Application of transforming growth factor-beta 1 plasmid in local host during frozen nerve allograft / 中国组织工程研究

ABSTRACT

BACKGROUND: In repair of nerve defect with allogenic nerve graft, to reduce immune rejection is one of the key problems. At present, the main approach is to reduce antigenicity of grafted nerve segment and apply generally immune inhibitor.OBJECTIVE: To observe the effects of freeze/thaw treatment and local application of transforming growth factor beta 1 (TGF-β1) plasmid on frozen nerve allograft.DESIGN: Randomized controlled animal experiment was designed.SETTING: Department of Hand Surgery, Union Hospital, Tongji Medical College Affiliated to Huazhong University of Science and Technology.MATERIALS The experiment was performed in Tongji Medical College of Huazhong University of Science and Technology from January 2003 to December 2004, in which 40 Wistar healthy and adult rats were employed,from different delivery and were randomized into experimental group and control, 20 rats in each one.METHODS: Transforming growth factor-β1 (TGF-β1) plasmid and frozen allogenic sciatic nerve were prepared. In experimental group and control,sciatic nerve was cut off 2.0 cm in length, in the foramen 0.5 cm beneath piriformis. The nerve defect was repaired with pre-frozen allogenic nerve 2.0 cm in length. In experimental group, TGF-β1 plasmid was injected in local muscle and two broken ends of nerve. In the control group, physiological saline of equal volume was injected. In the 6th and 12th weeks, the samples were collected from 10 rats in each group for sectioning, staining,axonal counting and statistical analysis.RESULTS: No any animal was died in experiment and all of animals entered result analysis. In the 6th weeks, in the control group, mild edema appeared among axons on the grafted segment of nerve and in the experimental group, there was no edema among axons and the regenerated nerve numbers were close to the normal. In the 12th week, in the experimental group, the entire grafted nerve segment was basically filled up by the regenerated axons;myelinated nerve fiber was arranged in order and both axons and myelins were developed well. The regenerated axonal count in experimental group was more significantly than the control, indicating extremely significant difference [(98.6±4.8), (75.8±5.1) counts/μm2, t=2.962, P ＜ 0.01].CONCLUSION: Freeze/thaw treatment can decrease antigenicity of allogenic nerve, which provides the possibility of repair of nerve defect. Local application of TGF-β1 plasmid can provide immune inhibition locally and reduce immune rejection in the host.