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.
ObjectiveTo evaluate the long-term effects on the lower limb function after S1 nerve root transection as dynamic source. MethodsBetween January 2007 and December 2011, 47 patients with atonic bladder dysfunction underwent S1 nerve root transposition to reconstrut the bladder function. There were 43 males and 4 females, with an average age of 40.7 years (range, 22-66 years). The locations were LS1 in 33 cases, LS2 in 5 cases, LS3 in 2 cases, TS12, LS1 in 3 cases, LS1, LS2 in 1 case, LS1, LS3 in 1 case, LS1, LS4 in 1 case, and LS2, LS3 in 1 case. The anastomosis of the SS2 or SS3 nerve root to S1 nerve root was performed from 4 to 24 months (mean, 8 months) after spinal cord injury. The strength of ankle plantar flexion was grade 4 in 5 cases and grade 5 in 42 cases before operation. ResultsThe strength of ankle plantar flexion had no obvious decrease (grade 4 or 5) in 31 cases, reduced 0.5 grade in 16 cases at 2 days after operation. All the patients were followed up 3-8 years (mean, 5.1 years). At 2 weeks after operation, the nerve electrophysiological examination showed neurogenic damage at operated side in most patients, including reduced amplitude tibial nerve in 19 cases, for common peroneal nerve in 13 cases, and for tibial nerve and common peroneal nerve in 9 cases. Except the velocity of common peroneal nerve (t=-1.881, P=0.093), the other electric physiological indexes showed significant differences between at pre- and post-operation (P<0.05). The muscle strength basically recovered to preoperative level (grade 4 or 5) during follow-up, and there was no impairment of lower limb function. ConclusionS1 transection has no significant effects on lower limb function, so S1 nerve can be used as dynamic nerve for nerve function reconstruction.
ObjectiveTo investigate the regularity of myelin degeneration and regeneration and the difference of axonal density between tibial nerve and common peroneal nerve after sciatic nerve injury repair in rhesue monkey. MethodsNine adult rhesue monkeys (male or female, weighing 3.5-4.5 kg) were selected to establish the model of rat sciatic nerve transaction injury. The tibial nerve and common peroneal nerve of 5 mm in length were harvested at 5 mm from injury site as controls in 3 monkeys; the distal tibial nerve and common peroneal nerve were repaired with 9-0 suture immediately in the other 6 monkeys. And the gross observation and neural electrophysiological examination were performed at 3 and 8 weeks after repair respectively. Then, distal tibial nerve and common peroneal nerve at anastomotic site were harvested to observe the myelin sheath changes, and to calculate the number of axon counts and axonal density by staining with Luxol Fast Blue. ResultsAtrophy of the lower limb muscle and various degrees of plantar ulcer were observed. Gross observation showed nerve enlargement at anastomosis site, the peripheral connective tissue hyperplasia, and obvious adhesion. The compound muscle action potential (CMAP) of tibial nerve and common peroneal nerve could not be detected at 3 weeks; the CMAP amplitude of common peroneal nerve was less than that of the tibial nerve at 8 weeks. Different degrees of axonal degeneration was shown in the tibial nerve and common peroneal nerve, especially in the common peroneal nerve. The average axonal density of common peroneal nerve was lower than that of tibial nerve at 3 weeks (13.2% vs. 44.5%) and at 8 weeks (10.3% vs. 35.3%) after repair. ConclusionThe regeneration of tibial nerve is better and faster than that of common peroneal nerve, and gastrocnemius muscle CMAP recovers quicker, and amplitude is higher, which is the reason of better recovery of tibial nerve.