Functional nerve recovery after bridging a 15 mm gap in rat sciatic nerve with a biodegradable nerve guide

Recovery of nerve function was evaluated after bridging a 15?mm sciatic nerve gap in 51 rats with a biodegradable poly(DL-lactide-ε-caprolactone) nerve guide. Recovery of function was investigated by analysing the footprints, by analysing video recordings of gait, by electrically eliciting the withdrawal reflex, by nerve conduction velocity and by electromyography (EMG). Sensory nerve function recovered as measured by electrostimulation. Motor nerve function partly recovered but electromyograms remained abnormal throughout the study. We conclude that functional reinnervation by regenerating axons occurs after bridging a 15?mm nerve gap with a biodegradable poly(DL-lactide-ε-caprolactone) nerve guide, but the walking patterns remain abnormal. Video analysis is a useful tool to record and analyse the walking patterns of rats. Further studies are necessary to investigate the possibility of obtaining selective reinnervation of specific muscles.     

Functional assessment of sciatic nerve recovery: biodegradable poly (DLLA-epsilon-CL) nerve guide filled with fresh skeletal muscle

The aim of this study was to compare functional peripheral nerve recovery in the rat sciatic nerve model after reconstruction of a 10-mm gap with a biodegradable poly (DLLA-epsilon-CL) nerve guide, as filled with either fresh skeletal muscle or phosphate-buffered saline (PBS). During 24 weeks of recovery, motor and sensory functional evaluation was tested by extensor postural thrust (EPT) and withdrawal reflex latency (WRL), respectively. At the end of the experiment, anesthetized animals were prepared for motor nerve conduction velocity (MNCV) studies, followed by gastrocnemius and soleus muscle weight measurement. Motor functional recovery was greater in the muscle-grafted group, and reached a significant difference from weeks 8-12 (P < 0.05). The results of this investigation suggest that filling a nerve guide with fresh skeletal muscle induces faster maturation of regenerated nerve fibers in comparison with traditional tubular repair.     

Functional recovery after facial and sciatic nerve crush injury in the rat

OBJECTIVES: To systematically record rat facial nerve recovery following crush injury to the main trunk with respect to ocular and vibrissial function and to compare the rates of facial and sciatic nerve recovery from crush injury in the same animals. This serves as a means of validating the functional parameters of facial nerve recovery against the well-known measure of hind limb function, the Sciatic Function Index. METHODS: The main trunk of the facial nerve and the proximal segment of the sciatic nerve were exposed in all animals. Both nerves were subjected to standardized crush injury and subsequent daily functional testing. After a plateau of functional recovery was achieved, the animals were killed, and the distances between the sites of injury and the end musculature were measured, which allowed determination and comparison of recovery rates in both systems. RESULTS: All crush injuries resulted in loss of electrical conductivity, as proven by intraoperative proximal nerve stimulation. Recovery of ocular and vibrissial motor function occurred starting at postoperative day (POD) 9 and continuing through POD 20. Hind limb function returned later (POD 14-34); however, when corrected for distance, the sciatic recovery rate (2.26 mm/d) appeared to match that of the facial nerve (1.5-2.4 mm/d). CONCLUSIONS: Recovery after facial nerve crush injury follows a predictable time course, and the rate of recovery is consistent with that of sciatic nerve injury. Return of the blink reflex, loss of vibrissial fibrillations, and return of vibrissial sweeping function appear to be internally consistent functional measures of facial recovery. These quantitative measures will be useful for future facial nerve manipulation studies.     

Functional assessment after sciatic nerve injury in a rat model

The aim of this study is to evaluate the effectiveness of Sciatic Function Index (SFI) and Basso, Beattie, and Bresnahan (BBB) Locomotor Rating in assessing peripheral nerve injuries. SFI is a standard method for evaluating crush and transected peripheral nerve injuries, likewise BBB for spinal cord injury. Models of chronic nerve compression (CNC), crush, and transection injury were created on Sprague‐Dawley rats and functional outcomes were measured using BBB and SFI at 1‐week interval for 6 weeks. All injury models showed high correlation between SFI and BBB scores. With crush injury, the SFI showed near complete recovery while BBB showed residual deficits 6 weeks after injury. Both the BBB and SFI were unable to detect motor deficits in 6‐week CNC animals. The BBB score should be considered as an adjunct in evaluating peripheral nerve recovery and may be more sensitive in detecting residual deficits than SFI after crush‐type injuries. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.     

无细胞的异体神经修复鼠坐骨神经缺损

目的 通过化学萃取同种异体神经,去除髓鞘和雪旺细胞,形成无细胞基膜管后桥接鼠坐骨神经缺损,研究神经再生效果。方法 正常鼠坐骨神经用非变性生物剂处理后得到无细胞的基膜管,桥接鼠坐骨神经20mm缺损。实验分3组:无细胞基膜管移植组(A组),自体神经移植组(B组)和异体神经移植组(C组)。术后进行肌电图、光镜、电镜及图象分析仪检查。结果 A组再生神经有大量轴突通过移植体,术后2个月电生理检测再生神经的潜伏期及波幅低于B组(P<0.05),术后3个月2组差异无显著意义。髓鞘厚度在术后3个月时亦低于B组,差异有显著意义(P<0.05)。轴突直径及数目两组无差异。C组因无神经再生,结果无法测量。结论 这种无细胞基膜管移植体能支持轴突的生长和雪旺细胞的迁移,是一种良好的神经移植替代材料。     

Functional recovery following neurorrhaphy of the rat sciatic nerve by epineurial repair compared with tubulization

Recovery of motor function is often poor following transection injuries to peripheral nerves. The purpose of this study was to measure and compare functional recovery of the sciatic nerve in the rat following transection and neurorrhaphy with the use of a nerve guide tube and with traditional end-to-end epineurial repair. Muscle recovery was also evaluated following a crush injury, a model of an axonotmetic lesion. Recovery was assessed at 8, 16, and 32 weeks after injury by measuring the isometric contractile properties of the soleus muscle and at 8 and 16 weeks by measuring the conduction properties of the sciatic nerve. The mean conduction velocity of the sciatic nerve in the crush group and both transection groups was significantly slower than that of controls at both 8 and 16 weeks. Following a transection injury, the soleus became, significantly faster muscle as measured by time to peak twitch tension. By 32 weeks, the maximum isometric tension of the soleus muscle recovered to 90% that of the control group following a crush injury and to less than 70% following a trensection injury and repair. Recovery was better in the epineurial repair group than in the tube repair group at 8 weeks, but no difference was found between the groups at 16 or 32 weeks. These, results demonstrate that nerve guide tubes are a potential alternative to epineurial repair. The poor motor recovery following repair of transection injuries may be related to poor specificity of reinnervation.     

Bioartificial nerve graft for bridging extended nerve defects in rat sciatic nerve based on resorbable guiding filaments.

A long defect (15 mm) in rat sciatic nerve was repaired with a bioartificial nerve graft composed of a silicone tube and seven synthetic filaments of five types (polyamide, catgut, polydioxanone, and two types of polyglactin, normal and quickly-absorbed) inserted longitudinally into the tube. In all cases in which filaments were used a regenerating bridge was obtained in the tube after three months in contrast to empty silicone tubes, in which no structure was observed. There was a 6%-46% recovery of isometric muscle contractility of the anterior tibial and gastrocnemius muscles with positive pinch reflex test in most cases. Myelinated axons were seen in the regenerating tissue between the filaments but not directly in contact with them, and there were varying numbers of macrophages close to the filaments. Silicone tubes with filaments, regardless of type of filament, induced nerve tissue to regenerate and resulted in functional recovery through a 15 mm nerve gap not achieved with empty tubes. Nerve promoting factors may be applied to the filaments and the model is a valuable tool for further development of artificial nerve grafts.     

Functional recovery after repair of peroneal nerve gap using different collagen conduits

Background

Currently, autologous nerve implantation to bridge a long nerve gap presents the greatest regenerative performance in spite of substantial drawbacks. In this study, we evaluate the effect of two different collagen conduits bridging a peroneal nerve gap.

Methods

Rats were divided into four groups: (1) the gold standard group, in which a 10-mm-long nerve segment was cut, reversed, and reimplanted between the nerve stumps; (2) the CG-I/III group, in which a type I/III collagen conduit bridged the gap; (3) the CG-I, in which a type I collagen conduit was grafted; and (4) the sham group, in which a surgery was performed without injuring the nerve. Peroneal Functional Index and kinematics analysis of locomotion were performed weekly during the 12 weeks post-surgery. At the end of the protocol, additional electrophysiological tests, muscular weight measurements, axon counting, and g-ratio analysis were carried out.

Results

Functional loss followed by incomplete recovery was observed in animals grafted with collagen conduits. At 12 weeks post-surgery, the ventilatory rate of the CG-I group in response to exercise was similar to the sham group, contrary to the CG-I/III group. After KCl injections, an increase in metabosensitive afferent-fiber activity was recorded, but the response stayed incomplete for the collagen groups compared to the sham group. Furthermore, the CG-I group presented a higher number of axons and seemed to induce a greater axonal maturity compared to the CG-I/III group.

Conclusions

Our results suggest that the grafting of a type I collagen conduit may present slight better prospects than a type I/III collagen conduit.     

犬化学去细胞神经同种异体移植的实验研究

目的以化学去细胞同种坐骨神经移植修复犬坐骨神经的长段缺损，观察其功能恢复及神经再生。方法15犬分成去细胞同种神经组(实验组)6犬、自体神经组(对照组Ⅰ)6犬、新鲜同种神经组(对照组Ⅱ)3犬。右侧坐骨神经造成5．0cm长缺损，以上述三种移植物桥接修复。术后6个月行步态分析、神经电生理及神经再生观察。结果实验组和对照组Ⅰ在运动功能恢复，踝关节运动步态，小腿二头肌运动诱发电位、感觉诱发电位，移植段内新生轴突、血管及雪旺细胞，远端胫神经内有髓神经纤维及靶肌肉运动终板等方面非常相似。对照组Ⅱ神经功能始终无恢复，移植段被吸收。结论化学去细胞同种神经移植物修复犬粗大长段神经缺损时不会被宿主排斥和吸收，其近期功能恢复及神经再生与自体神经移植无明显差别。     

Long-term evaluation of nerve regeneration in a biodegradable nerve guide

Nerve regeneration using artificial biodegradable conduits is of increasing interest. The aim of this study is to evaluate the regeneration and maturation of a nerve after long-term implantation (2 years) of a biodegradable poly-L-lactide/poly-e-caprolactone (PLLA/PCL) copolymeric nerve guide in the sciatic nerve of the rat. After harvesting, we evaluated both the regenerated nerves and the controls, using light microscopy, transmission electron microscopy, and morphometric techniques. Remnants of biomaterial were still present after 2 years of implantation, but the foreign body reaction was very mild at this stage, due to the rounded shapes of the polymer debris. Morphometric analysis showed significant differences between the regenerated nerve and the normal sciatic nerve: the number of myelinated fibers is higher, and the mean fiber diameter of the myelinated fibers in the regenerated nerve is smaller. In conclusion, the results demonstrate that the new PLLA/PCL nerve guide can provide optimal conditions for regeneration and maturation of damaged nerves. © 1993 Wiley-Liss Inc.     

Functional recovery of sciatic nerve through inside-out vein graft in rats

Objective: Present study aimed at further comprehensive functional, histomorphometrical and immunohistochemical assessment of peripheral nerve regeneration using rat sciatic nerve transection model.Methods: The 10-mm rat sciatic nerve gap was created in rats. In control group nerve stumps were sutured to adjacent muscle and in treatment group the gap was bridged using an inside-out vein graft. In sham-operated group the nerve was manipulated and left intact. All animals underwent walking track analysis test 4, 8, and 12 weeks after surgery.Subsequently, muscle mass measurement was performed to assess reenervation, histological examination to observe the sciatic nerve regeneration morphologically and immunohistochemistry to detect Schwann cells using anti S-100. Results were analyzed using a factorial ANOVA with two between-subjects factors. Bonferroni test for pairwise comparisons was used to examine the effect of treatments.Results: Functional analysis ofmyelinated nerve fibers showed that nerve function improved significantly in the time course in treatment group. However, quantitative morphometrical analysis of myelinated nerve fibers showed that there was no significant difference between 8 and 12 weeks in treatment group. Muscle weight ratio was bigger and weight loss of the gastrocnemius muscle was ameliorated by inside-out vein grafting. The position of positive immunohistochemical reactions further implied that regenerated axons and Schwann cell-like cells existed after vein grafting was performed, and was accompanied by the process of myelination and structural recovery of regenerated nerves.Conclusion: Functional analysis of peripheral nerve repair is far more reliable than quantitative morphometrical analysis     

Isogenic venous graft supported with bone marrow stromal cells as a natural conduit for bridging a 20 mm nerve gap

In this study, we introduce a technique for bridging large neural gaps, using an isogenic vein graft supported with isogenic bone marrow stromal cells (BMSC). In three groups a nerve defect of 20 mm was bridged with a vein graft. Our first experimental group comprized an empty venous graft, in group II the venous nerve graft was filled with saline where as in group III the venous nerve graft was filled with BMSC. The animals were tested for functional recovery up to 3 months post repair. Our results show that the BMSC filled venous graft resulted in significantly better regeneration of the nerve defect compared to controls, as confirmed by the functional recovery measured by somatosensory evoked potentials, toe spread, pin prick, and gastrocnemius muscle index. Conclusively, the results confirm that the vein graft supported with BMSC is associated with better functional nerve regeneration. © 2010 Wiley‐Liss, Inc. Microsurgery, 2010.     

Nerve regeneration and functional recovery after a sciatic nerve gap is repaired by an acellular nerve allograft made through chemical extraction in canines

The purpose of the present study is to test whether chemically extracted acellular nerve segments can be used to repair the sciatic nerve gap. Fifteen canines were divided into acellular nerve allografting group (ANG, six canines), autografting group (AG, six canines), and fresh nerve allografting group (FNG, three canines). The sciatic nerves on the right side of the animals were exposed, and 5-cm-long segments of the nerves were removed from the midthigh level and replaced by the three types of grafts. At 6 months after grafting, all animals in the ANG and AG had similar patterns of right posterior limb gait cycle and right ankle movements. Moreover, the animals in the ANG and AG had similar nerve regeneration, with dense regeneration fibers in the distal tibial nerves and obvious motor end plates in the target muscle. But in FNG, the area surrounding the graft was scarred as the result of inflammation, and there was a brown central area where there was little nerve regeneration. All of the above shows that chemical acellular nerve allografting can be used to repair a gap as long as 5 cm in the continuity of the sciatic nerve in canines and has similar effects to autografting.     

Long-term evaluation of functional nerve recovery after reconstruction with a thin-walled biodegradable poly (DL-lactide-epsilon-caprolactone) nerve guide, using walking track analysis and electrostimulation tests.

This study was performed to evaluate the long-term functional nerve recovery after reconstruction of a 10-mm gap in the sciatic nerve of the rat, with a thin-walled nerve guide, composed of a biodegradable copolymer of DL-lactide and epsilon-caprolactone [p(DLLA-epsilon-CL)]. To evaluate both motor and sensory nerve recovery, walking track analysis and electrostimulation tests were carried out after implantation periods ranging from 3 to 52 weeks postoperatively. The first signs of both motor and sensory nerve recovery could be observed after 5 weeks. After 15 weeks, 70% of the sciatic function and 90% of the sensory nerve function had been recovered. After this period, the sciatic function index (SFI) did not improve further, whereas the sensory nerve function appeared to return to normal. When the results of the SFI measurements, minus those obtained from rats with severe automutilation, are extrapolated, further improvement of the SFI might be expected after 52 weeks. The fact that 100% sensory nerve recovery was obtained, as measured by the electrostimulation test, could be explained by sensory reinnervation from surrounding areas. The SFI was not fully reestablished because automutilation had a great impact on the use of walking track assessment.     

Detection of E-cadherin expression after nerve repair in a rat sciatic nerve model

After four nasal aesthetic functional surgeries in a period of 18 months, a 46-year-old woman was evaluated who presented with moderate functional alteration, saddle-nose deformity, and total loss of the septal cartilage. Four months before presentation the patient sustained severe nasal trauma, resulting in depression of the nasal bridge without loss of function. Her problem was diagnosed initially as a consequence of an infected septal hematoma and loss of the septal cartilage. Based on this diagnosis, the patient was subjected, in an 18-month period, to four reconstructive surgeries by different specialists, without any improvement and with worsening of clinical presentation. During the authors' physical examination of the patient, she demonstrated marked nasal cutaneous retraction, atrophic nasal conchae with total loss of the septal cartilage, and a large loss of septal bone. Three nasal mucosa biopsies were acquired and the authors proceeded to carry out complete nasal reconstruction using external cranial table and rib cartilage. Histopathologically, a lesion was noted that was compatible with angiocentric lymphoma, for which treatment was administered according to this type of illness. The authors point out the importance of establishing an adequate diagnosis in the face of an apparently obvious clinical case, present cross-disciplinary treatment, and discuss the study protocol that should be used for this type of pathology. They present their reconstructive technique of the nasal structure using a combination of bone tissue and cartilage, the results, and the current state of the patient.     

Functional assessment of sciatic nerve reconstruction: biodegradable poly (DLLA-epsilon-CL) nerve guides versus autologous nerve grafts

The aim of this study was to compare functional nerve recovery after reconstruction with a biodegradable p(DLLA-epsilon-CL) nerve guide filled with modified denatured muscle tissue (MDMT), or an autologous nerve graft. We evaluated nerve recovery using walking track analysis (measurement of the sciatic function index [SFI]) and electrostimulation tests. Functional nerve recovery after reconstruction with a biodegradable p(DLLA-epsilon-CL) nerve guide filled with MDMT was faster when compared with nerve reconstruction using an autologous nerve graft. We conclude that in case of a short nerve gap in the rat, reconstruction can best be carried out using a p(DLLA-epsilon-CL) biodegradable nerve guide filled with MDMT.     

甲壳质生物套管小间隙桥接大鼠周围神经的实验研究

目的探讨脱乙酰甲壳质生物套管小间隙桥接周围神经损伤的可行性。方法将120只SD大鼠右侧坐骨神经切断,按手术方法随机分为5组。A组:神经外膜原位缝合(n=24);B组:套管小间隙原位桥接(n=24,间隙5mm);C组:两断端相对旋转180°后外膜缝合(n=24);D组:两断端相对旋转180°后套管小间隙桥接(n=24,间隙5mm);E组:套管小间隙原位桥接(n=24,间隙5mm)后间隙内注射神经生长因子(NGF)。术后2、4、6、8周分别进行电生理学检查、组织学检查以及计算单位视野有髓神经纤维数。结果组织学检查术后4周各实验组的神经远端均见到再生的神经纤维;小间隙套管组(B,D组)运动神经传导速度在各个时间检测点上均好于相应的直接外膜缝合组(A组)和旋转后直接外膜缝合组(C组)(P<0·05)。小间隙套管组(B,D组)神经远端的有髓神经纤维计数在4、6、8周3个检测点上高于相应的直接外膜缝合组(A组)和旋转后直接外膜缝合组(C组)(P<0·01);在2周时差异没有统计学意义(P>0·05)。结论生物套管小间隙(5mm)桥接的修复周围神经的效果好于断端外膜直接缝合,具有替代直接神经外膜缝合的临床应用可行性。     

Nerve growth factor combined with an epineural conduit for bridging a short nerve gap (10 mm). A study in rabbits

The purpose of this study was to evaluate the effect of direct administration of nerve growth factor (NGF) into an epineural conduit across a short nerve gap (10 mm) in a rabbit sciatic nerve model. The animals were divided into two groups. In group 1, n = 6, a 10-mm defect was created in the sciatic nerve and bridged with an epineural flap. A dose of 1 μg of NGF was locally administered daily for the first 21 days. NGF administration was made inside the epineural flap using a silicone reservoir connected to a silicone tube. In group 2, n = 6, the 10-mm defect was bridged with a nerve graft. This group did not receive any further treatment. At 13 weeks, all animals, before euthanasia, underwent electromyography (EMG) studies and then specimen sent for histology morphometric analysis. NGF administration ensured a significantly increased average number of myelinated axons per μm(2) (P = 0.028) and promoted fiber maturation (P = 0.031) and better EMG results (P = 0.046 for latency P = 0.048 for amplitude), compared with the control group. Although nerve grafts remain the gold standard for peripheral nerve repair, NGF-treated epineural conduits represent a good alternative, particularly when an unfavorable environment for nerve grafts is present.     

Claudin 14/15 play important roles in early wallerian degeneration after rat sciatic nerve injury

PurposeWallerian degeneration (WD) is an antegrade degenerative process distal to peripheral nerve injury. Numerous genes are differentially regulated in response to the process. However, the underlying mechanism is unclear, especially the early response. We aimed at investigating the effects of sciatic nerve injury on WD via CLDN 14/15 interactions in vivo and in vitro.MethodsUsing the methods of molecular biology and bioinformatics analysis, we investigated the molecular mechanism by which claudin 14/15 participate in WD. Our previous study showed that claudins 14 and 15 trigger the early signal flow and pathway in damaged sciatic nerves. Here, we report the effects of the interaction between claudin 14 and claudin 15 on nerve degeneration and regeneration during early WD.ResultsIt was found that claudin 14/15 were upregulated in the sciatic nerve in WD. Claudin 14/15 promoted Schwann cell proliferation, migration and anti-apoptosis in vitro. PKCα, NT3, NF2, and bFGF were significantly upregulated in transfected Schwann cells. Moreover, the expression levels of the β-catenin, p-AKT/AKT, p-c-jun/c-jun, and p-ERK/ERK signaling pathways were also significantly altered.ConclusionClaudin 14/15 affect Schwann cell proliferation, migration, and anti-apoptosis via the β-catenin, p-AKT/AKT, p-c-jun/c-jun, and p-ERK/ERK pathways in vitro and in vivo. The results of this study may help elucidate the molecular mechanisms of the tight junction signaling pathway underlying peripheral nerve degeneration.