Degradation Pattern,Mechanical Property And Biosafety Research Of Biodegradable Magnesium Alloy Biliary Stent

ObjectivesMaking use of the vitro microenvironment of biliary system,combined with vivo experiments,to study the mechanical properties,degradation rate and biosafety of biliary stents made of biodegradable JDBM magnesium alloy,and to make a comprehensive evaluation.Methods1.Hand-woven magnesium alloy stent were given electrochemical polishing and then made fluoride and coated with poly-lactic acid using the dipping-lift method.2.In the contrast of one Nickel titanium alloy stent,7 naked magnesium alloy stents and 7 coated were tested on radial force.The different radial force when it reached a compression of 50%was competed.3.7 naked magnesium alloy stents and 7 coating on magnesium alloy stents were separately placed into the vitro bile perfusion system.Quality and morphology changes were monitored weekly.4.Beagles were operated to set up an incomplete obstruction model.3 naked magnesium alloy stents and 3 coated were placed into bile common duct.Blood was tested weekly.On the 15^th,30^th and 60^th,one beagle was given to death after local bile duct tissues were taken out.The degradation of stents and the obstruction of bile duct were examined.Tissues were prepared for pathological examinations.5.The standard method of leaching solution was used to deal with naked magnesium alloy and coating pills,normal culture group as negative control group,L929 mouse fibroblasts were cultured in H-DMEM medium containing 10%fetal bovine serum.Then CCK-8 method was used to detect the cell proliferation activity of different time.Serology detection was given to Canines regularly;liver,spleen,lung,and kidney tissues were taken for pathological observation when experiments ended.Results1.The radial force of naked magnesium alloy stents and the coated proved no significant statistical difference?p>0.05?,but was superior than that of the nickel titanium alloy stent?p<0.05?.2.The rate of mass loss of naked magnesium alloy stents group was obviously higher than that of coated group.The difference had the obvious statistical significance?p<0.05?.3.The model of incomplete obstruction of common bile duct was established successfully.ALT and AST increased significantly after 2 weeks,and there was a statistical significance?p<0.05?.2 weeks after stents were implanted,the liver function index of Canines declined obviously.There was no significant statistical difference?p>0.05?between the naked and the coated group.On the 15^th and 30^th day,the remainings of coated stents were more than that of the naked ones.On the 60^th day,there were nothing remained in both group.4.The cell proliferation activity was tested in CCK-8 method.There was no significant statistical difference between naked group,coated group and negative control group.Beagles'hearts,spleens,lungs and kidneys were pathological tested,and there were no obvious pathological changes,serum magnesium ions concentration was normal?p>0.05?.Conclusions1.This type of JDBM magnesium alloy biliary stent was superior than titanium alloy stent,and the coating has no effect on its mechanical properties.2.In vitro bile perfusion system,the weight-lost rate of coated group was significantly lower than the naked group.The coating protected the magnesium alloy from degradation.3.Magnesium alloy biliary stents performed worse in vivo than in vitro on biodegradation.But the coated group was better than the naked group on degradation.4.JDBM magnesium alloy and the coating of fluoride magnesium and polymerization of lactic acid performed well on biosafety.