Basing on the experimental results, 48 nerve defects (with the length of 3-4 cm in 21 cases, 4.1-5cm in 25 cases and 6cm in 2 cases) were repaired clinically by using vaseularized nerve sheath canal with living Schwann s cells, 87.5 percent of them obtained good results. The advantages were: (1) The neural sheath had rich blood supply with resultant less scar from its healing; (2) The living Schwann s cells would secrete somatomedin to promote the reproduction of neural tissues; and (3) The useless neurofib...
Objective To make a comparison between the effects of the small intestinal submucosa (SIS) graft and the insideout vein graft on repairing the peripheral nerve defects. Methods SIS was harvested from the fresh jejunum of the quarantined pig by curetting the musoca, the tunica serosa, and the myometrium; then, SIS was sterilized, dried and frozen before use. Thirty-six male SD rats were divided into 3 groups randomly, with 12 rats in each group. Firstly, the 10mm defects in the right sciatic nerves were madein the rats and were respectively repaired with the SIS graft (Group A), the insideout autologous vein graft (Group B), and the autonerve graft (Group C). At 6 weeks and 12 weeks after the operations, the right sciatic nerves were taken out, and the comparative evaluation was made on the repairing effects by the histological examination, the neural electrophysiological examination, the computerized imaging analysis, and the Trueblue retrograde fluorescence trace. Results The histological examination showed that the regenerated nerve fibers were seen across the defects in the three groups at 6 weeks after the operations. The nerve fibers were denser, the formed nerve myelin was more regular, and the fibrous tissue was less in Group A than in Group B; the nerve regeneration was more similar between Group A and Group C. At 12 weeks after the operations, the neural electrophysiological examination showed that the neural conductive rate was significantly lower in Group B than in Groups A and C (Plt;0.05),but no statistically significant difference was found between Group A and GroupC (Pgt;0.05); the component potential wave amplitude was not statistically different between Group A and Group B; however, the amplitude was significantly lower in Groups A and B than in Group C (Plt;0.05). At 6 weeks and 12 weeks after the operations, the computerized imaging analyses showed that the axiscylinder quantity per area and the nerve-tissue percentage were significantly greaterin Group A than in Group B (Plt;0.05); the average diameter of the regenerated axis cylinder, the axiscylinder quantity per area, and the nerve-tissue percentage were significantly lesser in Group B than in Group C (Plt;0.05). At 12 weeks after the operations, the Trueblue retrograde fluorescence trace revealed that the positivelylabeled neurons were found in the lumbar 3-6 dorsal root ganglion sections in the three groups. Conclusion The small intestinal submucosa graft is superior to the autologous inside-out vein graft in repairing the peripheral nerve defects and it is close to the autonerve graft in bridging the peripheral nerve defects. Therefore, the small intestinal submucosa is a promising biological material used to replace the autonerve graft.
A 0.6cm segment of right common peroneal nerve was resected in 60 SpragueDawley rats. The nerve defects were bridged by adhering the epineurium with autogenous nerve, vein, skeletal muscle, tendon and silastic tube. According to the kinds of the grafts used, the rats were divided into 5 groups. In 6 and 12 weeks after operation, the effect was assessed by motor nerve conduction velocity, weight of the anterior tibial muscle, number of distal axons and histological examination. It was demonstrated that the result from autogenous nerve graft was superior to other grafts in all aspects and that of the vein graft was better thanthe other three. The characteristics of the nerve regeneration and the process of maturation in different types of the grafts were discussed. The related microenvironment which caused the difference was also discussed.
ObjectiveTo summarize the applications of Schwann cells (SCs), stem cells, and genetically modified cells (GMCs) in repair of peripheral nerve defects. MethodsThe literature of original experimental study and clinical research related with SCs, stem cells, and GMCs was reviewed and analyzed. ResultsSCs play a key role in repair of peripheral nerve defects; the stem cells can be induced to differentiate into SCs, which can be implanted into nerve conduits to promote the repair of peripheral nerve defect; genetically modified technology can enhance the function of SCs and different stem cells, which has been regarded as a new option for tissue engineered nerve. ConclusionAlthough great progress has been made in tissue engineered nerve recently, mostly limited to the experimental stage. The research of seed cells in application of tissue engineered nerve need be studied deeply.
ObjectiveTo summarize the research progress of autologous vein nerve conduit for the repair of peripheral nerve defect. MethodsThe recent domestic and foreign literature concerning autologous vein nerve conduit for repair of peripheral nerve defect was analyzed and summarized. ResultsA large number of basic researches and clinical applications show that the effect of autologous venous nerve conduit is close to that of autologous nerve transplantation in repairing short nerve defect, especially the compound nerve conduit has a variety of autologous nerve tissue, cells, and growth factors, etc. ConclusionAutologous vein nerve conduit for repair of non-nerve defect can be a good supplement of autologous nerve graft, improvement of autologous venous catheter to repair peripheral nerve defect is the research direction in the future.
Objective To investigate the promotion effect of neurotropic reinnervation with chemically extracted acellular nerve allograft. Methods The sciatic nerves of 5 healthy adult SD rats, regardless of gender and weighing 270-300 g, were collected to prepare chemically extracted acellular nerve allograft. Eighteen healthy adult Wistar rats, regardless of genderand weighing 300-320 g, were made the model of left sciatic nerve defect (10 mm) and randomly divided into 2 groups: autograft (control group, n=9) and allograft group (experimental group, n=9). The defects were bridged by acellular nerve allograft in experimental group and by autograft by turning over the proximal and distal ends of the nerve in control group. At 3 months after transplantation, dorsal root ganglion (DRG) resection operation was performed in 6 rats of 2 groups. At 3 weeks after operation, the sural nerves were harvested to calculate the misdirection rate of nerve fibers with pathological staining and compute-assisted image analysis. Cholinesterase staining and carbonic anhydrase staining were performed in the sural nerve of 3 rats that did not undergo DRG resection at 3 months. Results The results of chol inesterase staining and carbonic anhydrase staining showed that experimental group had less brown granules and more black granules than control group. After DRG resection, count of myelinated nerve fiber were 4 257 ± 285 in the experimental group and 4 494 ± 310 in the control group significant (P lt; 0.05). The misdirection rate was 2.27% ± 0.28% and 7.65% ± 0.68% in the experimental group and in the control group respectively, showing significant difference (P lt; 0.05). Conclusion Chemically extracted acellular nerve allograft can not only act as a scaffold in the period of nerve defects repair, but markedly enhance the effects of neurotropic reinnervation.
ObjectiveTo study the effect of the loaded concentration gradient of nerve growth factor (NGF) immobilized conduit on rat peripheral nerve defect repair. MethodsThe peripheral nerve conduits made of poly (ε-caprolactone)-block-poly (L-lactide-co-ε-caprolactone) were prepared with uniform loads or concentration gradient loads by combining differential absorption of NGF/silk fibroin (SF) coating, and the gradient of NGF was immobilized in the nerve conduits. ELISA method was used to exam the NGF release for 12 weeks in vitro. Twenty-four male Sprague Dawley rats (weighing, 220-250 g) were selected to establish the right sciatic nerve defect model (14 mm in length) and randomly divided into 4 groups according to repair methods. The transected nerve was bridged by a blank conduit without NGF in group A, by a conduit containing uniform loads of NGF in group B, by a conduit concentration gradient loads of NGF in group C, and by the autogenous nerve segment in group D. The gross observation, electrophysiological examination, histological observation, and transmission electron microscope observation were carried out to assess the nerve regeneration at 12 weeks after surgery. ResultsThe cumulative release amount of NGF was (14.2±1.4) ng/mg and (13.7±1.3) ng/mg in gradient of NGF loaded conduits and uniform NGF loaded conduits respectively at 12 weeks, showing no significant difference (t=0.564, P=0.570). All the animals survived to completion of the experiment; plantar ulcers occurred at 4 days, which healed at 12 weeks; groups C and D were better than groups A and B in ulcerative healing. At 12 weeks after surgery, the compound muscle action potential of group A was significantly lower than that of groups B, C, and D (P<0.05), and group B was significantly lower than groups C and D (P<0.05), but no significant difference was found between groups C and D (P>0.05). The axon density of group C was significantly higher that of groups A, B, and D (P<0.05); group D was significantly higher than groups A, B, and C, and group C was significantly higher than groups A and B in the axon number, axon diameter, and area of muscle fiber (P<0.05); the thickness of myelin sheath of groups C and D was significantly larger than that of groups A and B (P<0.05), but no significant difference was found between groups C and D (P>0.05). ConclusionGradient of NGF loaded nerve condnits for rat sciatic nerve defect has similar results to autogenous nerve, with a good bridge, which can promote the sciatic nerve regeneration, improve the myelinization of the regenerating nerve, and accelerate the function reconstruction of the regenerating nerve.
Objective To investigate the effect of the sciatic nerve elongation on pain in rats. Methods Thirty-six adult male Wistar rats of SPF grade, weighing 250-300 g. Eighteen of them were randomly divided into 3 groups, 6 rats in each group. They were sciatic nerve elongation group (group A), nerve no-elongation group (group B), and nerve ligation group (group C). The model of 10-mm sciatic nerve defect was established in all 3 groups. The sciatic nerve was extended at a speed of 1 mm/d for 14 days in group A. The group B was only installed with external fixation. The nerve stumps were ligated in the group C. At 3, 7, 10, and 14 days after operation, the foot injury was evaluated by the autotomy scoring scale. At 14 days after operation, the dorsal root ganglia (DRG) of L4-S1 spinal cord of rats in each group was observed by tumor necrosis factor α (TNF-α) immunohistochemical staining, and the primary antibodies were replaced by pure serum as negative control group. Another 18 rats were randomly divided into 3 groups, 6 rats in each group. They were sciatic nerve elongation group (group A1), nerve no-elongation group (group B1), positive control group (group C1). In groups A1 and B1, the 10-mm long sciatic nerve defect model was established by the same method as groups A and B, and then fixed with external fixation. Nerve elongation was done or not done without anesthesia at 3 days after operation. In group C1, no modeling was done and 20 μL 2.5% formaldehyde was injected into the toes. After 90 minutes, the dorsal horn of spinal cord of L4-S1 segment of rats was cutting for c-Fos immunohistochemical staining and the number of positive cells was counted. Primary antibodies were replaced with pure serum as negative control group. Results The autotomy scores of rats in groups B and C gradually increased postoperatively, and group A remained stable at 0.25±0.50. The scores of group C were significantly higher than those of group A and group B at each time point postoperatively (P<0.05). The scores of group A were significantly lower than those of group B at 10 and 14 days postoperatively (P<0.05). TNF-α immunohistochemical staining showed that the TNF-α expression in group A was weak, slightly positive (+/-); in group B was positive (+); in group C was strongly positive (++); and the negative control group had no TNF-α expression (-). c-Fos immunohistochemical staining showed that the c-Fos expressions in groups A1 and B1 were weak positive, in group C1 was strong positive, and negative control group had no c-Fos positive expression. The number of c-Fos positive cells in groups A1, B1, C1, and negative control group were (21.5±6.6), (19.3±8.1), (95.6±7.4), and 0 cells/field, respectively, and group C1 was significantly higher than groups A1 and B1 (P<0.05), there was no significant difference between group A1 and group B1 (P>0.05). Conclusion Nerve elongation does not cause obvious pain neither during the operation of elongation nor throughout the whole elongation.
OBJECTIVE To explore the effect of basic fibroblast growth factor (bFGF) combined with autogenous vein graft conduit on peripheral nerve regeneration. METHODS Fifty four New Zealand rabbits were divided into three groups. The main trunk of sciatic nerve of rabbit in one side was severed and bridged by autogenous vein. 0.2 ml bFGF solution (4,000 U/ml) was intravenously injected to the vein graft conduit as group A, the same amount of saline solution as group B, and no solution injection as group C. Microscopic examination, axon video analysis and nerve conduct velocity were performed at the 10th, 30th, and 100th day after operation. RESULTS The nerve fibers were grown into vein graft conduit in all groups at 30th after operation, they were more and regular in group A than that of group B and C, and the axon regeneration rate in group A was more than that of group B and C. CONCLUSION bFGF combined with autogenous vein graft conduit can markedly promote nerve regeneration.
ObjectiveTo investigate the effect of electrospun chitosan/polylactic acid (ch/PLA) nerve conduit for repairing peripheral nerve defect in rats. MethodsNerve conducts loaded with ch/PLA was made by the way of electrospun. The mechanical property, hydrophility, biocompatibility were tested, and the scanning electron microscope was used to observe the ultrastructure. The same experiments were also performed on pure PLA nerve conducts as a comparison. Then, 54 Sprague Dawley rats were divided into 3 groups randomly, 18 rats in each group. Firstly, the 10 mm defects in the right sciatic nerves were made in the rats and were respectively repaired with ch/PLA (group A), autografts (group B), and no implant (group C). At 4, 8, and 12 weeks after operation, general observations, sciatic functional index (SFI), electrophysiological evaluation, wet weight of gastrocnemius and soleus muscles, histological examination, immunohistological analysis, and transmission electron microscopy were performed to evaluate the effects. ResultsCompared with pure PLA nerve conducts, the addition of chitosan could improve the mechanical property, hydrophility, biocompatibility, and ultrastructure of the nerve conducts. At 4 weeks postoperatively, the regenerated nerve bridged the nerve defect in group A. The SFI improved gradually in both group A and group B, showing no significant difference (P>0.05). Compound muscle action potentials and nerve conduction velocity could be detected in both group A and group B at 8 and 12 weeks after operation, and significant improvements were shown in both groups (P<0.05). The wet weight and myocyte cross section of gastrocnemius and soleus muscles showed no significant difference between group A and group B (P>0.05), but there was significant difference when compared with group C (P<0.05) at 12 weeks postoperatively. Immunohistological analysis revealed that S-100 positive Schwann cells migrated in both group A and group B, and axon also regenerated by immunohistological staining for growth associated protein 43 and neurofilaments 160. Transmission electron microscopy showed no significant difference in the diameter of nerve fiber between group A and group B (P>0.05), but the thickness of myelin sheath in group A was significantly larger than that in group B (P<0.05). ConclusionThe electrospun ch/PLA nerve conduits can effectively promote the peripheral nerve regeneration, and may promise an alternative to nerve autograft for repairing peripheral nerve defect.