Study on the potential to differentiate into myocytes of the CD34+ cells

AIM:To investigate the potential of differentiatng into myocytes of the granulocyte colony-stimulating factor(G-CSF)-mobilized CD34⁺ cells. METHODS:Three hours after intraperitoneal injecction of isoprenaline(ISO)to develop acute ischemic model,rats’bone marrow hematopoietic stem cells were mobilized to the site of myocardial infarction by G-CSF.The techniques of immunohistochemisty and HE stain were used to detect the infiltration of CD34⁺ cells and the regeneration of myocytes in the infarct zones. RESULTS:24 hours after administration of ISO, a large amount of infiltrative monocytes and regenerative myocytes which were CD34 positive expression could be found in the infarct zones of the G-CSF treatment group, while majority of the infiltrative inflammatory cells in control group were neutrophils and there was no infiltrative cells and myocytes which were CD34 positive expressio, 2 weeks after administration of ISO, there were a plenty of scar in control group, but not in the G-CSF treatment group. CONCLUSION:G-CSF-mobilized CD34⁺ cells possess the potential to differentiate into myocytes and it may be used in treating acute myocardial infarction.     

水杨酸和高温锻炼与葡萄抗热性及抗氧化的关系

 对‘京秀’葡萄(Vitis vinifera CV．Jingxiu)高温锻炼和外施水杨酸(salicylic acid，SA)都能显著提高其幼苗的抗热性。高温锻炼1 h，叶片内自由态sA含量急剧升高，其后又迅速下降。在抗热性诱导过程中(高温锻炼12 h或水杨酸喷施后6 h)，抗氧化酶系统中的过氧化物酶(POD)、超氧化物歧化酶(SOD)、谷胱甘肽还原酶(GR)、抗坏血酸过氧化物酶(APX)的活性都明显升高，但过氧化氢酶(CAT)活性下降；高温锻炼或外施SA 1 h，过氧化氢(H2o2)含量急剧升高，之后又迅速下降，可能起着一种信号分子的作用。以上结果说明内源sA可能通过提高抗氧化酶活性参与了高温锻炼过程，外施sA和高温锻炼有相似的提高抗热性机制。     

Short-term cardioprotective effects of trimetazidine on acute myocardial infarction in rats

AIM: To observe the myocardial protective effects of trimetazidine on myocardial infarction (MI) in Sprague-Dawley (SD) rats. METHODS: Ninety SD rats were randomly assigned to 3 groups (n=30 each): myocardial infarction group (MI group), MI+trimetazidine group (MT group) and sham group (S group). By permanently ligating the left anterior descending artery, the MI model was set up in the rats in MI group and MT group. Before and after setting up the MI model, normal saline was given to the rats in MI and S group by gavage. On the other hand, trimetazidine (3 mg/kg,twice per day) was given to the rats in MT group by gavage. At 8 h, 24 h and 48 h after applying trimetazidine, the serum level of cardiac troponin I (cTnI) was measured. At the 1st week, 2nd week and 4th week after treated with trimetazidine, the size of myocardial infarction, the maximum rising rate of the left ventricular systolic pressure (+dp/dt_max) and the maximum descending rate of the left ventricular diastolic pressure (-dp/dt_max) were measured. Also at the 1st week after applying trimetazidine, the cardiomyocyte apoptotic index was detected. RESULTS: Compared with MI group 2 weeks after applying trimetazidine, +dp/dt_max significantly increased in MT group , and -dp/dt_max also significantly increased in MT group . Four weeks after applying trimetazidine, +dp/dt_max significantly increased in MT group , and -dp/dt_max also significantly increased in MT group . At 8 h and 48 h after applying trimetazidine, no statistically significant difference (P＞0.05) of serum cTnI between MI group and MT group was observed. However, at 24 h after applying trimetazidine, the serum level of cTnI decreased in MT group as compared with MI group . Aditionally, trimetazidine significantly decreased the infarction size of myocardium in MT group (0.248±0.052) as compared with MI group (0.362±0.082, P<0.01). CONCLUSION: Trimetazidine has short-term cardioprotective effects on the rats with acute MI by improving myocardial systolic and diastolic functions, reducing infarct size and inhibiting apoptosis.     

Protective effects of total saponins of panax notoginseng on myocardial hypertrophy and fibrosis induced by isoproterenol in rats

AIM: To investigate the protective effects of total saponins of panax notoginseng (PNS) on myocardial hypertrophy and fibrosis induced by isoproterenol (ISO) in rats.METHODS: Myocardial hypertrophy and fibrosis model of rats were induced by injection of ISO (5 mg·kg^-1·d^-1,sc) for 7 days.From day 2,the rats were administered with PNS at dose of 25 and 50 mg·kg^-1·d^-1,ip for 14 days,the control and ISO model group were received saline injection.Then,the heart-weight (HW),left ventricular weight (LVW),the ratio of HW/BW and LVW/BW (LVI) were measured;the hydroxyproline and malondialdehyde (MDA) and angiotensin (AngII) content of left ventricle.The level of nitric oxide (NO),nitric oxide synthase (NOS),superoxide disrnutase (SOD) and glutathione peroxidase (GSH-Px) activities in left ventricle were determined by spectrophotemetry and radioimmunoassay,respectively.RESULTS: Compared with NS control group,the ratio of HW/BW,LVW/BW and the content of hydroxyproline,AngII,MDA and iNOS activity in the left ventricle were significantly increased.The cNOS,SOD,GSH-Px activities and NO content were obriously decreased in the ISO model group.After treatment with PNS,the left ventricular NO content,cNOS,SOD and GSH-Px activities were markedly higher than those in ISO model group.The content of MDA,AngII and iNOS activities and the ratio of HW/BW,LVI were significantly lower than those in ISO model group.CONCLUSION: PNS reverses the myocardial hypertrophy and fibrosis induced by isoproterenol in rats.This effect may be related to eliminating the oxygen free radicals and raising NO level.     

Cardiac protective effect of granulocyte colony-stimulating factor combined with ischemic postconditioning on acute myocardial infarction in rabbits

AIM: To investigate the protective effect of granulocyte colony-stimulating factor (G-CSF) combined with ischemic postconditioning (IP) on acute myocardial infarction (AMI). METHODS: Male New Zealand rabbits were randomly divided into 4 groups (n=15) after 30 min of left ventricular artery (LVA) occlusion: the rabbits in ischemia-reperfusion (IR) group were directly given reperfusion|the rabbits in G-CSF group were subsequently treated with G-CSF (10 μg·kg^-1·d^-1) by subcutaneous injection after direct reperfusion|the rabbits in IP group received 4 episodes of 30 s reperfusion and 30 s occlusion before total reperfusion|the rabbits in IP combined with G-CSF (IP+G-CSF) group were treated with both IP and G-CSF. Electrocardiogram (ECG) monitoring was performed during the operation. Blood was drawn to evaluate white blood cell count (WBC) and cardiac troponin I (cTnI) before operation and 7 d later. Ultrasound cardiography was performed to evaluate left ventricular remodeling and functions 4 weeks after operation. The sizes of infarcted myocardium were determined by triphenyltetrazolium chloride (TTC) staining. Apoptosis of cardiomyocytes was measured by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) staining. RESULTS: ST-segment resolutions were significantly decreased in IP group and IP+G-CSF group compared with direct reperfusion groups (P<0.05). WBC significantly increased in the groups treated with G-CSF for 1 week. The values of cTnI after operation were significantly lowered in G-CSF group, IP group and IP+G-CSF group as compared with IR group (P<0.05). Left ventricular ejection fraction, the size of infarcted myocardium and apoptosis of cardiomyocytes were better in IP group, G-CSF group and IP+G-CSF group than those in IR group. CONCLUSION: G-CSF combined with IP is a promising strategy against cardiac reperfusion injury and accelerates cardiac repair in AMI.     

Over-expression of endophilin A2 attenuates myocardial hypertrophy induced by isoprenaline

AIM:To examine the effect of endophilin A2 (EndoA2) over-expression on myocardial hypertrophy induced by isoprenaline (ISO). METHODS:Healthy male SD rats were divided into 4 groups, including sham group, Ad-EndoA2 group, ISO group and ISO+Ad-EndoA2 group. The rats in Ad-EndoA2 group and ISO+Ad-EndoA2 group were injected with Ad-EndoA2 adenovirus into the wall of the left ventricle 1 d before the administration of normal saline or ISO, while the rats in sham group and ISO group were injected with PBS. Subsequently, normal saline or ISO were subcutaneously injected into the rats for 7 consecutive days. After 7 d, small-animal echocardiography was used to detect the cardiac function. The hearts were harvested. The heart weight index, hematoxylin and eosin (HE) staining, and the expression of fetal genes were observed to identify myocardial hypertrophy. The protein expression of LC3 and P62 was detected by Western blot. RESULTS:The results of small-animal echocardiography showed that the rats in ISO group were in the compensatory period of myocardial hypertrophy compared with sham group, evidenced by increased LVAWs, LVPWs, EF and FS, and decreased LVIDs and CO (P<0.05). In addition, the results of heart weight index, HE staining and RT-qPCR showed that myocardial hypertrophy was induced by ISO successfully (P<0.05). Over-expression of EndoA2 inhibited myocardial hypertrophy induced by ISO and improved cardiac function (P<0.05). The results of Western blot showed that EndoA2 over-expression obviously reversed the decreased level of autophagy induced by ISO (P<0.05).CONCLUSION:Over-expression of EndoA2 may attenuate myocardial hypertrophy induced by ISO due to strengthening autophagy.     

Effect of atorvastatin on cardiac function and HGF/c-Met signaling pathway after acute myocardial infarction in diabetic rats

AIM: To investigate the effect of atorvastatin on myocardial apoptosis, ventricular remodeling and cardiac function after acute myocardial infarction (AMI) in diabetic rats, and to explore whether the effect is mediated by hepatocyte growth factor (HGF)/c-Met signaling pathway. METHODS: Diabetes in 70 male SD rats was induced by intraperitoneal injection of streptozotocin (STZ, 65 mg/kg). After 8 weeks, AMI was induced by the ligation of the left anterior descending coronary artery in the diabetic rats, and 32 surviving rats were divided into AMI group (n=16) and AMI＋atorvastatin group (n=16, 20 mg·kg-1·d-1) at random. The similar surgical procedure was completed in sham group (n=11) without coronary ligation. Atorvastatin was given daily by gavage from the first day after AMI. Two weeks later, the cardiac function, pathological changes of myocardial tissues, myocardial apoptosis, and the expression of HGF and c-Met were compared among groups. RESULTS: AMI significantly reduced cardiac function, increased collagen volume fraction (CVF) and myocardial apoptotic index, and up-regulated the expression of HGF and c-Met at mRNA and protein levels in AMI control group (P<0.05). The cardiac function was improved, and CVF and myocardial apoptotic index were reduced by the treatment with atorvastatin, which also up-regulated the expression of HGF and c-Met (P<0.05). CONCLUSION: Atorvastatin significantly attenuates myocardial apoptosis and cardiac remodeling, and improves cardiac function after AMI in diabetic rats by further enhancing the activation of HGF/c-Met pathway.     

Changes of cytokine and collagen in the myocardial remodeling after acute myocardial infarction in rats

AIM:To clarify the relationship between the cytokine and collagen in myocardial remodeling after acute myocardial infarction (MI) in rats. METHODS:In MI group, Wistar rats were undergone acute myocardial infarction by ligation of the anterior descending coronary artery. Sham operation was made in rats as control. The mRNA expression of collagen and cytokines such as TNF-α and TGF-β1 in infract and non-infarct region of left myocardium were detected by RT-PCR at different time point (3 d, 1 and 4 weeks). RESULTS:Collagen type Ⅰ and Ⅲ elevated as well as the TNF-α and TGF-β1 in the MI group at 3th day. Expression of collagen type Ⅰ and Ⅲ were higher in the infarct region than that in the non-infarct region even at 4 weeks. TNF-α and TGF-β1 peaked at 1 week and declined gradually to the baseline, which was still higher than those in control group (P<0.01). Correlation analysis revealed that expressions of TNF-α and TGF-β1 were positively correlated with the collagen type Ⅰand Ⅲ (P<0.01). CONCLUSION:Cytokines participate in the myocardial remodeling after MI. Interfering with expression of cytokines may be the potentially preventative method in the myocardial remodeling.     

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.     

Comparison between mobilization and transplantation of bone marrow stem cells for the therapy of myocardial infarction in rabbits

AIM: To compare bone marrow stem cell mobilization with bone marrow-derived mononuclear cells (BMCs) transplantation for the therapy of myocardial infarction (MI) in rabbits, and to explore more effective and practical stem cell therapeutic strategy for MI. METHODS: In mobilization group (M, n=10), granulocyte-colony stimulating factor (G-CSF) (30 μg·kg-1·d-1) was injected subcutaneously 3 hours after MI and every 24 hours for 5 days. On the 5th day, the BMCs from 10 mL peripheral blood were labeled with bromodeoxyuridine (BrdU) for 24-48 hours, then reinjected intravenously. In transplantation group (T, n=10), BMCs transplantation was performed 5-7 days after MI. After being obtained from bone marrow (3-5 mL) of iliac crest and labeled with BrdU for 24-48 hours, BMCs were transplanted into infracted myocardium through intramyocardial injection. Control animals (C, n=10) did not receive any treatment after MI. Echocardiography were performed for the evaluation of cardiac function 1 week and 5 weeks after MI. Hemodynamic studies and histological study were performed 5 weeks after MI. RESULTS: LV ejection fraction increased significantly in group M, had no change in group T, and decreased 1 week and 5 weeks after MI in group C. Group M and group T had higher LV max +dp/dt and max -dp/dt, lower LV end-diastolic pressure compared with group C 5 weeks after MI. Histological studies revealed that there were BrdU positive cells in the infarcted area in group M and group T. The vascular density of group M and group T in the infarcted area was significantly greater in comparison with group C. No regeneration of smooth muscle cells and cardiomyocytes were found in the infarcted area. CONCLUSION: Bone marrow stem cell mobilization with G-CSF and transplantation of BMCs both significantly improve the cardiac function for the therapy of MI through vascular genesis in the infarcted area. Bone marrow stem cell mobilization may offer a new and non-invasive therapeutic strategy for MI.     

Transplantation of exogenous adipose tissue derived mesenchymal stem cells for treatment of acute myocardial infarction in rat

AIM: To establish a method of isolating,culturing the adipose tissue-derived mesenchymal stem cells in vitro and to investigate the possibility of exogenous transplanting the adipose tissue derived mesenchymal stem cells for treatment of rat acute myocardial infarction.METHODS: 18 male rats were separated randomly into 3 groups: sham surgery group (control,n=6),acute myocardial infarction control group (AMI,n=6) and myocardial infarction plus cell transplantation group (AMI+cell,n=6).The infarcted hearts were made by occlusion of left coronary artery.The mesenchymal stem cells were isolated from the rats’ peritoneum by using digestion methods and reproduced in vitro,then the cells were labeled with BrdU and implanted into the infarcted heart of the rats.Heart functions were measured 4 weeks after implantation.The hearts were also harvested for pathological and histoimmunochemical observations to determine the survival and location of the implanted cells.RESULTS: Plenty of mesenchymal stem cells were obtained from the adipose tissue of rats’ peritoneum.Compared with the AMI group,the left ventricular systolic pressure in the cell therapy group was increased significantly (P<0.01),the left ventricular end-diastolic pressure was decreased (P<0.01),and the ratio of the left ventricular pressure rise and decay (±dp/dt) was decreased (P<0.05).The number of blood vessels was increased at the boundary of infarction site by pathological observation.The labeled cells were founded in the infarcted myocardium and the blood vessel wall.CONCLUSION: The adipose tissue is a new optional stem cell source.The methods of exogenous transplantation of adipose tissue derived mesenchymal stem cells for treatment of AMI is effective and feasible.     

Effects of PPARα and fenofibrate on actue myocardial damage induced by isoproterenol in rats

AIM:To investigate the effects and mechanism of PPARα and its actor fenofibrate (FF) on injury caused by myocardial ischemia in rats. METHODS:The experimental animals were randomly divided into control group, isoprenaline (ISO) group and FF group. Actue myocardial injury caused by intraperitoneal injection of isoprenaline to induce ischemia was established. The following changes were measured: the level of creatine kinase (CK) and lactic dehydrogenase (LDH) in serum, the activity of myocardial myoperoxidase (MPO), the changes of serum TNF-α by ELISA and the level of PPARα mRNA by RT-PCR. RESULTS:As compared with ISO group, FF depressed significantly the release of CK and LDH in serum, alleviated significantly myocardial inflammation, depressed the changes of serum TNF-α, obviously increased the level of PPARα mRNA in the isoprenaline-induced injury in rat heart (P<0.01). CONCLUSION:These results suggest that FF may inhibit myocardial inflammation and exert protective effects on the acute myocardial ischemia injury induced by ISO in rats. PPARα may mediate the modulation of the inflammatory reaction.     

Effects of HES 130/0.4 on no-reflow after myocardial ischemia-reperfusion injury in rats

AIM: To observe the effects and mechanisms of hydroxyethylstarch(HES) 130/0.4 on no-reflow phenomenon after myocardial ischemia-reperfusion in rats. METHODS: SD rats were randomly divided into 4 groups:sham operation group, ischemia-reperfusion(IR, treated with normal saline) group, normal saline ischemia-reperfusion(NS-IR, treated with NS) group and HES ischemia-reperfusion(HES-IR, treated with HES) group. Myocardial infarct size and no-reflow range were determined by staining methods, and the activities of myocardial enzymes(CK-MB, cTnI and MPO) were measured. Meanwhile, cardiac microvascular endothelial cells of the rat were cultured and divided into 4 groups:control group, hypoxia/reoxygenation(H/R) group, NS-H/R group and HES-H/R group. Acute ischemia reperfusion models were simulated, and the concentration of calcium ions was measured. The relative cell activity was evaluated by CCK-8 assay, and the apoptotic rate was detected by flow cytometry. RESULTS: In HES-IR group, the myocardial infarct size, the no-reflow zone, CK-MB, cTnI and MPO activity were all significantly lower than those in IR group(P<0.05). In microvascular endothelial cells, the concentration of calcium ions and the apoptotic rate in HES-H/R group were significantly decreased, while the relative cell activity increased compared with H/R group(P<0.05). CONCLUSION: HES reduces no-reflow in acute myocardial ischemia-reperfusion. The mechanism may be involved in the inhibition of both the infiltration of neutrophils and the calcium overload of endothelial cells.     

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.     

Cardiomyocyte apoptosis and related gene expression after acute myocardial infarction in rats

AIM: To investigate cardiomyocyte apoptosis and the expression of caspase-3, Bcl-2 and Bax after acute myocardial infarction (AMI) in rats.METHODS: AMI model was established with the ligation of left coronary artery in 78 randomly selected female SD rats.Twenty-four hours after operation, 43 survivors were randomly divided into 48-hour and 4-week two groups according to the time points: MI 48 h (n=11) and MI4 weeks (n=13) groups, sham-operated rats (S, n=27) were also randomly selected and reassigned to S48 h (n=10) and S4 weeks (n=10) groups.Cardiomyocyte apoptosis was detected with in situ terminal deoxynucleotidyl transferase (TdT)-dUTP nick-end labeling (TUNEL staining) and DNA gel electrophoresis.Caspase-3, Bcl-2 expression and Bax expression were detected with immunohistochemistry and Western blotting analysis.RESULTS: Compared with sham-operated group, after AMI, systolic, diastolic, and mean arterial blood pressures (SBP, DBP, MAP), left ventricular systolic pressure (LVSP) and the maximum change rate of left ventricular pressure rise and fall (±dp/dt) were significantly decreased (P<0.05, P＜0.01), while left ventricular end diastolic pressure (LVEDP) was significantly increased (P<0.05) in MI 48 h group.All the above indices in MI 4 weeks group had the same change as that in MI48h group, with the LVEDP significantly higher (P<0.01), except for a non-significantly change in SBP, DBP and MAP (all P>0.05).In both MI 48 h and MI 4 weeks groups, myocyte apoptotic index was significantly increased in the infracted/scar, border and non-infarcted areas (P<0.05,P＜0.01) with caspase-3 and Bax expressions increased significantly (P<0.05, P＜0.01) in myocytes of the above three areas and Bcl-2 expression increased only in myocytes of the infracted area in MI 48 h group.Western blotting indicated that Bcl-2/Bax ratio was also decreased in MI 48 h subgroup.CONCLUSIONS: After AMI in rats, cardiomyocyte apoptosis happened in the infarction/scar, border and non-infarcted areas, with caspase-3 and Bax expression in myocytes increased, and with Bcl-2 expression increased in myocytes of infracted area and Bcl-2/Bax ratio decreased only early after AMI.     

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.     

Changes of adiponectin and adiponectin receptor 1 in diabetic rats of different courses during myocardial ischemic preconditioning

AIM: To investigate the different effects of adiponectin (APN) and adiponectin receptor 1 (Ad-R1) on myocardial ischemia-reperfusion (IR) injury and ischemic preconditioning (IPC) in different course of diabetic rats in vitro. METHODS: The rat models of type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM) were successfully established using streptozotocin and high-fat diet plus streptozotocin, respectively. These rats were divided into 2 groups:4 weeks and 8 weeks. The model of isolated cardiac perfusion was established by Langendorff method. Each group was further divided into control (Con) group, IR group and IPC group. The activity of lactate dehydrogenase (LDH) and creatine kinase (CK) in coronary effluent was detected. The serum and myocardial levels of APN were determined by ELISA. The expression of Ad-R1 in the myocardial tissues was detected by Western blot. The area of myocardial infarction was detected, and the ultrastructure of ventricular papillary muscle was observed by transmission electron microscopy. RESULTS: Compared with the corresponding IR group, the activity of LDH and CK in the IPC group at 4 weeks was significantly decreased (P<0.01), and the area of myocardial infarction was significantly reduced. However, no significant difference of each index in DM groups at 8 weeks was observed. Serum APN level was decreased in diabetic rats, especially in T2DM rats (P<0.05). The levels of APN and Ad-R1 in myocardium of normal rats had no difference among Con, IR and IPC groups. The level of APN in myocardium of T1DM rats had no difference in all subgroups, while the expression of Ad-R1 in myocardial tissue of IR group was significantly increased as compared with Con group (P<0.01) and IPC group (P<0.01) both at 4 and 8 weeks. In T2DM rats, the levels of APN in myocardium both at 4 and 8 weeks were decreased in IR group compared with Con group (P<0.05). The level of APN in IR group at 4 weeks was significantly decreased compared with IPC group, but had no significant difference at 8 weeks. The expression of Ad-R1 in myocardial tissue of IR group was significantly increased compared with Con group (P<0.05) both at 4 and 8 weeks. The level of Ad-R1 in IR group at 4 weeks was significantly increased compared with IPC group (P<0.05), but had no significant difference at 8 weeks. CONCLUSION: The protective effect of IPC exists in diabetic rats at 4 weeks, whereas it disappears at 8 weeks. APN and Ad-R1 in myocardium were probably involved in the protective effect of IPC on T2DM rats.     

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.     

Change of calcium sensing receptor expression and apoptotic pathways in myocardial infarction rat induced by isoprel

AIM:To observe the change of calcium sensing receptor (CaSR) expression and apoptotic pathways in myocardial infarction rat induced by isoprel.METHODS: The myocardial infarction rat models were prepared by subcutaneous injection of isoprel (ISO 200 mg·kg-1·d-1 for 2 d). Wistar rats were divided into three groups randomly: ① Control group; ② ISO/1d group; ③ ISO /2d group. The expressions of CaSR, 〖STBX〗bcl-2, bax〖STBZ〗 and caspase-3 mRNA and protein were analyzed by RT-PCR and Western blotting, respectively. Apoptotic cells were measured by TUNEL staining assay. The morphological and ultrastructural changes were observed under optical microscope and electronic microscope. The activity of LDH, CK, SOD and the content of MDA were assayed with ultraviolet spectrophotometer. The level of troponin(cTnT) was observed by chemical immunofluoresence.RESULTS: Compared with control group, the activity of LDH and CK, the content of MDA and cTnT, the apoptosis index and the expression of CaSR, Bax and caspase-3 were reached the highest level, but the SOD activity and Bcl-2 expression were decreased. The myocardial ultrastructural injury was aggravated in the ISO/1d group. The change of above parameters in ISO/2d group was between control and ISO/1d group.CONCLUSION:The increased expression of CaSR is involved in rat myocardial infarction induced by isoprel, which is related with oxidative stress and apoptosis.     

Preventive effect of Sini decoction on expression of TGF-β1 in rat myocardiac fibrosis induced by isoproterenol

AIM: To explore the protective effects of Sini decoction (SD) on myocardial fibrosis induced by isoproterenol (Iso) in rats.METHODS: Nineteen Wistar rats were divided into Iso group, SD treatment group and control group. The rats in Iso group were injected with Iso and were then fed with saline. The rats in SD treatment group were injected with Iso and were then fed with SD. The rats in control group were injected with saline and were then fed with saline. The level of hydroxyproline (Hyp), the contents of angiotensin Ⅱ (AngⅡ) and transforming growth factor beta-1 (TGF-β1) in plasma were measured 4 weeks after administration. TGF-β1 at mRNA and protein levels were measured by the techniques of ELISA and RT-PCR. RESULTS: The plasma levels of TGF-β1 and AngⅡ were lower in control group than those in Iso group and SD treatment group (P<0.05). The plasma levels of TGF-β1 and AngⅡ in SD treatment group were lower than those in Iso group (P<0.05). Compared to Iso group, the cardiac diastolic function was significantly improved in SD treatment group (P<0.05). The results of immunohistochemistry and RT-PCR showed that the mRNA and protein expressions of TGF-β1 were lower in SD group than those in Iso group (P<0.05). CONCLUSION: SD alleviates myocardial fibrosis induced by Iso in rats by decreasing TGF-β1 expression at mRNA and protein levels.