Characterization of novel biodegradable ureteral drug-eluting stent

Objective To build a new biodegradable ureteral drug-eluting stent (DES), and investigate its degradation characteristics, drug release property and histocompatibility in vivo and vitro. Methods Two typical specimens were constructed with Poly-L-Lactide (PLLA), Poly-DL-Lactide (PDLLA) and rapamycin. The flaky specimens were dipped into fresh urine sample with gentle agitation in vitro. Scanning Electron Microscope (SEM) and mass measurement were performed to investigate the biodegradation characteristics of stents, and High-Performance Liquid Chromatography (HPLC) was performed to investigate the drug release property of stents at 2, 4, 6, 8, 10, 12 weeks after agitation. The DES was implanted in the dorsal muscle of 6 rabbits. The histocompatibility of DES was assessed by histology and image analysis system at the first, fourth and twelfth week. Results After being dipped in human urine for 6 weeks, a few of white floaters were found and the weight of flaky specimens were decreased by 15%. Under the SEM, small holes were found on the surface of specimens. The drug loading of initial state, 2, 4, 6, 8 and 10 weeks group were (1 425±47) μg, (1 400±23) μg, (1 368±55) μg, (1 278±88) μg, (780±32) μg and (362±36) μg, respectively. There were no significant differences in drug loading between initial state and 2 weeks group, 2 weeks group and 4 weeks group (P> 0.05). Meanwhile, the drug loading of 6 weeks group detected by HPLC was significantly lower than 4 weeks group (P< 0.05), and the drug loading of 8 weeks group and 10 weeks group were significantly lower than that of the former groups (P< 0.01). The results of histology showed that the acute inflammatory reactions were mild and the fibrous tissue proliferated slightly at the twelfth week. Conclusion The degradation characteristics, drug release property and histocompatibility of new biodegradable ureteral drug-eluting stent can meet the requirements of the repair of human ureteral injury.