OBJECTIVE: To explore the possibility to bridge peripheral nerve defects by xenogeneic acellular nerve basal lamina scaffolds. METHODS: Thirty SD rats were randomly divided into 5 groups; in each group, the left sciatic nerves were bridged respectively by predegenerated or fresh xenogeneic acellular nerve basal lamina scaffolds, autogenous nerve grafting, fresh xenogeneic nerve grafting or without bridging. Two kinds of acellular nerve basal lamina scaffolds, extracted by 3% Triton X-100 and 4% deoxycholate sodium from either fresh rabbit tibial nerves or predegenerated ones for 2 weeks, were transplanted to bridge 15 mm rat sciatic nerve gaps. Six months after the grafting, the recovery of function was evaluated by gait analysis, pinch test, morphological and morphometric analysis. RESULTS: The sciatic nerve function indexes (SFI) were -30.7% +/- 6.8% in rats treated with xenogeneic acellular nerve, -36.2% +/- 9.7% with xenogeneic predegenerated acellular nerve, and -33.9% +/- 11.3% with autograft respectively (P gt; 0.05). The number of regenerative myelinated axons, diameter of myelinated fibers and thickness of myelin sheath in acellular xenograft were satisfactory when compared with that in autograft. Regenerated microfascicles distributed in the center of degenerated and acellular nerve group. The regenerated nerve fibers had normal morphological and structural characters under transmission electron microscope. The number and diameter of myelinated fibers in degenerated accellular nerve group was similar to that of autograft group (P gt; 0.05). Whereas the thickness of myelin sheath in degenerated accellular nerve group was significantly less than that of autograft group (P lt; 0.05). CONCLUSION: The above results indicate that xenogeneic acellular nerve basal lamina scaffolds extracted by chemical procedure can be successfully used to repair nerve defects without any immunosuppressants.
Fetal nerve grafts preserved at deep breezing were used to repair the peripheral nerve defects. The nerve directs included the sural nerves (removed as the donor nerve in repairing other nerve defects) in 5 cases, and digital nerve in 2 cases. All of them got good sensitive function. Patients were followed up for 1 yeas, all patients had gained comparatively good sensation. The surgical technique was introduced, and the validity of the transplantation of fetal nerve was discussed.
To observe the effect of allogenic transplantation of deep frozen nerve in repairing sensory nerve defect, 22 patients who had received this type of treatment were followed up for 0.5-5 years. There were 18 males and 4 females in this group, and the average age was 28 years old. Thirty-six nerve defects including the common volar digital nerve, proper volar digital nerve were repaired by allograft of nerves stored at deep frozen (-80 degrees C). The storation period was ranged from 9 days to 1 years. The length of the nerves were 2 cm-12 cm. After follow-up for 3 years (ranged from 7 months-5 years), 23 cases of nerve allograft obtained excellent and good results (63.9%), 10 cases were fair (27.7%) and 3 cases were poor (8.3%). It was concluded that (1) frozen nerve is one of nice materials for repairing the nerve defect (lt; 5 cm); (2) the immunity of allogenenic nerve is weak; (3) the deep frozen storation can reduce the immunity of nerve; (4) the dimethyl sulfoxide can prevent the nerve tissue from injury by deep frozen; (5) the best temperature and period for deep frozen storation should be studied further.
To find new technique for repair of peripheral nerve defect, the nerve elongation repair technique was adopted. Two cases with nerve defect were treated by this method. One was a 12 year old male, the defect length of right radial nerve was 7.2 cm at the elbow. The other one was a 28 year old male, the defect length of left ulnar nerve the was 5 cm at elbow. In this method, the nerve was elongated by slow stretch from distal and proximal end of the ruptured nerve. After a few days, the nerve was repaired by direct suture. After operation, the function of nerves were recovered in 119 days and 114 days respectively. Follow-up for 5 years, the function of the effected limbs were recovered to the normal side. It was concluded that: (1) the peripheral never can be elongated by slow stretch; (2) to stretch the nerve end in a rubber tube can prevent adhesion and connective tissue blocking; (3) strength and supporting point of stretching should be designed carefully.
ObjectiveTo fabricate salidroside/collagen/polycaprolactone (PCL) nerve conduit composite and to investigate the effect of composite nerve conduits for repairing sciatic nerve defect. MethodsThe salidroside microspheres were prepared by W/O/W method, and the sustained release rate of microspheres was detected. The microspheres containing 10, 20, and 40 μg salidroside were mixed with collagen to prepare the nerve conduit core layer by freeze-drying method. The shell layer of collagen/PCL scaffold material was fabricated by electrospinning technology. The genipin cross-linked salidroside/collagen/PCL nerve conduit composite was prepared. The structure of nerve conduit was observed before and after cross-linked by scanning electron microscope. Thirty-eight Wistar rats were used to make the right sciatic nerve defect model of 15 mm in length, and randomly divided into groups A, B, C, D (n=9), and group E (n=2), then defect was repaired with the collagen/PCL conduit in group A, autologous nerve in group E, the 10, 20, and 40 μg/mL salidroside/collagen/PCL conduit in groups B, C, and D, respectively. The survival of rats was observed. The sciatic functional index (SFI) was evaluated at 1, 3, and 6 months after operation. At 6 months, the tissue of defect area was harvested for the general, electrophysiology, histological, and immunohistochemical[S-100 and peripheral myelin protein 0(P0)] staining observations. ResultsSalidroside microspheres showed burst release at 3 days, and then it tended to be stable at 13 days and lasted for 16 days, with a cumulative release rate of 76.59%. SEM showed that the disordered fiber of nerve conduit shell layer after crosslinking became conglutination, shrinkage, and density, and had void. The channels of core layer were clearly visible before and after crosslinking. The rats had no infection or death after operation. The SFI of group E was significantly higher than that of groups A, B, C, and D at 1, 3, and 6 months (P<0.05); it was significantly higher in groups B, C, and D than group A (P<0.05), but no significant difference was found among groups B, C, and D at 1 month (P>0.05); there was no significant difference in SFI among groups A, B, C, and D at 3 months (P>0.05); SFI was significantly higher in group C than groups A, B, and D and in groups A and B than group D (P<0.05), but no significant difference between groups A and B (P>0.05) at 6 months. In addition, no significant difference was shown among different time points in the other groups (P>0.05) except groups C and E at 1, 3, and 6 months (P<0.05). The general observation showed that good connection with the thick nerve in groups B and C, and connection with the fine nerves in groups A and D. The conduit materials obviously degraded. Nerve electrophysiological examination showed that the latency/conduction velocity of groups C and E were significantly lower than those of groups A, B, and D (P<0.05), but difference was not significant between groups C and E, and among groups A, B, and D (P>0.05). The histological observation showed that the nerve fiber tissue of groups B, C, and E was obviously more than that of groups A and D, and group C was similar to group E in the nerve fiber arrangement, and the core layer material of each group was completely degraded. Immunohistochemical staining showed that S-100 and P0 proteins expressed in all groups; and the expression level of groups B, C, and E was significantly higher than that of groups A and D, and gradually increased (P<0.05); difference in S-100 expression level was not significant between groups A and D (P>0.05), and P0 expression level of group A was significantly lower than that of group D (P<0.05). ConclusionSalidroside/collagen/PCL nerve conduit can promote sciatic nerve defect repair.
Ten, fifteen and twenty millimeter nerve defects were produced on both trunks of sciatic nerve in 18 rabbits. The stumps of the nerve were enclosed by a silicon tube in the right hind limb (slilcon group) and the left limbs were free (free group). The proximal and distal nerve stumps in both groups were elongated by using a selfdesigned nerve stretching device, and the nerve were gradually stretched by 1mm, 2mm and 3mm per day respectively. when the expected lengths were achieved, the defects of the nerve were managed by endtoend coaptation. The samples were analysed by electrophysiological examination, and light and electron microscopes. Results were as follows: (1) The nerve defect could be repaired by gradual elongation in rabbits; (2) The results of silicon group were superior to the free group; (3) The structure and microcirculation of the nerve would be damaged if the stretching speed exceeded the limit of 2mm per day. But the eventual results following repair by elongation could not reached the normal level.
Objective To know the possibility of nerveregeneration after artery sleeve anastomosis and end-to-side suture Methods Seventy-five SD rats were divided into 5 groups. First, the distal end ofsevered peroneal nerve was sutured end-to -side with artery sleeve anastomosis withnormal nerve tibial trunk in groups A, B, C and D. Second, the tibial epineurium at the suture site was not removed in group A; the epineurium at the suturesite was removed(windowing) in group B; the distal end of pre-injured peroneal nerve was sutured after 14 days and windowing was done in group C; and the neural growth factor was injected into artery sleeve and windowing was done in group D. While the distal end of severed peroneal nerve was sutured end to side directly with normal nerve tibial trunk and windowing was done in group E. The histological observation was made and the number of nerve fibers was recorded after 4, 8 and 12 weeks of operation.Results After 4 weeks, there existed the regeneration of axons and myeline sheaths in groups C, D, E, and no nerve fiber regeneration was seen in group A. After 8 weeks, the regenerating nerve fibers were significantly more in groups C, D and E than in group B and ingroup E than groups C and D(Plt;0.05). After 12 weeks, the regenerating nervefibers were significantly more in groups C，D and E than in group B(Plt;0.05).Conclusion End-to-side coaptation with artery sleeve anastomosis is a new valuable method in repair of peripheral nerve injuries.
Objective To observe the revascularization process of transplanted nerve after transplantation of long nerve and accompanying peri pheral vessels, to investigate its relationship with nerve regeneration. Methods The mediannerve defect models of the left forelimb (3 cm in length) were made in 60 New Zealand rabbits (aged 6-8 months, weighing 2.0-2.5 kg, and male or female), which were randomly divided into 2 groups (n=30). In situ anastomosis of the median nerves was performed in the control group; in situ anastomosis of the median nerves was made in parallel to the surrounding elbow veins, the transplanted epineurium and the adventitia were sutured with nerve anastomosis l ine in the experimental group. After operation, the gross observation, electrophysiological testing, and histopathology observation was performed at 1, 2, 4, 8, and 12 weeks, and transmission electron microscope at 12 weeks to observe the revascularization of nerve grafts, nerve fiber regeneration, and functional recovery. Results In the experimental group, revascularization was observed at 1 week after operation, and the degree of revascularization was significantly higher than that in the control group at 2, 4, 8, and 12 weeks. At 8 and 12 weeks, the nerve fiber regeneration speed, quality, and quantity in the experimental group were better than those in the control group. At 2, 4, 8, and 12 weeks, the nerve conduction velocities were (10.32 ± 0.94), (13.14 ± 1.22), (22.68 ± 1.16), and (24.09 ± 1.27) m/ s respectively in the experimental group, and were (9.18 ± 1.07), (11.12 ± 1.03), (19.81 ± 1.37), and (20.67 ± 1.19) m/s in the control group, showing significant difference at 12 weeks after operation (t=3.167, P=0.001). At 12 weeks in the experimental group, the myel in sheath had similar size, less sheath plate delamination, normal Schwann cells and rich organelles, in which normal microfilaments, microtubules and axonal mitochondria were observed; axonal mitochondria had clear crestfilm and no swelling and vacuolization, and the neurofibrils basically became normal. The myelinated nerve fibers area, myelin thickness, and axon diameter were (5.93 ± 0.94) mm2, (0.72 ± 0.12) μm, and (3.12 ± 0.12) μm respectively in the experimental group, and were (5.28 ± 0.72) mm2, (0.65 ± 0.09) μm, and (2.98 ± 0.16) μm respectively in the control group, all showing significant differences (t=3.736, P=0.002; t=3.271, P=0.002; t=4.533, P=0.001). Conclusion The transplanted nerves in parallel to large blood vessels can promote angiogenesis of the transplanted nerve, and accelerate the regeneration and functional recovery of the nerves.
Objective To investigate the time l imit of repairing old sciatic nerve defect in rats and observe the repair effect of autogenous nerve transplantation on old sciatic nerve defect in rats. Methods Thirty-six SD rats of clean grade wererandomized into 6 groups (n=6 per group). The animal model of nerve defect was made by transecting left sciatic nerve at the mid-thigh level. For groups A1, B1 and C1, defects were repaired by the contralateral autogenous nerve transplantation 1, 3 or 6 months after nerve damage and for the control groups of A2, B2 and C2, defects were not repaired. After operation, the gait, toe skin and leg muscle were examined weekly. Three months after autograft, a combination of electrophysiology examination, fluoro gold (FG) retrograde tracing and histological assessment including l ight microscopy, TEM was util ized to investigate the nerve functional recovery. Results Lameness and foot skin ulcers were observed in each group after nerve damage. At 2 months after autograft, such denervation symptoms were only improved in groups A1 and B1. At 3 months after autograft, the motor conduction velocity was (21.84 ± 6.74), (20.02 ± 4.17) and (16.09 ± 8.21) m/s in groups A1, B1 and C1, respectively, showing no statistically significant difference between them (P gt; 0.05). The ampl itude of compound muscle action potential (CAMP) was (12.68 ± 4.38), (9.20 ± 3.43) and (1.22 ± 0.39) mV in groups A1, B1 and C1, respectively, indicating significant differences between groups A1, B1 and group C1 (P lt; 0.05). No CAMP was evident in groups A2, B2 and C2. FG retrograde tracing conducted 3 months after autograft showed that the positive cells were most common in group A1 with big soma, mild in group B1 and lest in group C1 with smallest soma. Gastrocnemius Masson staining showed that the fiber morphology of gastrocnemius in groups A1 and B1 was close to normal, while the rest 4 groups had an obvious atrophy of muscle fiber. The fiber cross-section area was (340.73 ± 118.46), (299.88 ± 119.75), (54.33 ± 53.43), (78.60 ± 51.38), (65.62 ± 25.36), and (40.93 ± 28.22) μm2 in groups A1, B1, C1, A2, B2 and C2, respectively, indicating a significant difference between groups A1, B1 and groups C1, A2, B2 (P lt; 0.05). Neurohistology observation showed that more regenerated nerve fibers were observed in group A1 and B1, but less in group C1. The myel in sheath was thick in groups A1 and B1, while it was thin in group C1. Only SCs and hyperplastic collagen fiber were found in groups A2, B2 and C2. Conclusion Autogenous nerve transplantation is capable of repairing 1- and 3- month sciatic nerve defect to some degree in rat, but repair effect is not obvious on 6-month sciatic nerve defect in rats.