Abstract: Objective To evaluate the in situ biocompatibility of a new biodegradable ureteral stent made of L-lactide-glycolic acid copolymer 80:20(PLGA 80:20). Methods 16 dogs served as experimental animals. Ureteral stents of PLGA 80:20 were inserted in situ into the left ureter after transection at the mid level, then the ureters were routinely anastomosed. Ureters surrounding the stent were taken out 2,4,8 and 12 weeks postoperatively. The ureters were dissected to find changes of stents and local ureters. Histological analysis was performed to investigate tissue reactions to the stent and evaluate the biocompatibility. Rods of UROVISION stent served as controls. Results The PLGA stent was degraded completely within 12 weeks post implantation. In the early stage (2～4 weeks), both stents induced epithelial hyperplasia and inflammatory cell reaction at local ureter （P>0.05）. In the later stage (8～12 weeks), the tissue reaction nearly subsided in PLGA stented ureters after degradation of the device. Whereas, the tissue reaction induced by UROVISION stent had lasted throughout the observation period, even deteriorated with time going（P<0.05）. Conclusion The tissue reaction induced by PLGA stent is retrievable. PLGA is regarded highly compatible and can serve as an ideal material for biodegradable ureteral stent.

Key words: biocompatible, ureter, stents, biocompatible materials