Rat Model Of Dilated Cardiomyopathy Research Articles

Infusion of two-dose mesenchymal stem cells is more effective than a single dose in a dilated cardiomyopathy rat model by upregulating indoleamine 2,3-dioxygenase expression

Background and aimsThe therapeutic efficacy of single-dose mesenchymal stromal cell (MSC) therapy for heart failure (HF) remains inconsistent. This study aimed to investigate whether infusion with two-dose human umbilical cord MSC (hUCMSCs) could be therapeutically superior to single-dose therapy in a rat model of dilated cardiomyopathy (DCM) and explored the underlying mechanisms.MethodsMale Sprague–Dawley rats were intraperitoneally injected with doxorubicin (DOX) to establish a DCM model and randomized to intravenously receive single-dose or two-dose hUCMSCs at an interval of 14 days. Their left ventricular (LV) systolic and diastolic functions were analyzed by echocardiography. The percentages of Th1, Th2, Th17, and Treg cells in the heart, spleen, lymph nodes, and peripheral blood and the levels of serum cytokines in individual rats were analyzed by flow cytometry and cytometric bead assay, respectively. The degrees of cardiac fibrosis and cardiomyocyte apoptosis were examined by histology. The importance of indoleamine 2,3-dioxygenase (IDO), an activator of Treg differentiation, in the therapeutic effect of hUCMSCs on inflammation and heart function of rats was determined after induction of IDO over-expression (IDO-OE) using IFN-γ (1 ng/ml) and TNF-α (10 ng/ml) stimulation or silencing (IDO-KD) using small interfering RNA (siRNA) technology.ResultsCompared with the single dose, two-dose hUCMSCs were more effective in improving LV performance, attenuating cardiac dilation, reducing cardiomyocyte apoptosis and cardiac fibrosis. Two-dose hUCMSC therapy significantly increased Treg number in the heart and peripheral blood, accompanied by increased cardiac IDO expression. Compared with the control hUCMSCs, IDO-OE hUCMSCs significantly enhanced Treg and Th2 cell responses and decreased systemic Th17 cell responses and Th1 cell numbers in the mediastinal lymph nodes. Treatment with IDO-OE hUCMSCs significantly improved LV remodeling and dysfunction. However, treatment with IDO-KD hUCMSCs had opposite effects in rats.ConclusionsAdministration of two-dose hUCMSCs has better therapeutic effects than single-dose therapy for inhibiting myocardial inflammation to improve LV function in DCM rats. These effects are associated with upregulating IDO expression and its systemic anti-inflammatory activities.

Effect of trimetazidine combined with perindopril on NT-proBNP level in rats with dilated cardiomyopathy

This experiment aimed to study the effect of trimetazidine combined with perindopril on NT-proBNP levels in rats with dilated cardiomyopathy (DCM). 40 SD rats were selected and 10 rats were randomly selected to continue to be fed as the blank group. The other 30 rats were injected with adriamycin to establish the DCM rat model. Then they were divided into 3 groups, namely control group (without any drug intervention), trimetazidine group (with trimetazidine single-agent intervention) and combination drug group (with trimetazidine combined with perindopril intervention), with 10 DCM rats in each group. After 4 weeks of intervention, left ventricular ejection fraction (LVEF), left ventricular end-diastolic dimension (LVEDD) and left ventricular end-systolic diameter (LVESD) of rats were measured by echocardiography. The changes of plasma brain natriuretic peptide (BNP) level and n-terminal pro-brain natriuretic peptide (NT-proBNP) were detected by ELISA. RT-PCR was used to detect the regulation of angiotensin II type 1 receptor (AT1Rs) and lamin A mRNA expression in rat myocardium. After the intervention, the LVEF%, LVEDD and LVESD measured values of the rats in the combination drug group were significantly better than those in the trimetazidine group and the control group (P< 0.05). The BNP, NT-proBNP and AT1Rs levels of the rats in the combination drug group were significantly lower than those in the trimetazidine group and the control group. The difference was statistically significant (p< 0.05). The lamin A expression of the rats in the combination drug group was significantly higher than that in the trimetazidine group and the control group. The difference was statistically significant (P< 0.05). Compared with trimetazidine single-agent, trimetazidine combined with perindopril can significantly improve the cardiac function of rats with dilated cardiomyopathy, reduce the serum NT-proBNP level and improve the expression of AT1Rs and lamin A in rats.

LTBP2 knockdown by siRNA reverses myocardial oxidative stress injury, fibrosis and remodelling during dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is characterised by left ventricular dilation and associated with systolic dysfunction. Recent evidence has reported the high expression of latent transforming growth factor beta binding protein 2 (LTBP2) in heart diseases, which may play a role in regulating multiple biological functions of myocardial cells. Thus, this study set out to investigate the molecular mechanism and effects of LTBP2 in myocardial oxidative stress injury, fibrosis and remodelling in a rat model of DCM, with the involvement of NF-κB signalling pathway. The rat model of DCM was treated with si-LTBP2 and/or activator of NF-κB signalling pathway to examine the haemodynamic indexes, cardiac functions, oxidative stress injury, fibrosis and remodelling. Moreover, in vitro experiments were conducted to verify the regulatory role of LTBP2 and NF-κB signalling pathway in DCM. LTBP2 was up-regulated in DCM rats. After LTBP2 was knocked down, haemodynamic indexes, HW/BW ratio, collagen volume fraction (CVF) level, positive expression of LTBP2, levels of reactive oxygen species (ROS), malondialdehyde (MDA), interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-α), tumour necrosis factor beta 1 (TGF-β1) and brain natriuretic peptide (BNP) were all decreased. Meanwhile, levels of LTBP2, Col-I, Col-III, p65 and p52 were also reduced, while HW, BW and levels of SOD and TAOC were increased. In contrast, activation of NF-κB signalling pathway reversed effects of LTBP2 gene silencing. These findings were confirmed by in vivo experiments. LTBP2 silencing can attenuate myocardial oxidative stress injury, myocardial fibrosis and myocardial remodelling in DCM rats by down-regulating the NF-κB signalling pathway.

Effect of bilateral sympathectomy in a rat model of dilated cardiomyopathy induced by doxorubicin

ObjectiveThe study objective was to evaluate the effect of bilateral sympathectomy on ventricular remodeling and function in a rat model of dilated cardiomyopathy induced by doxorubicin. MethodsDilated cardiomyopathy was induced in male Wistar rats by weekly intraperitoneal injection of doxorubicin (2 mg/kg) for 9 weeks. Animals were divided into 4 groups: dilated cardiomyopathy; bilateral sympathectomy, submitted on day 15 of the protocol to bilateral sympathectomy; angiotensin-converting enzyme inhibitor, treated with enalapril through day 15 until the end of the experimental protocol; and sham, nonsubmitted through doxorubicin protocol, with weekly intraperitoneal injections of saline solution (0.9%). The left ventricular function was assessed, and the heart was collected for posterior analyses. ResultsThe dilated cardiomyopathy group presented a significant decrease in the myocardial efficiency when compared with the sham group (33.4% vs 71.2%). Only the bilateral sympathectomy group was able to preserve it (57.5%; P = .0001). A significant dilatation in the left ventricular chamber was observed in the dilated cardiomyopathy group (15.9 μm2) compared with the sham group (10.2 μm2; P = .0053). Sympathectomy and enalapril prevented ventricular remodeling (9.5 and 9.6 μm2, respectively; P = .0034). There was a significant increase in interstitial myocardial fibrosis in the dilated cardiomyopathy group (14.8%) when compared with the sham group (2.4%; P = .0001). This process was significantly reduced with sympathectomy and enalapril (8.7 and 3.9%, respectively; P = .0001). ConclusionsBilateral sympathectomy was effective in preventing remodeling and left ventricular dysfunction in a rat model of dilated cardiomyopathy induced by doxorubicin.

Effect of Shenqi Yangxin decoction on high mobility group box 1 and inflammatory signal pathway in a rat model of dilated cardiomyopathy

OBJECTIVETo investigate the effects of Shenqi Yangxin decoction (SQYXD) on heart function in a rat model of dilated cardiomyopathy (DCM) and its potential mechanisms. METHODSSprague-Dawley rats were randomly divided into normal (10 rats) and DCM (150 rats) groups. DCM was induced by an intraperitoneal injection of adriamycin. Then, DCM baseline group was randomly selected sixteen DCM rats. The remaining DCM rats were randomly divided into DCM control, perindopril, metoprolol, and SQYXD groups. Cardiac function and histological analysis plus biochemical measurement of serum levels of brain natriuretic peptide (BNP), and inflammatory factors were measured. The mRNA and protein expression levels of high-mobility group box 1 (HMGB1), Toll-like receptor 4 (TLR-4), receptor for advanced glycation end products (RAGE), and nuclear factor-κB (NF-κB) were determined. Myocardial metabolism imaging was performed on the normal, SQYXD and DCM control groups to evaluate the effectiveness of treatments. RESULTSRats in the DCM control group exhibited dilated left ventricular diameter, impaired cardiac function, disorganized sarcomere, impaired glucose metabolism, increased heart weight index, and increased levels of BNP, which were improved by treatment with SQYXD. In addition, hearts from rats in the DCM baseline group exhibited significantly higher levels of HMGB1, TLR-4, RAGE, NF-κB, tumor necrosis factor-α, interleukin-1, interleukin-6, interleukin-10, compared with the normal group. Interestingly, the mRNA level of HMGB1 in the DCM baseline group was positively correlated with that of TLR-4, RAGE, NF-κB, BNP, and LVEDD, but negatively correlated with LVEF. SQYXD inhibited the upregulation of HMGB1 expression and its downstream inflammatory factors. CONCLUSIONShenqi Yangxin decoction effectively reduced the dilated left ventricular diameter and improved heart function in dilated cardiomyopathy. The mechanisms underlying the action on DCM involve regulating the gene and protein expression of HMGB1 and its inflammatory signal pathways in the DCM rat model.

Human umbilical cord mesenchymal stem cells alleviate interstitial fibrosis and cardiac dysfunction in a dilated cardiomyopathy rat model by inhibiting TNF‑α and TGF‑β1/ERK1/2 signaling pathways.

Dilated cardiomyopathy (DCM) is a disease of the heart characterized by pathological remodeling, including patchy interstitial fibrosis and degeneration of cardiomyocytes. In the present study, the beneficial role of human umbilical cord-derived mesenchymal stem cells (HuMSCs) derived from Wharton's jelly was evaluated in the myosin-induced rat model of DCM. Male Lewis rats (aged 8-weeks) were injected with porcine myosin to induce DCM. Cultured HuMSCs (1×106 cells/rat) were intravenously injected 28 days after myosin injection and the effects on myocardial fibrosis and the underlying signaling pathways were investigated and compared with vehicle-injected and negative control rats. Myosin injections in rats (vehicle group and experimental group) for 28 days led to severe fibrosis and significant deterioration of cardiac function indicative of DCM. HuMSC treatment reduced fibrosis as determined by Masson's staining of collagen deposits, as well as quantification of molecular markers of myocardial fibrosis such as collagen I/III, profibrotic factors transforming growth factor-β1 (TGF-β1), tumor necrosis factor-α (TNF-α), and connective tissue growth factor (CTGF). HuMSC treatment restored cardiac function as observed using echocardiography. In addition, western blot analysis indicated that HuMSC injections in DCM rats inhibited the expression of TNF-α, extracellular-signal regulated kinase 1/2 (ERK1/2) and TGF-β1, which is a master switch for inducing myocardial fibrosis. These findings suggested that HuMSC injections attenuated myocardial fibrosis and dysfunction in a rat model of DCM, likely by inhibiting TNF-α and the TGF-β1/ERK1/2 fibrosis pathways. Therefore, HuMSC treatment may represent a potential therapeutic method for treatment of DCM.

Comparative evaluation of torasemide and spironolactone on adverse cardiac remodeling in a rat model of dilated cardiomyopathy

Chronic heart failure (CHF) involves fluid retention and volume overload, leading to impaired cardiac function. In these conditions, diuretic agents are most commonly used to treat edema and thereby reducing the volume load on the failing heart. There are several other beneficial effects of diuretics apart from their action on urinary excretion. To identify the effects of diuretic agents on adverse cardiac remodeling in CHF, this study was carried out, where we have compared the effects of torasemide and spironolactone in a rat model of dilated cardiomyopathy induced by porcine cardiac myosin-mediated experimental autoimmune myocarditis. Cardiac protein expression levels of inflammation, endoplasmic reticulum stress, and fibrosis markers were upregulated in the hearts of CHF rats, while treatment with either torasemide or spironolactone has downregulated their expression. The effect produced by spironolactone on cardiac fibrosis markers was comparably lesser than torasemide. Further, immunohistochemical analysis and histopathological studies have provided evidence to confirm the beneficial effects of these drugs on adverse cardiac remodeling in rats with CHF. Torasemide treatment has benefits against adverse cardiac remodeling in CHF rats, which was better than the protection offered by spironolactone.

Gas signaling molecule hydrogen sulfide attenuates doxorubicin-induced dilated cardiomyopathy.

Increasing evidence has revealed that hydrogen sulfide (H2S) has beneficial effects in the treatment of various cardiovascular diseases. However, whether H2S can attenuate the development of dilated cardiomyopathy (DCM) remains unclear. In this study, we generated a rat model of DCM induced by doxorubicin and investigated the protective effects of H2S against DCM. Cardiac structure and function were analyzed by two-dimensional echocardiography. Oxidative stress was evaluated by measuring malondialdehyde, superoxide dismutase, glutathione peroxidase and reactive oxygen species. Cardiomyocyte apoptosis was assessed by flow cytometry following Annexin V/PI staining. Our results showed that exogenous administration of H2S could improve left ventricular structure and function in DCM rats. H2S was found to suppress doxorubicin-induced oxidative stress by activating the Nrf2 pathway and upregulating the expression of antioxidant proteins NQO1 and GCLM. Moreover, H2S was also found to inhibit doxorubicin-induced cardiomyocyte apoptosis by activating the PI3K/Akt signaling pathway. In conclusion, our study demonstrates that H2S protects against doxorubicin-induced DCM via attenuation of oxidative stress and apoptosis.

Role of blocking ADAM10 hydrolysis site on N-cadherin by single-chain antibody in ventricular remodeling.

The present study aimed to investigate the roles of the hydrolytic process of N-cadherin by A disintegrin and metalloproteases 10 (ADAM10) in sustaining myocardial structure and integrity, and discuss the mechanisms of ventricular remodeling in dilated cardiomyopathy (DCM). Single chain variable fragment antibody (ScFv) with the ability to specifically block the ADAM10 hydrolysis site of N-cadherin was designed and constructed. Western blot analysis and flow cytometry were used to detect the expression of N-cadherin and its C-terminal fragment 1 (CTF1) on cardiomyocytes, and cells were also subjected to a cell adhesion assay. Furthermore, in a rat model of dilated cardiomyopathy (DCM), the effects of intracardiac injection of the recombinant adenovirus on cardiac structure and contractile function were observed by hematoxylin and eosin staining and color Doppler echocardiography. The recombinant ScFv-expressing adenoviral plasmid with the ability to block the ADAM10 hydrolysis site on N-cadherin was successfully constructed and efficiently transfected into H9C2 cells. After transfection, N-cadherin protein expression was significantly increased, CTF1 protein was significantly decreased and the adhesion capability of myocardial cells was significantly improved. In the in vivo experiment, N-cadherin expression was significantly increased in the treatment group compared with that in the model group, and the structure and function of the heart were significantly improved. In conclusion, blocking of the ADAM10 hydrolysis site on N-cadherin by ScFv increased N-cadherin expression and improved ventricular remodeling. The present study provided experimental evidence for a novel approach for the treatment and prevention of DCM.

Intramyocardial bone marrow mononuclear cells versus bone marrow–derived and adipose mesenchymal cells in a rat model of dilated cardiomyopathy

BackgroundEffects of cell therapy on dilated cardiomyopathy (DCM) have been investigated in pre-clinical models using distinct cellular types in each study. A single study that compares the effectiveness of different cells is lacking. MethodsWe have compared the effects of intramyocardial injection (IMI) of bone marrow (BM)–derived mononuclear cells (MNCs), BM and adipose tissue (AT) mesenchymal stromal cells (BM-MSCs and AT-MSCs) on heart function, histological changes and myocardial ultrastructure in a rat model of DCM. Isogenic Wistar rats were used to isolate the different cell types and to induce DCM by autoimmune myocarditis. Animals were randomly assigned to receive BM-MNCs, BM-MSCs, AT-MSCs or placebo at day 42 by IMI. Serial echocardiography was used to assess cardiac function and hearts obtained after sacrifice at day 70, were used for histological and ultrastructural analysis. Serum levels of type B-natriuretic peptide (BNP) and vascular endothelial growth-factor (VEGF) were determined at different time points. ResultsBM-MSC treatment induced significant improvement in ejection fraction (EF), fractional shortening (FS), left ventricular systolic diameter (LVESD) and systolic volume (LVESV). In contrast, changes in echocardiographic parameters with respect to pre-treatment values in animals receiving placebo, AT-MSCs or BM-MNCs were not statistically significant. EF and FS in animals receiving AT-MSCs were superior to those receiving placebo. BM-MSC transplantation induced also improvement in cardiac fibers organization and capillary density, fibrotic tissue reduction, increase in final VEGF concentration and BNP decrease. DiscussionIMI of BM or AT-MSCs improves LV function and induces more angiogenesis processes than BM-MNCs. In addition, BM-MSCs showed more anti-fibrotic effects and more ability to reorganize myocardial tissue compared with the other cell types.

The long non-coding RNA H19 promotes cardiomyocyte apoptosis in dilated cardiomyopathy.

In the previous study, we generated a rat model of dilated cardiomyopathy (DCM) induced by adriamycin and found that the expression of lncRNA H19 was significantly upregulated in myocardial tissue. The present study was aimed to investigate the potential role of H19 in the pathogenesis of adriamycin-induced DCM. H19 knockdown in the myocardium of DCM rats attenuated cardiomyocyte apoptosis and improved left ventricular structure and function. Adriamycin treatment was associated with elevated H19 and miR-675 expression and increased apoptosis in neonatal cardiomyocytes. Enforced expression of miR-675 was found to induce apoptosis in cardiomyocytes with adriamycin treatment and H19-siRNA transfection. The 3′-untranslated region of PA2G4 was cloned downstream of a luciferase reporter construct and cotransfected into HEK293 cells with miR-675 mimic. The results of luciferase assay showed that PA2G4 was a direct target of miR-675. The expression of PA2G4 was reduced in cardiomyocytes transfected with miR-675 mimic. Moreover, H19 knockdown was found to increase PA2G4 expression and suppress apoptosis in cardiomyocytes exposed to adriamycin. In conclusion, our study suggests that H19/miR-675 axis is involved in the promotion of cardiomyocyte apoptosis by targeting PA2G4, which may provide a new therapeutic strategy for the treatment of adriamycin-induced DCM.

Developing a rat model of dilated cardiomyopathy with improved survival.

To compare the continuous infusion and intermittent bolus injection administration protocols of doxorubicin (Dox) under the same cumulative dose (12 mg/kg), and establish a rat dilated cardiomyopathy model with improved survival, a total of 150 Sprague-Dawley (SD) rats were divided into three groups: a control group, administered with normal saline; a Dox 1 group, administration twice a week at 1 mg/kg; a Dox 2, administration once a week at 2 mg/kg. Mortality rates in the Dox 1 and Dox 2 groups were 22% and 48%, respectively (P<0.05). As shown by echocardiography, both Dox groups exhibited significant chamber dilatation and reduced cardiac function (all P<0.05 vs. control). Plasma brain natriuretic peptide and C-reactive protein concentrations were significantly increased (P<0.05) with both Dox regimens. The concentrations of Caspase-3 in myocardial tissues of rats significantly increased in both doxorubicin regimens. Myocardial metabolism imaging by histology and 18F-fluoro-deoxyglucose-positron emission tomography (18FDG-PET) both revealed decreased myocardial viability and necrosis, and even interstitial fibrosis, in left ventricles (LVs) in both Dox groups. Serum creatinine and aspartate aminotransferase concentrations were significantly higher in the Dox 2 model than in the Dox 1 model. Doxorubicin given at both regimens induced dilated cardiomyopathy, while its administration at lower doses with more frequent infusions reduced the mortality rate.

Comparative effects of torasemide and furosemide on gap junction proteins and cardiac fibrosis in a rat model of dilated cardiomyopathy.

Cardiac fibrosis is the major hallmark of adverse cardiac remodeling in chronic heart failure (CHF) and its therapeutic targeting might help against cardiac dysfunction during chronic conditions. Diuretic agents are potentially useful in these cases, but their effects on the cardiac fibrosis pathogenesis are yet to be identified. This study was designed to identify and compare the effects of diuretic drugs torasemide and furosemide on cardiac fibrosis in a rat model of dilated cardiomyopathy induced by porcine cardiac myosin mediated experimental autoimmune myocarditis. Gap junction proteins, connexin-43 and N-cadherin, expressions were downregulated in the hearts of CHF rats, while torasemide treatment has upregulated their expression. Western blotting and immunohistochemical analysis for various cardiac fibrosis related proteins as well as histopathological studies have shown that both drugs have potential anti-fibrotic effects. Among them, torasemide has superior efficacy in offering protection against adverse cardiac remodeling in the selected rat model of dilated cardiomyopathy. In conclusion, torasemide treatment has potential anti-fibrotic effect in the hearts of CHF rats, possibly via improving the gap junction proteins expression and thereby improving the cell-cell interaction in the heart. © 2016 BioFactors, 43(2):187-194, 2017.

GW26-e2946 Increased expression of mitochondrial calreticulin in a rat model of dilated cardiomyopathy

GW26-e2946 Increased expression of mitochondrial calreticulin in a rat model of dilated cardiomyopathy

Involvement of caspases and their upstream regulators in myocardial apoptosis in a rat model of selenium deficiency-induced dilated cardiomyopathy

Keshan disease is an endemic dilated cardiomyopathy (DCM) which is closely related with selenium-deficient diet in China. In the previous study, we reported that the low selenium status plays a pivotal role in the myocardial apoptosis in the DCM rats, however, the underlying mechanism remains unclear. The present study aimed to determine whether the intrinsic, extrinsic pathways and the upstream regulators were involved in the myocardial apoptosis of selenium deficiency-induced DCM rats. Therefore, the rat model of endemic DCM was induced by a selenium-deficient diet for 12 weeks. Accompanied with significant dilation and impaired systolic function of left ventricle, an enhanced myocardial apoptosis was detected by TUNEL assay. Western blot analysis showed remarkably increased protein levels of cleaved caspase-3, caspase-8, caspase-9, and cytosolic cytochrome c released from the mitochondria. In addition, the immunoreactivities of p53 and Bax were significantly up-regulated, while the anti-apoptotic Bcl-2 family members Bcl-2 and Bcl-XL were down-regulated. Furthermore, appropriate selenium supplement for another 4 weeks could partially reverse all the above changes. In conclusion, the intrinsic, extrinsic pathways and the upstream regulators such as p53, Bax, Bcl-2, and Bcl-XL were all involved in selenium deficiency-induced myocardial apoptosis.

Beneficial effects of intramyocardial mesenchymal stem cells and VEGF165 plasmid injection in rats with furazolidone induced dilated cardiomyopathy.

To explore the impact of myocardial injection of mesenchymal stem cells (MSCs) and specific recombinant human VEGF165 (hVEGF165) plasmid on collagen remodelling in rats with furazolidone induced dilated cardiomyopathy (DCM). DCM was induced by furazolidone (0.3 mg/bodyweight (g)/day per gavage for 8 weeks). Rats were then divided into four groups: (i) PBS group (n = 18): rats received equal volume myocardial PBS injection; (ii) MSCs group (n = 17): 100 μl culture medium containing 105 MSCs were injected into four sites of left ventricular free wall (25 μl per site); (iii) GENE group (n = 18): pCMVen-MLC2v-EGFP-VEGF165 plasmid [5 × 109 pfu (0.2 ml)] were injected into four sites of left ventricular free wall (0.05 ml per site)] and (iv) MSCs+GENE group (n = 17): rats received both myocardial MSCs and pCMVen-MLC2v-EGFP-VEGF165 plasmid injections. After 4 weeks, cardiac function was evaluated by echocardiography. Myocardial mRNA expressions of type I, type III collagen and transforming growth factor (TGF)-β1 were detected by RT-PCR. The protein expression of hVEGF165 was determined by Western blot. Myocardial protein expression of hVEGF165 was demonstrated in GENE and MSCs+GENE groups. Cardiac function was improved in MSCs, GENE and MSCs+GENE groups. Collagen volume fraction was significantly reduced and myocardial TGF-β1 mRNA expression significantly down-regulated in both GENE and MSCs+GENE groups, collagen type I/III ratio reduction was more significant in MSCs+GENE group than in MSCs or GENE group. Myocardial MSCs and hVEGF165 plasmid injection improves cardiac function possibly through down-regulating myocardial TGF-β1 expression and reducing the type I/III collagen ratio in this DCM rat model.

Suppression of PKCε-mediated mitochondrial connexin 43 phosphorylation at serine 368 is involved in myocardial mitochondrial dysfunction in a rat model of dilated cardiomyopathy.

Mitochondrial connexin43(Cx43) is important in cardioprotection by ischemic preconditioning; however, whether mitochondrial Cx43 is involved in mitochondrial dysfunction in the pathogenesis of dilated cardiomyopathy (DCM) remains to be elucidated. The present study was performed to investigate the changes in expression and the phosphorylation state of mitochondrial Cx43 in a rat model of DCM, and to determine whether the altered phosphorylation state of mitochondrial Cx43 was involved in mitochondrial dysfunction. A rat model of DCM was generated by daily oral administration of furazolidone (FZD) for 30weeks. Reverse transcription polymerase chain reaction and western blot analysis revealed a decrease in the overall expression of Cx43, accompanied by reduced levels of serine 368‑phosphorylated‑Cx43 immunoreactivity in the myocardium and myocardial mitochondria. In addition, the mitochondrial membrane potential and the activities of cytochrome c oxidase, succinate dehydrogenase and protein kinase C(PKC)ε were all significantly reduced compared with those of the control group. Phorbol‑12‑myristate‑13‑acetate (PMA), a specific PKC activator, partially reversed the FZD‑induced mitochondrial Cx43 dephosphorylation at serine368 and mitochondrial dysfunction in the cardiomyocytes. However, pretreatment with 18β‑glycerrhetinic acid, a connexin channel inhibitor, eliminated the mitochondrial protective effect of PMA in the cardiomyocytes sparsely plated without cell to cell contact. These results suggested that dephosphorylation of mitochondrial Cx43 at serine368, due to the suppression of PKCε activity, may be a novel mechanism for mitochondrial dysfunction in the pathogenesis of DCM.

H3K9 histone methyltransferase G9a ameliorates dilated cardiomyopathy via the downregulation of cell adhesion molecules.

Dilated cardiomyopathy (DCM) is one of the leading causes of mortality; however, the underlying molecular mechanisms of DCM remain to be elucidated. H3K9 histone methyltransferase G9a has been previously characterized, although its functions in DCM are not yet understood. Cell adhesion molecules (CAM) are highly expressed in diseased human hearts and were thought to contribute to chronic degeneration in cardiac incompetence; however, it has been suggested that G9a may suppress the effects of CAM. The aim of the present study was to investigate whether G9a decreased the risk of DCM via regulation of CAM expression. A rat model of DCM was induced using furazolidone (FZ) treatment and numerous parameters were examined. G9a RNA interference (RNAi) was applied to primary neonatal cardiomyocytes (PNCs). Reverse transcription quantitative polymerase chain reaction and western blot analyses were used to examine the expression levels of G9a in the DCM model and PNCs. The growth rate of PNCs was evaluated following G9a RNAi and FZ treatment. The results confirmed that the expression levels of G9a were significantly decreased in the DCM model compared with those in the control group (P<0.01). Conversely, CAM expression levels were significantly increased in the DCM model compared with those in the control group (P<0.01). In PNCs, the expression of CAM was upregulated following G9a silencing using RNAi. Following three‑day culture, the growth rate of PNCs was inhibited by 70 and 35% following FZ treatment and G9a RNAi, respectively. In conclusion, G9a ameliorated DCM via downregulation of CAMs, therefore indicating its potential for use in the treatment of DCM.

GW25-e0744 Suppression of PKCε-medicated mitochondrial connexin 43 phosphorylation at serine 368 is involved in mitochondrial dysfunction in a rat model of dilated cardiomyopathy

GW25-e0744 Suppression of PKCε-medicated mitochondrial connexin 43 phosphorylation at serine 368 is involved in mitochondrial dysfunction in a rat model of dilated cardiomyopathy

Novel distribution of calreticulin to cardiomyocyte mitochondria and its increase in a rat model of dilated cardiomyopathy

BackgroundCalreticulin (CRT), a Ca2+-binding chaperone of the endoplasmic reticulum, can also be found in several other locations including the cytosol, nucleus, secretory granules, the outer side of the plasma membrane, and the extracellular matrix. Whether CRT is localized at mitochondria of cardiomyocytes and whether such localization is affected under DCM are still unclear. Methods and resultsThe DCM model was generated in rats by the daily oral administration of furazolidone for thirty weeks. Echocardiographic and hemodynamic studies demonstrated enlarged left ventricular dimensions and reduced systolic and diastolic function in DCM rats. Immuno-electron microscopy and Western blot showed that CRT was present in cardiomyocyte mitochondria and the mitochondrial content of CRT was increased in DCM hearts (P<0.05). Morphometric analysis showed notable myocardial apoptosis and mitochondrial swelling with fractured or dissolved cristae in the DCM hearts. Compared with the control group, the mitochondrial membrane potential level of the freshly isolated cardiac mitochondria and the enzyme activities of cytochrome c oxidase and succinate dehydrogenase in the model group were significantly decreased (P<0.05), and the myocardial apoptosis index and the caspase activities of caspase-9 and caspase-3 were significantly increased (P<0.05). Pearson linear correlation analysis showed that the mitochondrial content of CRT had negative correlations with the mitochondrial function, and a positive correlation with myocardial apoptosis index (P<0.001). The protein expression level of cytochrome c and the phosphorylation activity of STAT3 in the mitochondrial fraction were significantly decreased in the model group compared with the control group (P<0.05). ConclusionsThese data demonstrate that CRT is localized at cardiomyocyte mitochondria and its mitochondrial content is increased in DCM hearts.