The Experimental Study Of Low Molecular Weight Heparin-eluting Covered Stent Preventing Restenosis

Part ⅠLow Molecular Weight Heparin Inhibits the bFGF -induced Proliferation of Canine Vascular Smooth Muscle Cells in VitroObjective To determine whether Low Molecular Weight Heparin (LMWH)inhibits the bFGF-induced proliferation of canine arterial smooth muscle cells(SMCs) in vitro.To assese the most effective concentration of LMWH. Methods 1.MTT test:Canine VSMCs(5X103/well) were cultured in DMEM+10%FBS medium containing 10ng/ml bFGF.Added LMWH to the cell culture medium in the concentration of 0,10,50,100,200,400,800,1000,2000anti-XaIU/ml respectively.After 72hours,all groups underwent MTT test.Calculated the inhibiting rates of all groups.Determined the most effective concentration of LMWH. 2.Discribed the growing feature of VSMCs in different experiment medium by growth curves.3.Analysis of cultured VSMCs by flow cytometer.4.Observation of ultrastruture of VSMCs inhibited by LMWH with transmission electron microscope.5.Assessment of the inhibitive effect of LMWH to VSMCs by immunohistochemical method.6.Show the changes of VSMCs in cell cycle induced by bFGF,and effects of LMWH to cell division with HE stain.Results 1.The inhibitive effect of LMWH is in direct proportion to the concentration of it.In bFGF-induced proliferation group,inhibiting rate of 1000anti-XaIU/ml LMWH is greater than 50%.2.Flow cytometer examination shows LMWH block theVSMCs' cell cycle in S-phase,the ratio of VSMCs in G2-M phase descents.3.No sign shows apoptosis of VSMCs.4.LMWH inhibits the expression of PCNA induced by bFGF.5.LMWH inhibits the mitogenic function of bFGF..Conclusions Identify the inhibitive effect of LMWH on VSMCs' prolifreration induced by cytokines expressing locally post-PTA.Obtain the lowest effective concentration of LMWH in vitro. Provide credible data for the futher study of local delivery of LMWH to prevent post-PTA restenosis.Key Words LMWH; bFGF; VSMCs; in Vitro; CaninePart ⅡBasic Study of Low Molecular Weight Heparin-eluting Polylactic-co-glycolide(PLGA) CoatingObjective To detect the most effective technics of LMWH-polymer coatings.To measure the degradation of coating quantitatively.To observe the surface morphology of coatings.Methods 1.Preparation of LMWH-PLGA coating of two kind of stent using different technique.2.Determination of the weight loss of the coating during degradation,calculating the weight loss rate.3.Measurement of LMWH-eluting rate by a UV spectrophotometer.4.Observation of the surface morphology of coatings by scanning electron microscopy(SEM).Results 1.The average mass of coating of bare stent is 283μg,carrying dosage of LMWH is 207.88μg;The average mass of coating of covered stent is 501.83μg,carrying dosage of LMWH is 305.25μg.2.Within first 20 hours, there was apparent weight loss of the coating,and then weight loss became slower gradually.3.The pattern of drug-eluting of two kind of coating is similar.In the early stage,drug-eluting rate is higher.Drug-elution correspond to the weight loss.4.The degradation of the coating begins from the inner to the outer,the outer layer appears intact at the beginning.The attachment force descends during the process.The coating of covered stent seem to attach more firmly than that of bare stent.Conclusions 1.The synthesis of PLGA and techniques of coating are successful.2.Average mass and drug dosage of covered-stents' coating are greater than those of bare stents'.Covered stent is a better platform of local drug-elution.3.LMWH-eluting from polymer coating lasts more than 30 days.4.The degradating pattern and therapeutic effect of LMWH-polymer coating need to be study further in vivo.Key Words LMWH; PLGA; Drug-eluting stent; Covered stent; in vitroPart ⅢThe Study of Low Molecular Weight Heparin-eluting Covered Stent Preventing Restenosis in Canine Iliac Artery Model⒈Creation of Restenosis Model on Canine Iliac ArteryObjec...