Biocompatibility of two binds of poly (DL-lactide-co-glycolide)conduits with different copolymer ratio of lactide
- VernacularTitle:共聚比不同的两种聚乳酸-聚羟基乙酸共聚物材料生物相容性观测
- Author:
Wenjie ZHANG
;
Yue ZHOU
;
Jianzhong WANG
- Publication Type:Journal Article
- From:
Chinese Journal of Tissue Engineering Research
2005;9(46):148-150
- CountryChina
- Language:Chinese
-
Abstract:
BACKGROUND: Recently, α-hydroxy-acid and aliphatic series polyester synthetized with its derivates such as polylactide and polyglycolide have been studied extensively for scaffold of peripheral nerve tissue engineering.These materials might improve the effect of nerve guidance through overcoming several shortcomings of autografts, including permanent denervation of donor site, tissue deficiency, and potential differences in tissue structure and size.OBJECTIVE: To investigate the biocompatibility of poly (DL-lactide-coglycolide) (PLGA). Copolymer ratio of lactide: glycolide was 85:15 or 50:50)and evaluate its effect on nerve guidance.DESIGN: A comparative study and observation.SETTING: Department of Orthopaedics, Xinqiao Hospital of Third Military Medical University of Chinese PLA.MATERIALS: A total of 66 Wistar rats of either sex and clean grade,weighting 180-200 g, were involved; the 85:15 or 50:50 copolymer of poly (lactide-co-glycolde) (PLGA).METHODS: The experiment was carried out in Field Surgery Institute No. 6; State Key Laboratory of Trauma, Burns and Compound Injury, Daping Hospital of Third Military Medical University, from November 2001 to December 2002. ① Co-culture of Schwann cells with PLGA film: Growth of Schwann cells co-cultured with PLGA film was observed under scanning electron microscope. ② Histological observation of PLGA film: Fifteen Wistar rats were randomly divided into five groups (according to 1, 2, 4, 8and 12 weeks time point postoperatively) with 3 rats in each group. PLGA was trimmed to pieces of film with the size of 10.0 mm × 5.0 mm × 0.3 mmand implanted into the rat dorsal muscles under aseptic condition. Hematoxylin/eosin staining was used to evaluate inflammatory reaction. ③Bridging of sciatic nerve defect in rats with PLGA conduits: Fifty-one Wistar rats were divided into PLGA (85:15) conduit group, PLGA (50:50) conduit group and silicone conduit group, each of which was further divided into 5 subgroups according to different time points (2, 4, 6, 8, and 12weeks postoperatively) with 3 rats in each subgroup, except for 12-week time point subgroup which used 5 rats. Gross observation and electrophysiological studies (only 12 weeks time point postoperatively) were performed.The midconduit regenerated nerves were removed and then stained with toluidine blue. Histological observation of regenerated nerves was performed under the optical microscope.MAIN OUTCOME MEASURES: Primary outcome: ① Histological observation of PLGA film implanted in rat muscles. ② Electrophysiological and morphological evaluation of nerve guidance effect of PLGA conduits.Secondary outcome: Growth behavior of Schwann cells when co-cultured with PLGA films.RESULTS: All the 66 rats entered the result analysis. ① Histological observation of PLGA film implanted in rat muscles: The PLGA implants caused only minimal non-specific inflammatory reaction at an early time,as characterized by a low concentration of lymphocytes and fibroblasts,which was not present 10-12 weeks postoperatively. ② Cell attachment and morphological observation by scanning election microscopy: Schwann cells grew and proliferated well when co-cultured with PLGA film. ③Bridging of sciatic nerve defect in rats with PLGA conduits: Gross observation: Silicone induced significant proliferation of fibre tissues, characterized by encapsulation, when bridging sciatic nerve defects in rats, but the similar response could not be seen in PLGA in the same situation. At week 12 after bridging sciatic nerve defects in rats, motor nerve conduction velocity in PLGA (85:15) group was 17.03±0.66 m/s; it was 17.15±0.76 m/sin silicone group, with no significant difference between the two groups (P ＞ 0.05). Quantitative evaluation of regenerated nerves in PLGA group showed that the thickness of myelin sheath was (0.45±0.16) μm, fiber width was (3.96±1.73) μm, axon/mm2 10 135±1 053, and area percentage of neural tissues (%) was 23.4±2.7; in silicone group the corresponding data were (0.45±0.19) μm, (4.07±1.86) μm, (9879±1491) mm2 and (23.6±3.1)%, respectively, and there was no significant difference between the two groups (P ＞ 0.05). Since PLGA (50:50) conduit collapsed at an early time in the same animal model, corresponding indexes couldnot be detected in PLGA (50:50) group.CONCLUSION: In contrast to PLGA (50:50) and silicone, PLGA (85:15)is a good material for peripheral nerve tissue engineering because of its good biocompatibility and proper biodegradation rate.
