Effect of bFGF on promoting angiogenesis in infarct area and improving myocardial fibrosis in mouse myocardial infarction model

AIM: To investigate the protective effect of basic fibroblast growth factor (bFGF) on the heart of mice with myocardial infarction and its mechanism. METHODS: The model of myocardial infarction was established by the ligation of left anterior descending artery of C57/B6 mice (8~12 weeks old) after lateral thoracotomy. The mice were divided into sham operation group, myocardial infarction group and bFGF administration group. bFGF at 0.5 μg was intraperitoneally injected on alternate days after myocardial infarction for 7 d. Cardiac Doppler ultrasonography was used to detect cardiac function after myocardial infarction for 28 d, and left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left ventricular ejection fraction and left ventricular shortening fraction (LVFS) were used to evaluate cardiac function. After myocardial infarction for 28 d, the mice were sacrificed and the hearts were collected for preparing pathological sections. The degrees of myocardial fibrosis and angiogenesis in the myocardial infarction area were observed. Western blot was used to detect the indicators of angiogenesis. RESULTS: The results of Masson staining showed that bFGF administration significantly reduced myocardial fibrosis at 28 d after myocardial infarction. Cardiac ultrasound data showed that cardiac functions in myocardial infarction group were poorer than those in sham group, and bFGF administration significantly improved cardiac functions. Immunofluorescence staining showed that neovascularization in myocardial infarction area of bFGF administration group was more than that in myocardial infarction group. The results of Western blot showed that bFGF activated AKT/HIF-1α/VEGF signaling pathway. CONCLUSION: Intraperitoneal injection of bFGF reduces myocardial fibrosis and improves cardiac function in myocardial infarction mice. bFGF may promote angiogenesis by activating AKT/HIF-1α/VEGF signaling pathway.     

Effect of mesenchymal stem cells transfected with human heme oxygenase-1(HO-1)gene on myocardial apoptosis and angiogenesis

AIM: To investigate the effects of mesenchymal stem cells(MSCs)transfected with human heme oxygenase-1(HO-1)gene on myocardial apoptosis and angiogenesis. METHODS: MSCs were acquired from the bone marrow of adult rats. The cells were isolated, purified, cultured, and transfected with Adv-HO-1 in vitro before transplantation. At 1 h after left coronary artery ligation, Adv-HO-1-MSCs or MSCs were directly injected into the border of cardiac infarction in rats. Western blotting analysis was used to measure HO-1, and Bax protein expression in the border of cardiac infarction. ELISA was used to measure the expressions of VEGF and bFGF in the border of cardiac infarction. At 4 weeks after transplantation, the heart functions in survival rats were examined by the Buxco system. The rats were killed, then the myocardial infarct size was measured with Masson’s trichrome, and the expression of CD34 in myocardial infarction area was detected by immunohistochemical method. RESULTS: HO-1-MSCs exhibited increased HO-1 expression. The expression of HO-1, VEGF and bFGF in the border of cardiac infarction in the rats treated with HO-1-MSCs were higher than those in the rats treated with MSCs and PBS(P<0.01). However, the expression of apoptotic protein Bax was significantly lower than that in the rats treated with MSCs and PBS(P<0.01). The number of capillary vessels in the border of cardiac infarction in the rats treated with HO-1-MSCs was significantly higher than that in the rats treated with MSCs and PBS. The cardiac function in the rats treated with HO-1-MSCs was better than that in the rats treated with MSCs and PBS(P<0.01). CONCLUSION: The favorable effect on heart function appears to be a combined outcome of HO-1 and paracrine factors released by MSCs.     

Effect of Shenshuguanxin granula on coronary circulation in rats with myocardial infarction

AIM：To explore the effect of traditional Chinese medicine Shenshuguanxin granula on coronary circulation in a rat model of myocardial infarction (MI). METHODS：SD rats (n=50, SPF grade) were randomly divided into 5 groups (n=10):sham group, MI group, and high-dose, middle-dose and low-dose Shenshuguanxin granula treatment groups. The rat MI model was established by ligation of the coronary artery. The cardiac markers, small and medium-sized blood vessels ［microvessel count (MVC) value］ in the infarct zone, and platelet endothelial cell adhesion mo-lecule 1 (PECAM-1) and vascular endothelial growth factor (VEGF) expression in the infarct border zone were measured. RESULTS：After 4 weeks of coronary artery ligation, the significant increases in MVC in the infarct zone, and the expression of PECAM-1 and VEGF in the infarct border zone were detected compared with sham group (P<0.05). The differences of cardiac markers between MI group and other groups were insignificant (P>0.05). CONCLUSION:Shenshuguanxin granula improves coronary circulation in the rats with myocardial infarction by increasing the expression of PECAM-1 and VEGF, and promoting small and medium-sized angiogenesis.     

Adrenomedullin gene transfection enhances the therapeutic effects of transplantation of bone marrow mesenchymal stem cells on cardiac function and ventricle remodeling in acute myocardial infarction rats

AIM: To investigate adrenomedullin gene transfection enhances the therapeutic effects of homogeneous transplantation of bone marrow mesenchymal stem cells (MSCs) on cardiac function and ventricle remodeling in acute myocardial infarction rats. METHODS: MSCs were isolated and expanded using the preplating method. The infection efficiency of adenovirus vector to MSCs was tested by X-gal staining. Ad-ADM expression in MSCs and its secretion in culture medium were measured by ELISA. The left anterior descending branch of rats was ligated to establish a myocardial infarction model. The MSCs were labeled by DAPI, and were directly implanted into the acute infarct site via focal injection. Four weeks later, cardiac function was evaluated using physiological recorder. Hearts were harvested and sliced to be analyzed by immunohistochemistry (factor Ⅷ and ADM) and the DAPI-labeled cells were identified. Sirius red staining was used to identify interstitial collagen on slides. Analysis of collagen type I and III was performed using a polarized filter on sections stained for collagen with Sirius red, and the ratio of collagen type I and III were detected. RESULTS: With X-gal staining, MSCs were effectively transfected by adenovirus in vitro. The transfection efficiency showed the dose-effect relationship with multiplicities of infection (MOI). When MOI was 150, the infection efficiency was 95.4%. The expression of ADM was traced in culture medium and expressed in the time-dependent manner. A maximum production of ADM was observed at 7 d after infection ［(26.53±1.42) ng/L vs (1.34±0.08) ng/L, P<0.05］, and ADM secretion reduced to normal level at 15 d ［(2.20±1.44) ng/L vs (1.52±0.33) ng/L, P>0.05］. DAPI-labeled MSCs transplantation was found in the hearts of the recipients. Immunohistochemical studies demonstrated that intense immunostaining for ADM was higher in Ad-ADM plus MSCs group, compared to other groups. Compared with control, MSCs transplantation significantly increased capillary density in infarct area (P<0.01). A combination of Ad-ADM trensfection and MSCs transplantation demonstrated a further increase in capillary density compared with Ad-ADM or MSCs alone. MSCs transplantation decreased the ratio of collagen type I and III, obviously improved the left ventricular functions. Furthermore the combination treatment resulted in further decrease in the ratio of collagen type I and III, and significantly improved the left ventricular functions. CONCLUSION: Ad-ADM transfection enhances the angiogenic potency of MSCs transplantation and decreases the ratio of collagen type I and III through increasing ADM expression in infarct area, thus contributes to reverse the ventricular remodeling and improves the cardiac function.     

Transplantation of bcl-2 gene-modified bone marrow mesenchymal stem cells improves cardiac function and angiogenesis in rabbit ischemic car-diac insufficiency model

AIM: To investigate the effects of transplantation of bone marrow mesenchymal stem cells (BMSCs) modified by bcl-2 gene on myocardial cell apoptosis, angiogenesis and cardiac function in the rabbit after acute myocardial infarction (MI).METHODS: The rabbit BMSCs were isolated, cultured and purified in vitro. The BMSCs were transfected with adenovirus or adenovirus-Bcl-2. The rabbit model of MI was established by ligation of left anterior descending branch. The rabbits were injected with Ad-Bcl-2-BMSCs (MI+Bcl-2-BMSCs group), Ad-BMSCs (MI+BMSCs group) and DMEM (MI group) in infarction marginal zone 2 weeks after ligation. The cardiac function was evaluated by echocardiography.The apoptosis of myocardial cells was measured by TUNEL. The mRNA expression of VEGF was detected by real-time PCR. The expression of CD31 was examined by immunohistochemical staining, and new blood capillaries were counted at 4 weeks after BMSCs transplantation. The correlation of the above values with cardiac function was analyzed.RESULTS: The cardiac function was better, the apoptotic rate was lower, the mRNA expression of VEGF and the capillary density were higher in both MI+Bcl-2-BMSCs group and the MI+BMSCs group than those in MI group, and those in MI+Bcl-2-BMSCs group increased more obviously.The left ventricular ejection fraction (LVEF) had a negative correlation with the myocardial cell apoptosis rate. A positive correlation with the mRNA expression level of VEGF and the capillary density was also observed.CONCLUSION: The transplantation of BMSCs modified by bcl-2 gene significantly reduces the myocardial cell apoptosis, promotes angiogenesis, improves heart function of the rabbits with MI.     

Autologus marrow stromal cell transplantation improves rabbit cardiac performance after myocardiac infarction

AIM: We tested the hypothesis that marrow stromal cells (MSCs), when implanted into self-myocardium, can undergo milieu-dependent differentiation, express cardiomyogenic phenotypes and enhance angiogenesis and cardiac function of ischemic hearts in vivo. METHODS: In order to achieve a safe and persistent effect, we explored the potential of autologous MSCs transplantation. One week after myocardial infarction induced by occlusion of left anterior descending artery, autologous MSCs labeled with BrdU (bromodeoxyuridine) in vitro was administered intramyocardially into the infarct area of the same donor rabbits. RESULTS: By 1 months, transplanted MSCs demonstrated to be myogenic differentiation with the expression of α-sarcomeric actin (5C5). MSCs implantation significantly increased vascular density in the infarct zone and resulted in markedly improved the left ventricular contractility. CONCLUSION: The finding indicates that autologous MSCs transplantation may represent a promising therapeutic strategy with free of ethical concerns and immune rejection.     

Effect of livin-modified BM-MSCs transplantation on cardiac function following acute myocardial infarction in a rat model

AIM: To study the effect of livin gene-modified bone marrow mesenchymal stem cells(BM-MSCs) transplantation on the cardiac function following acute myocardial infarction in a rat model and the expression of livin, caspase-3, caspase-7 and caspase-9 in the livin gene-modified BM-MSCs. METHODS: The MSCs were obtained by the whole bone marrow culture method, and the apoptosis of the MSCs after infection with adenovirus vector carrying enhanced green fluorescent protein(EGFP) gene and livin recombinant vector(rAd-livin) were detected by flow cytometry. The expression of livin, caspase-3, caspase-7 and caspase-9 was detected by Western blot. After permanent left anterior descending artery occlusion, the rats were randomized to receive intramyocardial injection of DMEM without cells(vehicle group), or containing MSCs(MSCs group), MSCs(EGFP)(rAd-control/MSCs group) or MSCs(livin)(rAd-livin/MSCs group). Left ventricular systolic pressure(LVSP), left ventricular end-diastolic pressure(LVEDP), the maximum increased rate of left ventricular pressure(-dp/dt_max) and the maximum decline rate of left ventricular pressure(+dp/dt_max) were recorded for evaluating the cardiac functions. RESULTS: The apoptosis of rAd-livin/MSCs was significantly decreased as compared with MSCs and rAd-control/MSCs(P<0.05). Meanwhile, the expression of caspase-3, caspase-7 and caspase-9 was significantly downregulated as compared with the other 2 groups(P<0.05). The cardiac function in rAd-livin/MSCs group was significantly improved as compared with DMEM group, and those in the other 2 groups got the similar results, but the function in rAd-livin/MSCs group was better improved. Meanwhile, the number of surviving cells in rAd-livin/MSCs group was significantly improved as compared with the other 2 groups. CONCLUSION: The apoptosis of MSCs is decreased after rAd-livin transfection, and the expression of caspase-3, caspase-7 and caspase-9 is also significantly downregulated while the expression of livin is significantly upregulated. Transplantation of livin-modified BM-MSCs by lentiviral vector results in better prognosis for treating myocardial infarction by enhancing cell survival.     

Preliminary investigation on combining autologous marrow stromal cells transplantation with granulocyte colony stimulating factor for improvement of rabbit cardiac performance after actue myocardiac infarction

AIM: To test the hypothesis that autologous marrow stromal cells (MSCs) transplantation combined with granulocyte colony stimulating factor (G-CSF) can enhance cardiac function of ischemic hearts in vivo.METHODS: In order to achieve a safe and persistent effect,we explored the potential of autologous MSCs transplantation.Acute myocardial infarction induced by occlusion of left anterior descending artery,autologous MSCs labeled with BrdU bromodeoxyuridine in vitro were administered intramyocardially into the infarct area of the same donor rabbits and G-CSF was administrated by subcutaneous injection.Four weeks later,the transplanted labeled MSCs were detected by laser scanning confocal microscopy and the cardiac functions were examined by echocardiogram and multichannel physiologic recorder.Myocardial infarct size was measured from mid-transverse sections stained with Massons trichrome.RESULTS: After 4 weeks,transplanted MSCs were demonstrated myogenic differentiation with the expression of α-sarcomeric actin and connexin 43 located in intercalated disk.MSCs combined with G-CSF transplantation improved the left ventricular contractility and reduced myocardial infarct size markedly compared to that without G-CSF tratment.CONCLUSION: Our finding indicates that autologous MSCs combined with G-CSF transplantation may represent a promising therapeutic strategy on ischemic heart disease.     

Transplantation of exogenous mesenchymal stem cells treats post-infarction ventricular remodeling in rats

AIM: This study was performed to investigate the feasibility and efficiency of exogenous mesenchymal stem cells (MSCs) transplantation on post-infarction ventricular remodeling and heart function in rats and compare the effects between adult rat MSCs and neonate rat MSCs transplantation. METHODS: 1-2 hours after left coronary artery ligation, MSCs cultured in ex vivo, marked with BrdU, were injected directly into the border of infarcts in exogenous rats. 6 weeks after transplantation, rat heart function, ventricular remodeling and pathological results were measured. RESULTS: MSCs transplantation decreased LV end-diastolic diameter and end-systolic diameter, limited LV chamber dilatation and reduced collagen content significantly. The numbers of blood vessels and cardiomyocytes were increased. BrdU-labelled MSCs with oval nucleus were widely distributed. There were no significant difference between adult rat MSCs and neonate rat MSCs transplanted groups. CONCLUSION: MSCs can survive and home in exogenous host infarct hearts without addition of any immunosuppressant. MSCs transplantation has benificial effects on remodeling processes and contributes to improvement of cardiac function, which may be related with the reduction of the amount of the collagen, promotion of myogenesis and angiogenesis.     

Promoting angiogenesis of protein kinase D1 in vitro and in vivo

AIM: To explore the effect of protein kinase D1 (PKD1) on promoting angiogenesis in vitro and in vivo, and to furnish a new idea on targeting PKD1 for the treatment of ischemic heart disease such as myocardial infarction. METHODS: The culture, isolation and identification of endothelial progenitor cells (EPCs) were performed in vitro. The effects of PKD1 and its specific blocking agent CID755673 on expression levels of vascular endothelial growth factor (VEGF) and kinase insert domain receptor (KDR) in EPCs were determined. The rat model of myocardial infarction was established, the intervention effects of PKD1 and CID755673 on morphology, changes of microvessels and endothelial cells, and the expression of VEGF and KDR in the impaired myocardial tissue were analyzed. RESULTS: PKD1 significantly upregulated the expression of VEGF and KDR in EPCs in vitro. Meanwhile, the structure of myocardial tissue was more regular and clear, the cytomembrane of endothelial cells were more smooth and integrity, the pericytes were visible, and the expression of VEGF and KDR was significantly increased in PKD1 treatment group in vivo.CONCLUSION: PKD1 has the ability of angiogenesis obviously, which might be mediated by VEGF.     

Correlation between myocardial interstitial collagen remodeling and changes in hemodynamics in rats with myocardial infarction

AIM: To study the relationship between cardiac extracellular matrix remodeling and cardiac function after myocardial infarction. METHODS: We observed sequential changes in collagen contents and collagen Ⅰ/Ⅲ ratios in infarct zone (IZ) and non-infarct zone (NIZ) and their relationship to the parameters of left ventricular systolic and diastolic function in the rat model of myocardial infarction induced by ligation of left main coronary artery. RESULTS: Collagen conteants in IZ and NIZ after 3d of myocardial infarction were significantly higher than those in sham group at corresponding time (P<0.05, P<0.01). Collagen Ⅰ/Ⅲ ratio in IZ decreased on day 3, significantly increased after 7 d (P<0.01). Collagen Ⅰ/Ⅲ ratio in NIZ increased significantly afte14 d. Correlated analysis between collagen contents in IZ or NIZ and collagen type Ⅰ/Ⅲ ratio and maximal ascending velocity (+p'_max) or maximal descending velocity of the left ventricular pressure (-p'_max) was performed and the negative correlation between collagen contents in NIZ and +P'_max (r=-0.589, P>0.05) and -P'_max (r=-0.788, P<0.01) was found. Collagen content in IZ positively correlated to the +P'_max (r=0.70, P<0.50), but not to -P'_max (r=-0.29, P>0.05). Collagen type Ⅰ/Ⅲ ratios in NIZ correlated negatively to the +P'_max (r=-0.504, P>0.05) and -P'_max (r=-0.545, P>0.05), but there were no relationship between collagen type Ⅰ/Ⅲ ratios in IZ and +P'_max or -P'_max in IZ. CONCLUSION: Collagen deposition in IZ after myocardial infarction was of benefit to improvement of systolic function. Collagen deposition in NIZ was harmful to systolic and diastolic function.     

Astragaloside IV promotes angiogenesis in rats with myocardial infarction via PKD1-HDAC5-VEGF pathway

AIM: To investigate the angiogenic effect and mechanisms of astragaloside IV (AS-IV) in rats with myocardial infarction via protein kinase D1 (PKD1)-histone deacetylase 5 (HDAC5)-vascular endothelial growth factor (VEGF) signaling pathway. METHODS: The classic model of myocardial infarction by ligation of the left anterior descending coronary artery was replicated, and the rats were randomly divided into model group, AS-IV group, and AS-IV+CID755673 (PKD1 inhibitor) group. The sham operation control group and DMSO control group were also set up. All the rats were given intravenous injection via caudal vein. The rats were sacrificed 4 weeks later, and segmental heart samples were used for HE staining and Masson staining. The expression of PKD1, HDAC5 and VEGF was analyzed by immunohistochemistry, RT-PCR and and Western blot. RESULTS: Compared with sham operation group and DMSO group, the myocardium in model group showed disordered arrangement, accompanied with necrotic myocardial cells and obvious fibrosis tissue. After treatment with AS-IV, the morphological changes of myocardium were obviously improved, and the number of new blood vessels increased significantly. However, after treatment with AS-IV+CID755673, the myocardial tissues of the rats became disordered again, with increased necrotic cells and some closed vessels. The mRNA and protein expression of PKD1, HDAC5 and VEGF in myocardial tissue in model group was significantly lower than that in sham operation and DMSO groups (P<0.05). The expression in AS-IV group was significantly higher than that in model group (P<0.01), while that in AS-IV+ CID755673 group was significantly lower than that in AS-IV group (P<0.05). CONCLUSION: AS-IV promotes the angiogenesis of myocardial tissues in the rats after myocardial infarction partly by regulating the PKD1-HDAC5-VEGF signaling pathway.     

Salvia extract promotes angiogenesis of myocardium in rats with myocardial infarction

AIM: To determine the effect of salvia extract on angiogenesis of the myocardium in the rats with myocardial infarction (MI) and to analyze its possible mechanism. METHODS: Left coronary artery of Sprague-Dawley rats was ligated to establish a MI model. The rats were randomly divided into MI model group, 3 different dose groups of salvia (10, 20 and 40 mg·kg^-1·d^-1), and sham operation group. Each group consisted of 8 rats. The rats in all treatment groups were orally administered with the salvia extract, and the rats in MI group and sham operation group were fed with the same volume of saline. The rats were sacrificed 4 weeks later. The hemodynamic changes of the rats were determined, and the segmental heart samples were used for morphological observation by hematoxylin and eosin staining, Masson staining, or electron microscopic analysis. The expression of vascular endothelial growth factor (VEGF) and cluster of differentiation 34 (CD34) was analyzed according to immunohistochemistry. RESULTS: Compared with sham operation group, the morphological changes of the myocardium in MI group were disordered, part of myocardial cell outline disappeared, and obvious fibrosis in the necrosis myocardial tissue and fuzzy or disappearing microvascular ultrastructure were also observed. Compared with MI group, the number of new microvessels in all the treatment groups increased obviously, and the morphological changes of the endothelial cells were relatively complete according to electron microscopy. Compared with sham operation group, the protein expression of VEGF and CD34 in the cytoplasm of the myocardial tissues in MI group increased only a little. Compared with MI group, the protein expression of VEGF and CD34 in the cytoplasm of the myocardial tissues in all treatment groups increased significantly (P<0.01). CONCLUSION: Salvia extract obviously promotes angiogenesis of the myocardial tissues in the rats after myocardial infarction.     

Effects of pretreatment with captopril on the infarct size and myocardial cell apoptosis in experimental rabbits

AIM:To investigate the effects of pretreatment of captopril on the infarct size and myocardial cell apoptosis in rabbits. METHODS:Rabbits were randomly divided into sham-operated control group (SO), acute infarct group (AI) and captopril pretreatment group (CP). The rabbits of CP group were treated with captopril (25 mg·kg^-1.d^-1) for 1 week before harvest. The left circumflex branch of coronary (LCX) was ligated to develop acute ischemic model. The systolic and diastolic function of left ventricle(LV) was measured before and at 15, 30, 60 min after ligating LCX, and the blood viscosity and hematocrit before and at 60 min after ligating LCX were measured also. 6 hours later LCX ligation, the hearts were harvested for determining the infarction size, which was expressed as the ratio of infarct area to the total ischemic area, and evaluating apoptosis index expressed as the percentage of myocardial cells with TUNEL positive staining. RESULTS:1.Compared with AI group, captopril pretreatment significantly reduced the infarction size (16.60%±0.94% vs 36.24%±1.94%, P＜0.05), and improved the LV function and viscosity of blood. 2. Apoptosis of myocardial cell was found in the myocardium surrounding to the infarction area, however, the apoptosis index of CP group was significantly lower than that of AI group (26.30%±0.71% vs 42.44%±2.32%,P＜0.05).CONCLUSION:Apoptosis of myocardial cell exists in the area surrounding the infarction. Captopril pretreatment can reduce infarction size and myocardial apoptosis index, and improve the LV function as well as blood viscosity in this acute ischemic model.     

Expression of endostatin in ischemic myocardium of myocardial infarction rats

AIM: To study the expression of endostatin in ischemic myocardium of myocardial infarction (MI) rats in various periods and the correlation with VEGF expression and microvascular density (MVD).METHODS: Thirty-two male Sprague-Dawley rats after myocardial infarction were randomly divided into 7, 14, 21 and 28 days group.The sham group was normal control group (eight rats in each group).The expression of endostatin, VEGF and MVD in ischemic myocardium were observed by immunohistochemistry.RESULTS: The expression of endostatin significantly increased in the ischemic myocardium after MI, peaked at 7 days, then gradually decreased at 14, 21 and 28 days.The endostatin level at 28 days was the same as the shams.The changing trends of expression of endostatin in ischemic myocardium after MI were similar to that of VEGF and were significantly correlated with the MVD.CONCLUSION: The expression of endostatin increased in ischemic myocardium of myocardial infarction rats.The changing trends of endostatin were similar to that of VEGF and positively correlated with the MVD.These data suggest that endostatin may modulate ischemic myocardium angiogenesis after myocardial infarction.     

Prostaglandin E1 protects heart after myocardial infarction by inhibiting endoplasmic reticulum stress in rats

AIM To investigate the effect of prostaglandin E1 (PGE1) on heart after myocardial infarction (MI) in rats and its related molecular mechanism. METHODS Fifty male SD rats were divided into sham group, model group and model+PGE1 group. The MI rat model was established by ligation of left anterior descending coronary artery. Cardiac function in the rats was detected by echocardiogaphy. The myocardial histomorphologic changes were evaluated by HE and Masson staining. The MI area was measured by TTC staining. The cardiomyocyte death was detected by TUNEL staining. The protein levels of endoplasmic reticulum stress (ERS)-related factors glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and caspase-12, and apoptosis-related factors Bcl-2, Bax and cleaved caspase-3 were determined by immunofluorescence staining and Western blot. RESULTS Compared with sham group, the cardiac function in model group was decreased, with significant myocardial pathological changes. The MI area was enlarged, and the death of cardiomyocytes was promoted. The protein levels of GRP78, CHOP, caspase-12, Bax and cleaved caspase-3 in the myocardial tissues were significantly increased, while Bcl-2 was decreased (P<0.01). Compared with model group, the cardiac function in model+PGE1 group was significantly improved, and the myocardial pathological damage was significantlty attenuated. The MI area and myocardial cell death were significantly reduced. The protein levels of GRP78, CHOP, caspase-12, Bax and cleaved caspase-3 in the myocardial tissues were significantly decreased, while Bcl-2 was increased (P<0.01). CONCLUSION PGE1 reduces collagen deposition and inflammation, and improves cardiac function by reducing ERS level, thus protecting cardiomyocytes from MI damage.     

Expression of angiogenic factors in myocardial tissue of diabetic rats

AIM：To observe the expression of angiogenesis factors in the myocardial tissue of streptozotocin-induced diabetic rats. METHODS：The diabetic rat model was induced by intraperitoneal injection of streptozotocin. After 12 weeks, the cardiac function was measured by MPA cardiac function analysis system. The myocardial collagen volume fraction (CVF) was assessed by Masson staining. The capillary vessels was quantified as the ratio of capillary to myocyte (C/M) using CD31 immunostaining. The expression levels of vascular endothelial growth factor (VEGF), angiopoietin (Ang)-1, endostatin and Ang-2 were observed by Western blotting. RESULTS：Compared with normal control group, the left ventricular end-diastolic pressure (LVEDP) was evidently increased (P<0.01), but left ventricular pressure rise maximum rate (+dp／dtmax), left ventricular pressure decrease maximum rate (-dp／dtmax) and the ratio of capillary/myocyte (C/M) were significantly decreased (P<0.05). The CVF and the expression level of endostatin were significantly increased, whereas the expression levels of VEGF and Ang-1 evidently decreased (both P<0.05) in diabetic rats. However, no marked difference in the expression of Ang-2 between the 2 groups was observed (P>0.05). CONCLUSION：Imbalances between the angiogenic factors (VEGF and Ang-1) and anti-angiogenic factors (endostatin) may play an important role in the pathogenesis of diabetic cardiomyopathy.     

Hypoxia-inducible factor-1α is involved in myocardial angiogenesis induced by hypoxic preconditioning

AIM: To investigate the relationship between the expression of hypoxia-inducible factor-1α (HIF-1α) and myocardial angiogenesis induced by hypoxic preconditioning (HPC). METHODS: Male Sprague-Dawley rats were randomly divided into control group and hypoxic-preconditioned group. Rats in preconditioned group were subjected to hypoxic exposure (10% O2 and 90% N2) for 4 h, these rats were maintained in a normal environment respectively for 1 d, 7 d or 21 d. Then, vascular density was observed by the method of immunohistochemical staining with the antibody against factor Ⅷ-related antigen in rat myocardial tissue. Protein extracts of rat myocardial tissue were prepared for Western blotting analysis to measure the activities of extracellular signal-regulated protein kinases (ERKs) and HIF-1α. RESULTS: In hypoxic-preconditioned group, microvascular density significantly increased in myocardial tissue. The expression of ERK1/2 increased by 18.67% at 1 d after HPC. HPC induced the expression of HIF-1α, and the peak of expression was at first day after HPC. CONCLUSION: HPC promotes myocardial angiogenesis. Activation of ERKs and expression of HIF-1α might be involved in myocardial angiogenesis induced by hypoxic preconditioning.     

Effects of atorvastatin on release of endothelial microparticles and myocardial apoptosis in rats with acute myocardial infarction

AIM: To investigate the effect of atorvastatin(AT) on the release of endothelial microparticles(EMP) and myocardial apoptosis in the rats with myocardial infarction. METHODS: SD male rats(n=24) were randomly divided into 3 groups:sham operation(sham) group, myocardial infarction(MI) group and MI+AT group. The rat model of acute myocardial infarction was prepared by coronary artery ligation. At 2 h and 24 h after modeling, the peripheral blood was collected to detect creatine kinase-MB(CK-MB) and cardiac troponin T(cTnT). The circulating levels of EMP were measured by flow cytometry. The myocardial apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) assay. RESULTS: At 2 h after modeling, the level of CK-MB was significantly increased in MI group compared with sham group, and the level of EMP and the myocardial apoptotic rate were significantly increased in MI group and MI+AT group compared with sham group. At 24 h after modeling, the level of EMP was significantly increased in MI group compared with sham group. The levels of CK-MB, cTnT, EMP and the myocardial apoptotic rate were significantly decreased in MI+AT group compared with MI group. Moreover, the level of CK-MB in MI group was significantly increased at 24 h compared with that at 2 h after modeling. The levels of CK-MB, cTnT and EMP were significantly decreased in MI+AT group at 24 h compared with those at 2 h after modeling. CONCLUSION: Ator-vastatin may reduce the level of EMP and the myocardial apoptotic rate in the rats with acute myocardial infarction, indicating that atorvastatin plays a role in protecting endothelium.