Characterization Of 2 Types Novel Biodegradable Ureteral Drug-eluting Scaffold Materials

Objectives1. To build two new types of biodegradable ureteral rapamycin-eluting scaffold materials.2. To investigate its degradation characteristics, drug release property and histocompatibility in vivo and vitro.Methods1. One typical drug-eluting material was constructed with Poly-L-Lactide (PLLA), Poly-DL-Lactide (PDLLA) and rapamycin, and another typical drug-eluting scaffold material was fabricated with polycaprolactone (PCL)/poly (lactic acid-glycolic acid) (PLGA) and rapamycin. Scanning Electron Microscope (SEM) and High-Performance Liquid Chromatography (HPLC) were performed to estimate the initial state of the scaffoldmaterials.2. Two types flaky scaffold materials were dipped into fresh urine sample with gentle agitation in vitro(37?,90rpm). SEM and mass measurement were performed to investigate the biodegradation characteristics of materials after 2,4,6,8 and 10 weeks. Meanwhile, the determination of drugloadingby HPLC was performed to investigate the drug release property of materials.3. The rapamycin-eluting scaffold materials were implanted in the dorsal muscle of rabbits. The histocompatibility was assessed by histology and image analysis system after 1,4 and 12 weeks.Results1. The mixed PLA drug-eluting scaffold materials and PGLC drug-eluting scaffold materials both have smooth surface, no cracks, no glitches in initial state under SEM. And there were no statistical differences between the two scaffold materials regarding the drug loading dosage (P>0.05).2. After being dipped in human urine for 6 weeks, a few of white floaters of mixed PLA drug-eluting scaffold materials could be found and its weight were decreased by 15%. Under the SEM, the small holes were found on the surface of specimens. Finally, the materialsdegraded into samples similar to sediment after 10 weeks. Meanwhile, a few of floaters and degradation products similar to sediment of the PGLC drug-eluting scaffold materials, respectively, could be seen in all centrifuge tube after 4 weeks and 8 weeks.3. The drug loading of mixed PLA drug-eluting scaffold materialsdetected by HPLC were as follows.The drug loading of 6W group (1278?g±88?g) was significantly lower than that of 4W group (362?g±36?g)(.P<0.05).The drug loading of 8W group and 10W group were(780?g±32?g) and(362?g±36?g), respectively,which were significantly lower than that of the former groups (P<0.01).The drug loading of PGLC drug-eluting scaffold materialsdetected by HPLC were as follows.The drug loading dosage of the scaffolds were gradually decreased, and there were statistical difference between every two groups (P<0.01), except it between 0W group (1412?g±28?g)and 2W group (1335?g±74?g) (P>0.05).A further comparison of the drug loading of two types of rapamycin-eluting scaffold materials at the same time point indicated the drug loading of PGLC drug-eluting scaffold materials was lower than mixed drug-eluting scaffold materials at 4 weeks,6 weeks,8 weeks, with statistical differences(P<0.01).4. The results of histology showed that the acute inflammatory reactions of two types drug-eluting scaffold materials were mild and fibroustissue hyperplasia was proliferated slightly.Conclusion1. Two new types of biodegradable ureteral rapamycin-eluting scaffold materials were Successful constructed.2.The degradation and drug release property of PGLC drug-eluting scaffold materials were faster than mixed PLA drug-eluting scaffold materials.2. The degradation characteristics, drug release property and histocompatibility of two types biodegradable ureteral drug-eluting stent both could meet the requirements of the repair of human ureteral injury.