METALLIC STENT MESH COATED WITH AG NANOPARTICLE SUPPRESSES STENT-INDUCED TISSUE HYPERPLASIA AND BILIARY SLUDGE IN RABBIT EXTRAHEPATIC BILE DUCT

Aims Current therapeutic strategies are insufficient for suppressing stent restenosis after biliary stent placement. The effects of silver nanoparticles (AgNPs) coated metallic stent mesh for suppression of stent-induced tissue hyperplasia and biliary sludge formation in the rabbit extrahepatic bile duct were investigated.

Methods Meshes of self- expandable metal stent (SEMS) were coated with three different concentrations of AgNP to enable antibacterial and anti-inflammatory activities. Twenty-four rabbits were randomly divided into four groups of six each. Group A received bare uncoated SEMS. Groups B, C, and D received AgNP-coated SEMS of 3, 6, and 12 mg/mL of Ag concentration. The effectiveness of AgNP-coated SEMS was accessed by comparing the results of cholangiography, gross, and histological examination.

Results AgNP-coated SEMSs were successfully fabricated using two-step synthesis. SEMS placement was technically successful in 22 of 24 rabbits. Two rabbits were excluded because of procedure-related death. Sludge formation in AgNP-coated SEMS groups was prominently decreased compared with the control group on gross findings. Cholangiographic and histologic examinations revealed significantly less stent-induced tissue hyperplasia in AgNP-coated SEMS groups than in the control group (p < 0.05 for all). There were no significant differences of cholangiographic stenosis or percentage of granulation tissue area between AgNP-coated SEMS groups (p > 0.05 for all). However, the thickness of submucosal fibrosis in group D was higher than that of groups B and C (p < 0.05 for all).

Conclusions SEMS with AgNP-coated stent mesh suppressed stent-induced tissue hyperplasia and biliary sludge formation in the rabbit common bile duct. AgNP concentrations of 3 to 6 mg/mL are preferable for Ag nano-functionalized SEMS to prevent these phenomena.