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Objective:To fundamentally solve the problems of valve dysfunction caused by limited size of artificial valve, high requirements for implantation technology, destruction of subvalvular structure and proliferation of fibrous endothelial tissue. We have developed a prosthetic valve with zero left ventricular occupancy. The valve frame is appropriately higher than the existing products, slightly chimney shaped, fully accommodates the movement of the valve leaves in the valve frame, and completely supraannular surgical implantation. This study uses this valve for preclinical animal test.Methods:Seven sheep underwent the replacement of the artificial valve under the direct vision of cardiopulmonary bypass. Warfarin was used for anticoagulation for 6 months 24 hours after operation. The blood biochemistry, anticoagulation and cardiac color Doppler ultrasound were detected after operation. The sheep were killed 180 days later for autopsy to observe whether the artificial valve caused thromboembolism. The efficacy and safety of valve were observed.Results:Two of the seven sheep died within 24 hours after operation, and five survived for a long time. Later, they were killed at 180 days. The mechanical properties of the artificial valve were good, and there was no thromboembolism around the artificial valve and important organs. The tissue layer of suture ring has been completely organized and endothelial cells, and the thickness of tissue layer is about 0.6-1.0 mm. The mitral valve of experimental animals can be opened and closed freely, with smooth surface and no abnormal echo. The follow-up of color Doppler ultrasound showed that the left ventricular ejection fraction was normal (0.60-0.70) before and 6 months after operation. The results of cross valve pressure difference and blood flow velocity of artificial valve were good (vmean was far lower than 5 mmHg(1 mmHg=0.133 kPa) and pmean was lower than 1 m/s) , suggesting that the hemodynamic performance of artificial valve was good. Left ventricular retrograde angiography showed that the artificial valve was completely located in the left atrium with good position and normal opening and closing. There was no obvious perivalvular leakage and other abnormalities. Within 7 days of blood test, the indexes of surgical stress were more abnormal than those before operation. At 12 and 24 weeks, there were no obvious abnormalities in blood routine test, liver and kidney function and other blood test indexes of animals in each group.Conclusion:The new chimney shaped mechanical valve implanted completely above the mitral annulus has good wear resistance, histocompatibility, antithrombotic and hemodynamic performance.
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Objective: To explore the effect of exercise preconditioning (EP) on pathological cardiac hypertrophy and heart failure (HF) in pressure over-loaded experimental rats. Methods:A total of 60 SD rats at the age of 6 weeks were randomly divided into 3 groups, n=20 in each group. Sham-operation group, Transverse aortic constriction (TAC) group and EP + TAC group. The cardiac function and structure were evaluated by echocardiography, patholgical changes and HF biomarkers were examined for EP effect at 4 and 8 weeks after TAC. Results:Compared with Sham-operation group, the cardiac function and structure had obvious changes in the other 2 groups. Compared with TAC group, the ejection fraction in EP+ TAC group increased 15%, the heart weight index and left ventricular weight index decrease 15.7%and 20%respectively at 8 weeks after TAC, all P Conclusion: EP may improve cardiac pathological hypertrophy in pressure over-loaded rats at the early stage, and delay the heart failure process.
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BACKGROUND:Our preliminary study found that the monocusp valves made of ultramicropore expanded polytetrafluoroethylene (ePTFE) revealed no significant thrombus, calcification, or degradation 20 weeks after implanted into the descending aorta and the left pulmonary artery in sheep, which verified the good property of ePTFE. However, the surface of ePTFE in the left pulmonary artery was covered with obvious neointima. OBJECTIVE: To assess the biocompatibility of phosphorylcholine-coated ePTFE. METHODS:ePTFE surface was modified by phosphorylcholine derivative. Then the changes of surface shape, tensile stress at yield and elasticity modulus, water contact angle, and protein absorption capacity of ePTFE after surface modification were observed. (1) Hemolytic test: the leaching solution of phosphorylcholine-coated ePTFE, leaching solution of uncoated ePTFE, normal saline, and distiled water were added to the diluted human blood, respectively. (2) Platelet count test: the phosphorylcholine-coated ePTFE, uncoated ePTFE, high density polyethylene, and Zymosan A were added to the whole blood samples from healthy volunteers, respectively. (3) Platelet activation test: the phosphorylcholine-coated ePTFE, uncoated ePTFE, γ-Globulins, and Zymosan A were added to the whole blood samples from healthy volunteers, respectively. RESULTS AND CONCLUSION: The mean micropore diameter of ePTFE was significantly decreased after phosphorylcholine coating (P significantly strengthened after phosphorylcholine coating (P ePTFE in biomechanical properties and hemolytic test. The platelet count test and platelet activation test demonstrated that phosphorylcholine coating significantly improved anti-thrombus function of ePTFE. So, phosphorylcholine coating can enhance anti-thrombus function, suppress protein adsorption, and improve biocompatibility of ePTFE.
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ObjectiveTo investigate the role of platelet in mouse pulmonary microvascular endothelial cell (PMVEC) injury caused by lipopolysaccharide( LPS)-activated neutrophil.MethodsPMVECs were obtained from pathogen-free C3H/HeN mice of both sexes aged 6-8 weeks weighing 18-25 g according to the method described by Lim YC et al.Platelets and neutrophils were isolated from mouse blood by twice centrifugation and denaity gradient centrifugation respectively.PMVECs were seeded into twelve- or six-well plates ( 1 or 2 ml/well) after 2-5 passages and were randomly divided into 4 groups (n =31 each): group LPS; group platelets (group P);group neutrophils (group N) and group platelets + neutrophils (group PN).Each well contained about 5 × 107/ml platelets and/or 5 × 105/ml neutrophils respectively.PMVECs were incubated with LPS1 μg/ml at 37 ℃ in a 5％ CO2 humidified atmosphere for 1,6,12,18 and 24 h respectively in all 4 groups.The cells were examined with phase contrast microscope for morphological changes and survival condition.Viability rate,apoptotic rate and activation rate of PMVECs were detected by flow cytometry at each time points.ResultsThere was no significant difference in morphology and number of endothelial cells (ECs) among the 4 groups,while the number of activated ECs was significantly increased but the number of living cells decreased in group PN compared with group LPS.The activation rate of ECs was significantly higher after being incubated with LPS for 6-12 h in groups P and N than in group LPS.The viability rate was significantly lower,while the apoptotic rate and activation rate were significantly higher after ECs were incubated with LPS in group PN than in groups LPS,P and N.ConclusionPlatelets play a decisive role in mouse PMVEC injury induced by LPS activated neutrophils.
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BACKGROUND: It has been found that xenogenic extracellular matrix (ECM) may cause a strong inflammatory response in humans during clinical application of decellularized porcine heart valve (synergraft valves). An early inflammatory reaction severely weakens matrix structure of valve wall, leading to structural rupture and decay of grafts. From Synergraft's event, the decellularized porcine heart valves still had immunogenicity, especially for pediatric patients. The mechanisms by which the ECM triggers this immune process need to be further evaluated. OBJECTIVE: To find the difference of gene sequence between human and porcine ECM and to identify the ECM immunogenicity based on bioinformatics. DESIGN, TIME AND SETTING: A contrast study between human and porcine ECM based on type IV collagen was performed at the Laboratory of Cardiothoracic Surgery, Changhai Hospital, the Second Military Medical University of Chinese PLA from June 2008 to February May.MATERIALS: The fresh porcine heart valves were obtained from Shanghai Wufengshangshi Slaughter House. Decellularized porcine aortic valves, hybridoma cells, and monoclonal antibodies were provided by our laboratory. METHODS: Similar region and conservative site of gene sequence among human, porcine, and rat were compared so as to look for common similar region, site, and sequence difference and investigate the segment which caused common and different gene sequence. Type IV collagen monoclonal antibody was used to evaluate the persistence of ECM of decellularized porcine heart valve following immunohistochemical staining. MAIN OUTCOME MEASURES: Type IV collagen gene sequence; efficacy of self-made antibody using immunohistochemistry; effect of self-made antibody on type IV collage of decellularized porcine heart valve. RESULTS: The differential gene serial in type IV collagen protein was found out by bioinformatics method. Monoclonal antibodies were successfully produced by human-mouse hybridoma technique. Residual porcine ECM was observed on decellularized porcine heart valve. CONCLUSION: Residual porcine ECM was observed on decellularized porcine heart valve and had immunogenicity.
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BACKGROUND: Hyperpolarization-activated cyclic nucleotide-gated (HCN) current plays an important role in regulating heart spontaneous pulsation.OBJECTIVE: To observe target gene expression and electrophysiological characteristics of pig bone marrow mesenchymal stem cells (BMSCs) transfected with hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) gene recombinant adenovirus.DESIGN, TIME AND SETTING: Cell-gene in vitro study was performed at the Laboratory of Thoracic and Cardiovascular Surgery,Second Military Medical University of Chinese PLA from July 2007 to March 2008.MATERIALS: Yorkshire pig was supplied by Animal Institute, Second Military Medical University of Chinese PLA. HCN2 plasmid was presented by Professor Dario DiFrancesco from Italy. Recombinant adenovirus Ad.HCN2 was constructed and stored using Ad5 in this laboratory.METHODS: Pig BMSCs were isolated with combination of gradient centrifugation of Percoll and adherent treatment in vitro.Ad.HCN2 was transfected at multiplicity of infection=50. We also set non-transfection and transfected Ad.Null groups.MAIN OUTCOME MEASURES: Expression of HCN2 mRNA was detected with RT-PCR, and expression of HCN2 channel protein was examined with immunofluorescent staining. Electrophysiology of HCN2 channel protein was measured with whole-cell patch clamp.RESULTS: No amplified fragments were found in the non-transfection and transfected Ad.Null groups, but amplified fragments were determined at 250-500 bp following Ad.HCN2 amplification, which was the same as plasmid carrying HCN2 gene. Staining strength of cell nuclei following transfection was significantly weaken compared with cell membrane and plasma, which showed identical distribution as HCN2 protein. No HCN2 protein was detected in the non-transfection and transfected Ad.Null groups.Pacemaker current could be recorded with a whole-cell patch clamp. It was fully activated around -140 mV with an activation threshold of -60 mV, presenting voltage dependence. CsCI (4 mmol/L) reversibly blocked the inward currents. No pacemaker current was detected in the non-transfection and transfected Ad.Null groups.CONCLUSION: The HCN2 recombinant adenovirus carrier was transferred into serial subcultivation porcine bone marrow mesenchymal stem cells. HCN2 channel protein has been expressing. Pacemaker current could be recorded with a whole-cell patch clamp.
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Objective To investigate the effect of the transplantation of autologous marrow mesenchymal stem cells transfected by angiogenin gene in a porcine chronic ischemic beart model.Methods Methods Mesenchymal stem cells were trnsfected byAd/Ang.The pigs underwent placement of amerold occluder around LCx and 4 weeks later sujected to transplantation of the trandected mesenchymal stem cells.The animals were evaluated by coronary angiography,echocardiography,mannetic resonance imaging end pathologic observation.Results All animal showed 95%occlusion fo LCx.4 weeks after treatment ,the perfusion of LCx,left ventricular ejection fracton were greatly evhanced.A large number of labeled mesenchymal stem cells were successfully uncorporated into blood vessels in the ischemic myocardial regions with increased vessels countin and survival of implanted cell.Conclusion Transplantaton of autologous mesenchymal stem cells trendected by angiogenin gene offere obvious advsntases of great improvement of blood supply and the heart funcition.
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Objective To investigate the influence of miR-203 on the proliferation and invasion of human esophageal squamous cell carcinoma cell line Eca109.Methods Double-stranded mimics of miR-203 were designed and transfected into Eca109 cells with Lipofectamine 2000;Eca109 cells transfected with nonsense microRNA mimics were taken as control.The proliferation ability of Eca109 cells was determined by calculating the cell population doubling time and the percentage of apoptotic cells;the invasion ability of Eca109 cells was determined by Transwell assay.Results In vitro experiment showed that,compared with the control group,Eca109 cells transfected with miR-203 mimics had a significantly longer cell population doubling time([26.1?0.5]h vs [24.2?0.6]h,P
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Objective:To modify the pulsatile bioreactor we constructed previously for simulating the high-flow, high-pressure hemodynamics of heart valve in vivo, and to experimentally cultivate the tissue-engineered heart valves (TEHV) in the modified bioreactor. Methods: T-PLS system (NewheartBio Co., Ltd Korea) was used to generate pulsatile flow in the modified bioreactor and we designed a new air-exchange pathway to avoid contamination. The TEHV were made by seeding human bone mesenchymal stem cells (BMSCs) on de-cellularized porcine heart valve. After cultured under static condition for 4 d, the TEHVs were moved to the modified bioreactor and exposed to low-flow (0-600 ml/min) or high-flow(0-4 800 ml/min) pulsatile hydrodynamics for 7d, then the cells on TEHVs were evaluated. Results: After modification, the flow range expanded from (0-1 200) ml/min to (0-6 000) ml/min and the pressure range expanded from (0-40) mmHg to (0-180) mmHg. In culture experiments, 26.3% of the seeded cells remained under low-flow environment and cells were completely lost under the high-flow dynamics. Conclusion: The modified bioreactor can basically simulate the dynamics of heart valve in vivo and can be used in TEHV cultivation research. However, the current TEHV can not tolerate the high-flow pulsatile hydrodynamics.