI.

TPO plus Tanshinone IIA has neural protective effect and this effect may be mediated via its receptor c-mpl and PI3K/Akt signaling

Thrombopoietin (TPO) is a growth factor for platelet/megakaryocytic lineage. Our previous study showed TPO has cardiac protective effect(Li et al, Circulation, 2006). TPO may also has a protective effect in neural cells. Tanshinone IIA (TIIA), isolated from Danshen (Radix Salviae Miltiorrhiza Bge), is a derivative of phenanthrenequinone, which has been widely used as anti-platelet and neural protection drug for stroke for many years in China. In this study, a hypoxic–ischemic encephalopathy model was established, followed by 2 hrs of hypoxia in 7-day-old neonatal rat pups. TPO (12.5 ug/kg) or/and TIIA (10 mg/kg) were administrated daily (IP) for two weeks. The severity of brain injury was estimated by the weight reduction of the ipsilateral cerebral hemisphere as compared to the contralateral hemisphere. There was significant less atrophy in TPO alone or TPO plus TIIA treated animals compared with that in controls at 7 and 21 days (P<0.05, n=8). The loss of neurons in the forelimb area of the cortex was also reduced after TPO or TPO plus TIIA treatment. NSE positive cells in the forelimb area of the cortex in the right hemisphere was significantly higher in the treatment group than that of the saline group (P<0.05, n=8). An improvement in sensory motor functions was also demonstrated after TPO or TPO plus TIIA treatment. Furthermore, TPO receptor (c-mpl) mRNA was identified in human cerebral hemispheres and cerebellum, and C17.2 cell line using RT-PCR. The expression of c-mpl protein was further confirmed in human cerebral hemispheres, hippocampus, cerebellum, brainstem and spinal cord using immunocytochemical staining. Its ligang TPO was also detected in human cerebrospinal fluids (n=10) by ELISA, and TPO mRNA was expressed in human cerebral hemispheres, cerebellum, and mouse neural stem cell line C17.2 by RT-PCR methods. TPO showed an anti-apoptotic effect on C17.2 cells by the AnnexinV/PI assay. Moreover, TPO activated PI3K/Akt signaling pathway which was demonstrated by Western blot. The Akt activation by TPO was inhibited by the PI3-kinase inhibitor LY294002. This study provided the evidences showing that TPO or TPO plus TIIA has neural protective effect and this effect may be mediated via its receptor c-mpl, then activated PI3K/Akt signaling. Disclosures:No relevant conflicts of interest to declare.

TPO exerts a protective effect on iron-overload induces apoptosis in cardiomyocytes via mitochondrial pathways

Thalassaemia companied with iron-overload is common in Hong Kong. Iron overload induced cardiomyopathy is the commonest cause of morbidity and mortality in b-thalassaemia patients. One of the causes of cardiac failure is chronic iron overload of blood transfusion. Some studies showed that iron overload can cause toxic effect in heart cells. Iron-overload induced cardiomyopathy damages are the major complications in patients with beta-thalassaemia major. Iron-overload may induce apoptosis in cardiomyocytes. Our previous study showed TPO has cardiac protective effect (Li et al, Circulation, 2007). In this study, we demonstrated firstly that iron induced oxidative stress can cause apoptosis in cardiomyocytes. By using H9C2 cells, we showed that iron increased reactive oxygen species (ROS) production (n=3) and reduced cell viability in a dose-dependent manner (0-0.6 mM) (n=6). Apoptotic cells were found to be significantly increased under iron treatment (0.3 mM, 72 hrs) in the AnnexinV/PI assay (n=6). The expression of active caspase-3 significantly increased in iron-treated cells. Furthermore, iron treatment increased the proportion of cells containing JC-1 monomers, indicating a trend in the drop of mitochondrial membrane potential (n=6). Secondly, we found that TPO exerted cardio-protective effect on iron-induced apoptosis. H9C2 cells were cultured in the presence of iron (0.3 mM) with or without TPO (50 ng/mL). The ROS production was significantly decreased with the addition of TPO at 50 ng/mL (n=3). Dot-plot analysis of AnnexinV/PI staining demonstrated that TPO significantly reduced the population of apoptotic cells (n=6). Incubation with TPO also decreased the iron-induced caspase-3 expression (n=6). Flow cytometric dot-plot analysis also showed trends of amelioration of the increase in JC-1 monomers in the iron plus TPO group (n=6), indicating a trend in attenuation of the drop of mitochondrial membrane potential. Our findings suggest that iron-overload lead to generation of ROS which further induces apoptosis in cardiomyocytes via mitochondrial pathways and TPO might exert a protective effect on iron-overload induced apoptosis via inhibiting oxidative stress and mitochondrial pathway in cardiomyocytes. Disclosures: No relevant conflicts of interest to declare.

Effects of Thymoquinone on STZ-induced Diabetic Nephropathy: An Immunohistochemical Study

Background: Thymoquinone (TQ) is the most abundant and active ingredient of Nigella sativa (NS) seeds. Its hepatic, renal, and cardiac protective effects have been demonstrated in animal models. Streptozotocin (STZ) is an antibiotic that is widely used experimentally as an agent capable of inducing insulin-dependent diabetes mellitus (IDDM), also known as type I diabetes mellitus (T1DM).Objectives: This study was carried out in an attempt to highlight the possible beneficial effects of TQ in STZ-induced diabetes in rats and to determine the predictive value of mesenchymal and epithelial markers in the response of diabetic nephropathy to TQ.Materials and Methods: Sixty adult male albino rats were divided in 3 groups: control, diabetic untreated, and diabetic treated with TQ.Results: Diabetic rats exhibited morphological changes in both renal glomeruli and tubules with immunohistochemical expression of the mesenchymal markers Fsp1, desmin, and MMP-17 and disappearance of the epithelial marker ZO-1 largely in the glomeruli of diabetic kidneys. Treatment with TQ significantly attenuated renal morphological and immunohistochemical changes in STZ-induced diabetic rats.Conclusions: Thymoquinone has protective effects on experimental diabetic nephropathy. Both mesenchymal and epithelial markers serve as excellent predictors of early kidney damage and indicators of TQ responsiveness in STZ-induced diabetic nephropathy.

Cyclic nucleotide phosphodiesterase 3A1 protects the heart against ischemia-reperfusion injury

Phosphodiesterase 3A (PDE3A) is a major regulator of cAMP in cardiomyocytes. PDE3 inhibitors are used for acute treatment of congestive heart failure, but are associated with increased incidence of arrhythmias and sudden death with long-term use. We previously reported that chronic PDE3A downregulation or inhibition induced myocyte apoptosis in vitro. However, the cardiac protective effect of PDE3A has not been demonstrated in vivo in disease models. In this study, we examined the role of PDE3A in regulating myocardial function and survival in vivo using genetically engineered transgenic mice with myocardial overexpression of the PDE3A1 isozyme (TG). TG mice have reduced cardiac function characterized by reduced heart rate and ejection fraction (52.5±7.8% vs. 83.9±4.7%) as well as compensatory expansion of left ventricular diameter (4.19±0.19mm vs. 3.10±0.18mm). However, there was no maladaptive increase of fibrosis and apoptosis in TG hearts compared to wild type (WT) hearts, and the survival rates also remained the same. The diminution of cardiac contractile function is very likely attributed to a decrease in beta-adrenergic receptor (β-AR) response in TG mice. Importantly, the myocardial infarct size (4.0±1.8% vs. 24.6±3.8%) and apoptotic cell number (1.3±1.0% vs. 5.6±1.5%) induced by ischemia/reperfusion (I/R) injury were significantly attenuated in TG mice. This was associated with decreased expression of inducible cAMP early repressor (ICER) and increased expression of anti-apoptotic protein BCL-2. To further verify the anti-apoptotic effects of PDE3A1, we performed in vitro apoptosis study in isolated adult TG and WT cardiomyocytes. We found that the apoptotic rates stimulated by hypoxia/reoxygenation or H2O2 were indeed significantly reduced in TG myocytes, and the differences between TG and WT myocytes were completely reversed in the presence of the PDE3 inhibitor milrinone. These together indicate that PDE3A1 negatively regulates β-AR signaling and protects against I/R injury by inhibiting cardiomyocyte apoptosis.

Exercise training upregulates nitric oxide synthases in the kidney of rats with chronic heart failure

There is an interaction between heart and kidney diseases, which is a condition termed cardiorenal syndrome. Exercise training has cardioprotective effects, involving upregulation of endothelial (e) nitric oxide synthase (NOS) in the cardiovascular system. However, the effects of exercise training on NOS in the kidney with heart disease are unknown. The aim of the present study was to investigate whether exercise training upregulates NOS in the kidney, left ventricle and aorta of rats with chronic heart failure (CHF). Male Sprague-Dawley rats underwent left coronary artery ligation (LCAL) to induce CHF and were randomly assigned to sedentary or treadmill exercise groups 4 weeks after LCAL. Three days after exercising for 4 weeks, urine samples were collected for 24 h and blood samples were collected following decapitation. Nitric oxide synthase activity and protein expression were examined. Significant interactions between CHF and exercise training were observed on parameters of cardiac and renal function. Exercise training improved cardiac function, decreased plasma B-type natriuretic peptide levels, decreased urinary albumin excretion and increased creatinine clearance in CHF rats. Nitric oxide synthase activity, eNOS expression and neuronal (n) NOS expression were significantly decreased in the left ventricle and kidney of CHF rats. Exercise training significantly increased NOS activity and eNOS and nNOS expression. Upregulation of NOS in the kidney and left ventricle may contribute, in part, to the renal and cardiac protective effects of exercise training in cardiorenal syndrome in CHF rats.

Cardiac protective effect of adjunctive trimetazidine therapy in primary angioplasty for acute ST-segment elevation myocardial infarction

Cardiac protective effect of adjunctive trimetazidine therapy in primary angioplasty for acute ST-segment elevation myocardial infarction

GW24-e2454 Renal sympathetic denervation impact the expression of MMP-2,9 in myocardium

ObjectivesTo observed the protective effects of Renal sympathetic denervation (RSD) on myocardial interstitial remodelling, By detected the expression level of MMP-2,9 in infarcted border zone (IBZ), myocardial infarcted zone (MIZ)...

Abstract 321: Deletion Of The Translational Repressors Eukaryotic Translation Initiation Factor 4e Binding Proteins 1 And 2 Protects Against Pressure Overload Induced Heart Failure

Assembly of the translation initiation machinery is negatively regulated by the eukaryotic translation initiation factor 4E binding proteins, which sequester the mRNA cap-binding protein eIF4E, thus preventing assembly of an intact initiation complex. However, the role of translational control on the development of congestive heart failure (CHF) has not been systematically examined. Here we perturbed translational control in mice by knockout of both 4E binding protein 1 (Eif4ebp1) and 2 (Eif4ebp2) (designated as Eif4ebp1/2 double knockout) to study its impact on left ventricular hypertrophy and CHF resulting from transverse aortic constriction. Eif4ebp1/2 double knockout caused a modest increase in left ventricular mass under basal conditions. However, following transverse aortic constriction, Eif4ebp1/2 double knockout profoundly attenuated the development of CHF and its attendant mortality. Examination of candidate genes involved in the mechanism revealed increased expression of transcription factors for genes governing energy metabolism and mitochondrial biogenesis with corresponding increases in the expression of their target genes. Our data indicate that removing physiological restraints on translation initiation exerts a profound cardiac protective effect against pressure overload induced CHF, suggesting that method(s) to disrupt the function of the 4E binding proteins may be a novel therapeutic approach for preventing or treating CHF.

Searching for Phytoinsulins as Cardiovascular Protector in Metabolic Syndrome

Metabolic syndrome is well known to increase the risk of cardiovascular disease and diabetes. As the key feature of metabolic syndrome, insulin resistance occurs when target tissues cannot respond properly to insulin and develops in multiple organs, including the vasculature and heart. Accumulating evidence has suggested insulin-induced PI3K-Akt-eNOS survival signaling as a potent therapeutic target for cardiovascular disorders and highlighted the impaired survival signaling as a key link between insulin resistance and cardiovascular disease. However, long-term insulin treatment is inconvenient and may increase the risk of hypoglycemia. More importantly, the effects of insulin are significantly blunted in patients with insulin resistance due to the pathway-specific impairment of PI3K-Akt signaling, and exogenous chronic insulin administration may lead to the over-activation of Ras-MAPK signaling which may result in unwanted side effects. Our recent study has shown that some Chinese medicinal herbs can directly activate PI3K-Akt-eNOS survival signals and improve tissue insulin sensitivity to exert endothelial and cardiac protective effects in diabetic animals. These herbs or phytoinsulins as we named, targeting insulin-activated cell survival signals and exert insulin-like actions, have promising beneficial effects on prevention and treatment of diabetes- and insulin resistance-induced cardiovascular disorders. Another advantage of phytoinsulins is that they generally exert multiple actions, including mild blood glucose-lowering effect, pancreatic β cells protection and adipogenesis reduction, for better cardiovascular protection. In this review, we discussed our strategies of searching for phytoinsulins and their potential beneficial effects in the treatment of metabolic syndrome, especially their values in prevention of diabetic cardiovascular disease.

Isorhamnetin protects against doxorubicin-induced cardiotoxicity in vivo and in vitro.

Doxorubicin (Dox) is an anthracycline antibiotic for cancer therapy with limited usage due to cardiotoxicity. Isorhamnetin is a nature antioxidant with obvious cardiac protective effect. The aim of this study is going to investigate the possible protective effect of isorhamnetin against Dox-induced cardiotoxicity and its underlying mechanisms. In an in vivo investigation, rats were intraperitoneally (i.p.) administered with Dox to duplicate the model of Dox-induced chronic cardiotoxicity. Daily pretreatment with isorhamnetin (5 mg/kg, i.p.) for 7 days was found to reduce Dox-induced myocardial damage significantly, including the decline of cardiac index, decrease in the release of serum cardiac enzymes and amelioration of heart vacuolation. In vitro studies on H9c2 cardiomyocytes, isorhamnetin was effective to reduce Dox-induced cell toxicity. A further mechanism study indicated that isorhamnetin pretreatment can counteract Dox-induced oxidative stress and suppress the activation of mitochondrion apoptotic pathway and mitogen-activated protein kinase pathway. Isorhamnetin also potentiated the anti-cancer activity of Dox in MCF-7, HepG2 and Hep2 cells. These findings indicated that isorhamnetin can be used as an adjuvant therapy for the long-term clinical use of Dox.