Biodegradation characteristics of a new kind of drug-eluting biodegradable ureteral stent in vivo and in vitro

Abstract

Objective To observe the degradation characteristics of the novel drug-eluting biodegradable polylactide ureteral stents in vivo and in vitro, and to compare biocompatibility differences of the pure biodegradable ureteral stents with paclitaxel-eluting biodegradable ureteral stent. Methods The polylactide ureteral stents were dipped into fresh urine specimen and urinary environment simulated in vivo by shocks. And in vivo these two kinds of ureteral stents were implanted in the dorsal muscle of 16 Wistar rats. Histological study was used to investigate the tissue reaction of the material and the differeces of these two kind of ureteral stents were evaluated. Scanning election microscopy (SEM) and measurement of gravity and molecular weight were performed to make out the biodegradation characteristics of stents in vitro and in vivo. Results After being soaked in human urine for 10 weeks, weight of the novel drug-eluting stents was decreased by 35%. Under the SEM, the surface of ureteral stent lost its original shape, shedding a large number of blocks. Histological staining found that fibrosis of drug-eluting biodegradable ureteral stent was mild. After 12 weeks, it was degraded into small sand-like particles. The fiber membrane thickness of pure stent was (21.24 ±3. 27) μm and of drug-eluting stents was ( 10. 75 ±3.69) μm. There was significant difference between two groups (P ＜ 0. 01 ). Conclusion The biodegradation of drug-eluting stents is similar to pure biodegradable ureteral stent, but the inflammatory reaction of the former is minor and the fiber membrane is thinner. The drug-eluting stent has better histocompatibility and can be used for stenting after a ureteral repair. Key words: Ureter; Stent; Biocompatibility