A new biodegradable stent made of magnesium alloy in preventing stenosis in the common bile duct probe

Objective: To design a new type of biliary stent to be used in the common bile duct probe and evaluate its biocompatibility, safety and effectiveness in a canine model. Methods: Magnesium alloy (AZ 31B) was used to make biliary stents. A canine model of acute obstructive jaundice was established by ligating the distal end of the common bile duct. These dogs were divided into two groups with either placement of magnesium stent or not. The incidence of bile duct leakage and survival were evaluated. Meanwhile, we determined the concentration of magnesium in various body fluids and organs, liver function test, and ultrasonic and histological studies. Results: The concentrations of magnesium in the blood, feces, liver, heart, brain and lungs were similar between the two groups. Bile leakage rate in experimental group and control group was 0% and 16.7%, respectively. The mortality was 16.7% and 33.3%. There were no significant differences in ALP and TBIL between experimental group and control group (P>0.05) before building and bile duct exploration. There were significant differences in ALP and TBIL between the two groups one and three months after bile duct probe (P<0.05). Biliary tract specimens showed obviously anastomotic stenosis performances and expansion performances of extrahepatic biliary in the control group, but in experimental group such changes were not observed. Ultrasonography showed that the patency of biliary anastomosis was good and there was no anastomotic biliary stricture in experimental group. However, progressive stenosis and expansion performances of extrahepatic biliary occurred in control group. There were fewer collagen fibers but more muscle fibers in experimental group than in control group. Conclusion: Biliary stent made of magnesium alloy is of good biocompatibility and has the potential to prevent the postoperative stenosis in the common bile duct probe.