Effect of transforming growth factor beta-1 on regeneration of nerve after transplantation of fresh nerve allograft / 中国组织工程研究

ABSTRACT

BACKGROUND: Auto-neural transplantation is used widely on peripheral neurological defect, but it also has some difficulties. So some scholars try to use xenoma-neural transplantation; however, it is hard todeal with immunological rejection.OBJECTIVE: To study the effect of transforming growth factor-β1 (TGFβ1) used in local area on neural regeneration after transplantation of fresh nerve allograft.DESIGN: Randomized controlled study.SETTING: Hand Surgery Department of Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and TechnologY.MATERIALS The experiment was conducted in the Union Hospital Affiliated to Tongji Medical College of Huazhong University of Science and Technology between August 2001 and October 2002. Totally 60healthy adult Wistar rats from different confinements were randomly divided into three groups including experimental group, blank group and control group with 20 in each group.METHODS: TGF-β1 plasmid was prepared for using. Establishment of animal model Sciatic nerve at the 0.5 cm deep of piriformis muscle of rats in the two groups was cut with disinfectant razor into chip regularly about 2.0 cm. The excisional nerve segment was exchanged to transplant plerosis neurological defect. TGF-31 was injected into the local muscles and bisection of nerve in the experimental group, and equal volume of saline was injected into rats in the blank group and the control group. In addition, rats in the experimental group and the blank group were not treated with any drugs, but cyclosporine A (15 mg/kg) was used to feed rats in the control group. Ten rats from each group were taken for section and staining at the 6th and the 12th week ① Glees-luxot fast blue staining method; ② myelin sheath fast blue staining method. Axonal amount Fields were randomly taken from the middle staining samples 12 weeks later and 1.0 mm2 interaxis-cylinder was counted under light microscope of 400 times. Comparisons among groups were analyzed with i test.MAIN OUTCOME MEASURES: Morphological observation and axonal amount of transplanted area in each group.RESULTS: Quantitative analysis of the experimental animals Totally 60rats entered the final analysis without any loss. ① Infiltration of monocytes was observed widely in various areas of graft in the blank group;meanwhile, desiccation of myelin sheath and plenty of vacuolations were also observed, especially at the sixth week. The whole graft was infiltrated by monocyte with severe rejection. Few axis-cylinders were regenerated in the transplanted segment. At the 12th week, graft was slender, plenty of scar tissues were proliferated, edema was observed obviously, few Schwann cells and regenerated axis-cylinders were observed, and lots of regenerated axis-cylinders did not pass the whole graft. A few infiltrative monocytes were observed, and edema was observed obviously, but new vessel was formed in transplanted nerve, and regenerated axis-cylinders passed the whole graft in the experimental group and the control group.Lots of Schwann cells were observed at the 6th week; meanwhile, regenerated axis-cylinders passed the whole graft at the 12th week, a quantitative myelinization was formed, Schwann cells proliferated obviously, and edema between axis-cylinder was relieved. Numbers of peripherally regener ated axis-cylinder of nerve and remyelination in each ransplanted area were more than those in the central area, and edema between peripheral axis-cylinder was milder than that in the central area in the experimental group. ② Twelve weeks after operation, 5 rats in each group were selected to observe their fields, which were taken randomly from neural graft,under the microscope of 400 times to count 1.0 mm2 inter-axis-cylinders.Number of axis-cylinder was higher in the experimental group and the control group than that in the blank group, and the differences were significant [(78.3±4.6), (76.1±4.2) , (15.0±3.5) ,t=3.056, t=2.948, P ＜ 0.01];however, number in the experimental group was similar to that in the control group, and differences were not significant [(78.3±4.6), (76.1±4.2),t=1.982 P ＞ 0.05].CONCLUSION: TGF-β1 used in local area plays an immunosuppressive action locally, decreases host immunological rejection, increases the number of axis-cylinder, and accelerates growth of nerve.