Repairing sciatic nerve crush injury by transplantation of bone marrow mesenchymal stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND: Bone marrow mesenchymal stem cells (BMSCs) are conveniently cultured and separated in vitro because theirimmunogenicity is low. Therefore, BMSCs are suitable for cell transplantation. Research has shown that BMSCs are potential to repair neurological defect. OBJECTIVE: To determine whether in vitro cultured BMSCs can be transplanted to repair peripheral nerve injury or not, and to investigate its mechanisms. DESIGN, TIME AND SETTING: Randomized controlled animal study This study was performed in Department of Toxicology, Public Health College of Jilin University from March 2006 to March 2007.MATERIALS Fifty healthy female Wistar rats aging 2 months and six 1-week-old female Wistar rats were used for extraction of BMSCs. Rabbit-anti-nerve growth factor (NGF) monoclonal antibody was provided by Santa Cruz Company. METHODS:BMSCs were separated and cultured with adherent method. In the 3rd generation, BMSCs were preiabeled with bromodeoxyuridine (BrdU) 48 hours before transplantation. Fifty healthy Wistar rats were selected to prepare sciatic nerve crush injury models with clamping method.Subsequently, rats were randomly divided into transplantation group and control group, with 25 rats in each group. Rats in the transplantation group underwent transplantation of BrdU-labeied BMSCs at nerve injured sites; while, the same volume DMEM was injected into rats in the control group. MAIN OUTCOME MEASURES: Injured nerve in the transplantation group suffered from anti-BrdU staining 1, 2, 4, and 6 weeks after surgery. Distal injured nerve in both groups suffered from NGF immunohistochemical staining 1, 2, 4, and 6 weeks after surgery. Image analysis system was adopted to analyze integrated absorbance of positive expression. Gait analysis was performed every week after surgery to measure sciatic nerve function index, and it was also adopted to measure regenerated nerve conduction velocity 6 weeks after surgery. Subsequently, amount and inner diameter of medullated nerve fibers were calculated after luxol fast blue staining, while wet weight of experimental-lateral gastrocnemius muscle and cross section area of muscle fiber were measured at the same time. RESULTS: Fifty rats were included in the final analysis. BrdU-labeled positive cells could be found at injured nerve in the transplantation group 1, 2, and 4 weeks after surgery. Integrated absorbance of NGF protein expression in the transplantation group was significantly higher than that in the control group 1 and 2 weeks after surgery (P < 0.01), but there were no significant differences between the two groups 4 and 6 weeks after surgery (P > 0.05). Sciatic nerve function index in the transplantation group superiorly recovered to that in the control group 3-6 weeks after surgery. Furthermore, 6 weeks after surgery, nerve conduction velocity, amount and diameter of medullated nerve fibers, wet weight and cross section area of gastrocnemius muscle in the transplantation group were significantly higher than those in the control group (P < 0.05-0.01). CONCLUSION: BMSCs can be transplantated into injuried nerve tissue, and promote the recovery of nerve function in the micro-enviroment, improve NGF expression in an early phase may be one of its mechanisms.