Experimental Research On Biodegradable Paclitaxel Bilioenteric Stent Prevent Bilioenteric Anastomotic Stricture In Porcine Model

Part 1Designing and manufacturing a novel biodegradable paclitaxel double coating bilioenteric stentObjective Designing and manufacturing a novel biodegradable paclitaxel double coating bilioenteric stent with a biodegradable elastic material.Methods Choosing a synthetic polymer called elastic body as the covering material,which was provided by the institute of polymer science of Zhejiang University and synthesized with L-LA and?-CL. Paclitaxel in a powder form can be easily mixed in with the tetrahydrofuran (THF) solution,which is used as a solvent for elastic body. The bilioenteric polylactide stent was dipped in a container filled with elastomer-paclitaxel THF solution and heat dried whereafter (internal coating). Then the stent was dipped in another container filled with elastomer THF solution and heat dried again(external coating).Result Manufacturing a novel biodegradable paclitaxel bilioenteric stent,with the use of a biodegradable elastomer as covering material and a double coating as design.Conclusion Designing and manufacturing a novel biodegradable paclitaxel double coating bilioenteric stent. Part 2The drug release in vitro for biodegradable paclitaxel eluting stent measured by HPLCObjective To establish HPLC method for determinating paclitaxel release of the biodegradable paclitaxel eluting bilioenteric polylactide stent in vitro, and to determinate the release rate of paclitaxel in biodegradable paclitaxel eluting stents with different layers of blank external coating.Methods The biodegradable paclitaxel eluting stents were grouped into four groups based on the layers of blank external coating(0-3 layers). Every group had 3 samples. Every stent was placed in 3ml phosphate buffered saline solution with 0.01%Tween80. phosphate-buffered solution was changed every one day for 20 days and the daily amount of paclitaxel released was measured by high-performance liquid chromatography. The extraction was performed with DCM and dried at normal temperature, the residual was reconstituted with mobile phase, and injected 20ul for assay. The concentration of paclitaxel was assayed on a Dikma-C18 column with a mobile phase consisting of methanol-acetonnitrile-water(58:37:5) at a flow rate of 1 ml/min, detected at 230nm.the column temperature was set at 25?. The extraction was performed with DCM and dried at normal temperature, the residual was reconstituted with mobile phase, and injected 20?L for assay.Result A linearity was obtained from 0.1 to 30ug/ml with a good correlation, specificity, accuracy and recovery rate. The biodegradable paclitaxel eluting stent released paclitaxel by inches. The blank external coating could delay the release of drug. The biodegradable paclitaxel eluting stent coated with 2 layers of blank external coating started to release drug visibly in day 7-9.Conclusion It was a sensitive and simple method for determinating paclitaxel release of the biodegradable paclitaxel stent in vitro. The blank external coating could delay the release of drug. Part 3The effect of a biodegradable paclitaxel double coating bilioenteric stent on the healing process of bilioenteric anastomosis in porcine modelObjective To observe the effect of a biodegradable double coating bilioenteric stent on the healing process of bilioenteric anastomosis in porcine model, especially to evaluate the preventive effect on anastomotic stenosis.Methods Choosing Bama miniature pig as experimental subject, with simulation of the surgical procedure of Roux-en-Y bilioenteric anastomosis, which is commonly used in clinic. A porcine bilioenteric anastomosis model was construced. Twenty-four swines were randomly divided into two groups evenly in this experiment. Experimental group was dealed with double coating stents and contron group with bare stents. Animals were sacrificed at 1,3 and 6 months after operation. The anastomotic wound healing was observed. Bursting pressure, diameter of anastomosis and liver function were measured and compared between the two groups. The status of scar formation, cholangiography. histologic findings by HE,Masson staining and electron microscope were evaluated. The expression of a-SMA, TGF-?1 and b-FGF were also performed and compared.Result All operation were accomplished successfully.There was no death during or after operation. No obvious leakage happened in either experimental or control group. There was no significant difference of the serum levels of ALT, AST, ALP and TBIL between experimental group and control group at one, three and six months after operation.(P>0.05). Cholangiography indicates that there was mild dilatation of common bile duct and intrahepatic bile duct in one pig of control group at six months after operation. Both HE stain and Masson stain show that inflammatory reaction and hyperplasia of the bile duct wall in the paclitaxel group was much more moderate than that in control group. Immunol histochemistry and quantitative PCR showed that experimental group had less expression of-SMA and TGF-?1 than control group at one, three and six months after operation. The amount of expression of b-FGF in experimental group was significant higher than that in control group. Conclusion The biodegradable paclitaxel double coating bilioenteric stent could prevent bilioenteric anastomosis from stenosis in porcine model to a certain degree.