Muscle recovery after repair of short and long peripheral nerve gaps using fibrin conduits

Several lines of experimental evidence support an association between facial processing and social cognition, but no direct link between cortical markers of facial processing and complex cognitive processes has been reported until now. In the current study, we tested the hypothesis that cortical electrophysiological markers for the processing of facial emotion are associated with individual differences in executive and social cognition skills. We tested for correlations between the amplitude of event-related potentials (N170) in a dual valence task and participants’ scores on three neuropsychological assessments (general neuropsychology, executive functioning, and social cognition). N170 was modulated by the stimulus type (face versus word) and the valence of faces (positive versus negative). The neural source of N170 was estimated to be the fusiform gyrus. Robust correlations were found between neuropsychological markers and measures of facial processing. Social cognition skills (as measured by three tests: the Reading the Mind in the Eyes test, the Faux Pas test, and the Iowa Gambling Task) correlated with cortical measures of emotional discrimination. Executive functioning ability also correlated with the cortical discrimination of complex emotional stimuli. Our findings suggest that the cortical processing of facial emotional expression is associated with social cognition skills.     

组织工程化神经导管修复外周神经损伤

背景：神经导管技术理论上采用生物或非生物材料预制成合适的管状支架,桥接神经断端两侧,在提供神经再生微环境的同时通过神经诱导、营养作用促进神经再生。 目的：观察组织工程化神经导管修复外周神经损伤的临床效果。 方法：选择24例陈旧性上肢神经损伤患者,以患者自愿原则分2组治疗：试验组采用组织工程化神经导管修复,对照组采用自体周围体表感觉神经移植修复。治疗后随访6个月观察患者肢体神经损伤功能修复效果。 结果与结论：随访6个月后,两组肢体远端感觉运动功能与目测类比疼痛评分均较治疗前改善(P < 0.05),且试验组效果更好(P < 0.05);两组损伤侧感觉与运动神经传导速度均较治疗前改善(P < 0.05),且两组间差异无显著性意义。说明组织工程化神经导管材料符合神经修复导管支架的要求,临床应用疗效肯定。     

In vivo studies of silk based gold nano-composite conduits for functional peripheral nerve regeneration

We report a novel silk-gold nanocomposite based nerve conduit successfully tested in a neurotmesis grade sciatic nerve injury model in rats over a period of eighteen months. The conduit was fabricated by adsorbing gold nanoparticles onto silk fibres and transforming them into a nanocomposite sheet by electrospinning which is finally given a tubular structure by rolling on a stainless steel mandrel of chosen diameter. The conduits were found to promote adhesion and proliferation of Schwann cells in vitro and did not elicit any toxic or immunogenic responses in vivo. We also report for the first time, the monitoring of muscular regeneration post nerve conduit implantation by recording motor unit potentials (MUPs) through needle electromyogram. Pre-seeding the conduits with Schwann cells enhanced myelination of the regenerated tissue. Histo-morphometric and electrophysiological studies proved that the nanocomposite based conduits pre-seeded with Schwann cells performed best in terms of structural and functional regeneration of severed sciatic nerves. The near normal values of nerve conduction velocity (50 m/sec), compound muscle action potential (29.7 mV) and motor unit potential (133 μV) exhibited by the animals implanted with Schwann cell loaded nerve conduits in the present study are superior to those observed in previous reports with synthetic materials as well as collagen based nerve conduits. Animals in this group were also able to perform complex locomotory activities like stretching and jumping with excellent sciatic function index (SFI) and led a normal life.     

Fibrin conduit supplemented with human mesenchymal stem cells and immunosuppressive treatment enhances regeneration after peripheral nerve injury

To address the need for the development of bioengineered replacement of a nerve graft, a novel two component fibrin glue conduit was combined with human mesenchymal stem cells (MSC) and immunosupressive treatment with cyclosporine A. The effects of MSC on axonal regeneration in the conduit and reaction of activated macrophages were investigated using sciatic nerve injury model. A 10mm gap in the sciatic nerve of a rat was created and repaired either with fibrin glue conduit containing diluted fibrin matrix or fibrin glue conduit containing fibrin matrix with MSC at concentration of 80×10(6) cells/ml. Cells were labeled with PKH26 prior to transplantation. The animals received daily injections of cyclosporine A. After 3 weeks the distance of regeneration and area occupied by regenerating axons and ED1 positives macrophages was measured. MSC survived in the conduit and enhanced axonal regeneration only when transplantation was combined with cyclosporine A treatment. Moreover, addition of cyclosporine A to the conduits with transplanted MSC significantly reduced the ED1 macrophage reaction.     

合成可生物降解神经导管修复损伤周围神经：生物相容性良好

背景：临床对周围神经损伤进行修复治疗的时候,可以利用自体神经进行治疗或者利用不同材质的神经导管进行治疗。 目的：探索合成可生物降解材料神经导管在周围神经损伤修复中的应用效果。 方法：48只新西兰大白兔,随机等分为3组,自体神经移植组、硅胶导管组和可降解神经导管组。各组动物切除10 mm坐骨神经,构建坐骨神经缺损动物模型,并分别利用自体神经、硅胶导管以及可降解神经导管进行坐骨神经修复。 结果与结论：造模后3周,硅胶导管组兔运动神经传导效果、小腿三头肌肌肉湿质量恢复率比自体神经移植组差,但可降解神经导管组兔运动神经传导效果、小腿三头肌肌肉湿质量恢复率与自体神经移植组接近。造模后12周时,自体神经移植组中存在大量呈均匀排列的有髓神经纤维,可降解神经导管组中可见大量分布不均匀的再生有髓神经纤维,而硅胶导管组中存在少量呈不均匀排列的髓神经纤维。表明合成可生物降解材料神经导管在周围神经损伤修复中可以获得与自体神经较为接近的良好效果。  中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Comparison and characterization of multiple biomaterial conduits for peripheral nerve repair

Four biomaterial tubes, poly(lactic-co-glycolic acid) (PLGA), poly(caprolactone fumarate) (PCLF), a neutral oligo[(polyethylene glycol) fumarate] (OPF) hydrogel or a positively charged oligo[(polyethylene glycol) fumarate] (OPF⁺) hydrogel with a PCLF sleeve, have previously been shown to have benefits for nerve repair. However, no direct comparison to identify the optimal material have been made. Herein, these nerve tubes were implanted in a rat sciatic nerve model and nerve regeneration was quantified and compared by using accepted nerve assessment techniques. Using standard statistical methods, no significant differences of individual parameters were apparent between groups despite PCLF showing a tendency to perform better than the others. Using a mean–variance based ranking system of multiple independent parameters, statistical differences became apparent. It was clear that the PLCF tube supported significantly improved nerve regeneration and recovery compared to the other three biomaterial conduits. The ability to simultaneously compare a number of regenerative parameters and elucidate the best material from the combination of these individual parameters is of importance to the nerve regeneration area and has implications for the tissue engineering field. By using this method of comparison, a number of biomaterial constructs may be compared under similar conditions and the optimal construct elucidated using the minimal number of animals and materials.     

Loss of primary afferent nerve terminals in the brainstem after peripheral nerve transection: an anatomical study in monkeys

 In order to investigate the changes in the somatosensory organization that occur after a peripheral nerve injury, a purely sensory nerve (radial nerve – superficial branch) was divided in adult monkeys (Macaca fascicularis). The nerve ends were immediately rejoined by an epineural suturing technique. After 6–21 months the nerve investigated was exposed to an intra-axonal nerve tracer (horseradish peroxidase conjugate) in order to label the primary afferent terminals within the cuneate nucleus of the brainstem. The non-transected nerve on the contralateral side was similarly exposed and served as a control. Terminal labelling was seen throughout the cuneate nucleus, mainly in the middle of its rostro-caudal extension, and in this part it showed a patchy appearance superimposed on cell clusters within the pars rotunda. This pattern of distribution was seen both on the experimental and control sides. On the experimental side there was an obvious loss of terminal labelling within the terminal field as estimated using an image-analysing system: Compared with the contralateral side the median loss (peroxidase activity) was 83% and between 6 and 21 months only minor restoration of the terminal intensity was observed. These results in the primate confirm earlier results in the cat that transection and microsurgical repair of a sensory nerve causes a considerable loss of neurons capable of intraaxonal transport. Accepted: 14 April 1997     

Observation and measurements of long thoracic nerve: a cadaver study and clinical consideration

Long thoracic nerve (LTN) is an important nerve originating from cervical nerve roots. It varies a lot in origins and branches, which lead to several clinical problems, such as diagnosis, prophylaxis and treatment of LTN injury. LTN was dissected in 38 cadavers in the present study. Origin, level of union, branches, sites where nerve entered the muscle, length of nerve trunk and branches as well as transverse diameter were documented. Different derivations of LTN were observed, and C4-7, C5-7, C5 and C7, C5-7, C5-8, C6 and C7, and branch from C6 was the most important components of LTN. After evolution, LTN trunk was composed by superior and inferior trunks at scalenus muscle or the three superior slips level. Branches of LTN traveled on the surface of the six superior slips of anterior serratus muscle and then penetrated through the inferior slips without correlation between different branches. Mean length of trunk of LTN is 111.73 (30.08) mm, axis of cross section was 2.27 × 0.96 mm at the union level and 1.91 × 0.68 mm at the end branch. Each slip was innervated by 1–4 branches of LTN. The observation and measurement data described in our study presented some variations and could provide clinicians with important information on diagnosis, prophylaxis and treatment of LTN injury and pursuing more suitable muscle flaps for reconstruction operation.     

小鼠神经缺损管式修复后长时程功能恢复与再生评价

目的了解壳聚糖/聚乳酸-乙醇酸共聚体(PLGA)人工神经移植物修复小鼠神经缺损后神经功能长时程恢复水平与再生神经成熟度。方法采用人工神经移植物桥接修复小鼠坐骨神经缺损(n=6),以自体神经修复(n=6)和缺损组(n=6)为对照,术后1年采用热痛阈测定、电生理学、激光多普勒血流检测评定神经功能,采用靶肌湿重比、组织学和电子显微镜等技术综合评定神经重支配和再生神经成熟度。结果人工神经移植物组足底痛觉反应潜伏期、神经源性血管扩张程度、腓肠肌复合肌动作电位(CMAPs)波幅和潜伏期、靶肌湿重比、再生轴突数量等指标与自体神经修复组相近,但与健侧相比CMAPs潜伏期较长,髓鞘较薄,轴突直径分布滞后。结论人工神经移植物修复小鼠神经缺损术后1年感觉及自主神经功能、再生神经数量和靶肌重支配水平与自体神经修复相当,但再生神经纤维成熟度未达正常。     

A bioengineered peripheral nerve construct using aligned peptide amphiphile nanofibers

Peripheral nerve injuries can result in lifelong disability. Primary coaptation is the treatment of choice when the gap between transected nerve ends is short. Long nerve gaps seen in more complex injuries often require autologous nerve grafts or nerve conduits implemented into the repair. Nerve grafts, however, cause morbidity and functional loss at donor sites, which are limited in number. Nerve conduits, in turn, lack an internal scaffold to support and guide axonal regeneration, resulting in decreased efficacy over longer nerve gap lengths. By comparison, peptide amphiphiles (PAs) are molecules that can self-assemble into nanofibers, which can be aligned to mimic the native architecture of peripheral nerve. As such, they represent a potential substrate for use in a bioengineered nerve graft substitute. To examine this, we cultured Schwann cells with bioactive PAs (RGDS-PA, IKVAV-PA) to determine their ability to attach to and proliferate within the biomaterial. Next, we devised a PA construct for use in a peripheral nerve critical sized defect model. Rat sciatic nerve defects were created and reconstructed with autologous nerve, PLGA conduits filled with various forms of aligned PAs, or left unrepaired. Motor and sensory recovery were determined and compared among groups. Our results demonstrate that Schwann cells are able to adhere to and proliferate in aligned PA gels, with greater efficacy in bioactive PAs compared to the backbone-PA alone. In vivo testing revealed recovery of motor and sensory function in animals treated with conduit/PA constructs comparable to animals treated with autologous nerve grafts. Functional recovery in conduit/PA and autologous graft groups was significantly faster than in animals treated with empty PLGA conduits. Histological examinations also demonstrated increased axonal and Schwann cell regeneration within the reconstructed nerve gap in animals treated with conduit/PA constructs. These results indicate that PA nanofibers may represent a promising biomaterial for use in bioengineered peripheral nerve repair.     

Electrical stimulation of paralyzed vibrissal muscles reduces endplate reinnervation and does not promote motor recovery after facial nerve repair in rats

The outcome of peripheral nerve injuries requiring surgical repair is poor. Recent work has suggested that electrical stimulation (ES) of denervated muscles could be beneficial. Here we tested whether ES has a positive influence on functional recovery after injury and surgical repair of the facial nerve. Outcomes at 2 months were compared to animals receiving sham stimulation (SS). Starting on the first day after end-to-end suture (facial–facial anastomosis), electrical stimulation (square 0.1 ms pulses at 5 Hz at an ex tempore established threshold amplitude of between 3.0 and 5.0 V) was delivered to the vibrissal muscles for 5 min a day, 3 times a week. Restoration of vibrissal motor performance following ES or SS was evaluated using the video-based motion analysis and correlated with the degree of collateral axonal branching at the lesion site, the number of motor endplates in the target musculature and the quality of their reinnervation, i.e. the degree of mono- versus poly-innervation. Neither protocol reduced collateral branching. ES did not improve functional outcome, but rather reduced the number of innervated motor endplates to approximately one-fifth of normal values and failed to reduce the proportion of poly-innervated motor endplates. We conclude that ES is not beneficial for recovery of whisker function after facial nerve repair in rats.     

Regenerative potential of silk conduits in repair of peripheral nerve injury in adult rats

Various attempts have been made to develop artificial conduits for nerve repair, but with limited success. We describe here conduits made from Bombyx mori regenerated silk protein, and containing luminal fibres of Spidrex^®, a silk-based biomaterial with properties similar to those of spider silk. Assessment in vitro demonstrated that Spidrex^® fibres support neurite outgrowth. For evaluation in vivo, silk conduits 10 mm in length and containing 0, 100, 200 or 300 luminal Spidrex^® fibres, were implanted to bridge an 8 mm gap in the rat sciatic nerve. At 4 weeks, conduits containing 200 luminal Spidrex^® fibres (PN200) supported 62% and 59% as much axon growth as autologous nerve graft controls at mid-conduit and distal nerve respectively. Furthermore, Spidrex^® conduits displayed similar Schwann cell support and macrophage response to controls. At 12 weeks, animals implanted with PN200 conduits showed similar numbers of myelinated axons (81%) to controls, similar gastrocnemius muscle innervation, and similar hindpaw stance assessed by Catwalk footprint analysis. Plantar skin innervation was 73% of that of controls. PN200 Spidrex^® conduits were also effective at bridging longer (11 and 13 mm) gaps. Our results show that Spidrex^® conduits promote excellent axonal regeneration and function recovery, and may have potential for clinical application.     

Chemical ablation of sensory afferents in the walking system of the cat abolishes the capacity for functional recovery after peripheral nerve lesions

Weakening the ankle extensor muscles of cats by denervation of the synergists of the medial gastrocnemius (MG) muscle results in transient increase in yield at the ankle during early stance. Recovery of ankle function occurs over a period of 1–2 weeks, is use-dependent, and is associated with increases in the strength of reflexes from MG group I muscle afferents and an increase in the magnitude of bursts in the MG muscles during stance. These observations have led to the hypothesis that feedback from large muscle afferents is necessary for functional recovery. In this investigation we have tested this hypothesis by examining functional recovery in animals treated with pyridoxine, a drug known to destroy large muscle afferents. In four adult animals we confirmed that pyridoxine abolished the group I-mediated tendon-tap reflex in the ankle extensor muscle, and subsequently found that group I afferents from MG were either destroyed or non-conducting. Immediately after pyridoxine treatment the animals showed severe locomotor dysfunction but all recovered significantly over a period of 1 or 2 months and showed only minor kinematics deficits at the time of the muscle denervations. In all four pyridoxine-treated animals, weakening of the ankle extensors by denervation of the synergists of the MG muscle resulted in a large increase in yield at the ankle that persisted almost unchanged for a month after the operation. The magnitude of burst activity in the MG muscle during early stance of the pyridoxine-treated animals either did not increase or increased only slightly after the denervation of synergists. These observations are consistent with the hypothesis that feedback from group I afferents is necessary for functional recovery in untreated animals. Electronic Publication     

Oxidized galectin-1 advances the functional recovery after peripheral nerve injury

Oxidized galectin-1 has been shown to promote axonal regeneration from transected-nerve sites in an in vitro dorsal root ganglion (DRG) explant model as well as in in vivo peripheral nerve axotomy models. The present study provides evidence that oxidized galectin-1 advances the restoration of nerve function after peripheral nerve injury. The sciatic nerve of adult rats was transected and the distal nerve was frozen after being sutured into a proximal site with four epineurial stitches. An osmotic pump delivered oxidized galectin-1 peripherally to the surgical site. Functional recovery was assessed by measurement of the degree of toe spread of the hind paw for 3 months after the sciatic nerve lesion. The recovery curves of toe spread in the test group showed a statistically significant improvement of functional recovery after day 21 by the application of oxidized recombinant human galectin-1 (rhGAL-1/Ox) compared to the control group. This functional recovery was supported by histological analysis performed by light microscopic examination. The regenerating myelinated fibers at the site 21 mm distal to the nerve-transected site were quantitatively examined at 100 days after the operation. The frequency distribution of myelinated fiber diameters showed that exogenous rhGAL-1/Ox increased the number and diameter of regenerating myelinated fibers; the number of medium-sized (6–11 μm in diameter) fibers increased significantly (P < 0.05). These results indicate that oxidized galectin-1 promotes the restoration of nerve function after peripheral nerve injury. Thus, rhGAL-1/Ox may be a factor for functional restoration of injured peripheral nerves.     

Development and evaluation of silk fibroin-based nerve grafts used for peripheral nerve regeneration

Silk fibroin (SF), derived from natural silk long used as a textile material, has recently become an important biomaterial for tissue engineering applications. We have previously reported on good in vitro biocompatibility of SF fibers with peripheral nerve tissues and cells. In the present study, we developed a novel biomimetic design of the SF-based nerve graft (SF graft) which was composed of a SF-nerve guidance conduit (NGC) inserted with oriented SF filaments. The SF-NGC prepared via well-established procedures exhibits an eggshell-like microstructure that is responsible for its superior mechanical and permeable properties beneficial to nerve regeneration. The SF graft was used for bridge implantation across a 10-mm long sciatic nerve defect in rats, and the outcome of peripheral nerve repair at 6 months post-implantation was evaluated by a combination of electrophysiological assessment, FluoroGold retrograde tracing and histological investigation. The examined functional and morphological parameters show that SF grafts could promote peripheral nerve regeneration with effects approaching those elicited by nerve autografts which are generally considered as the gold standard for treating large peripheral nerve defects, thus raising a potential possibility of using these newly developed nerve grafts as a promising alternative to nerve autografts.     

Function and structure of atypical muscle spindles after neonatal nerve crush in rats

Summary During the early postnatal period, the differentiation and maturation of muscle spindles in the rat is still dependent on their sensory innervation. When a nerve is crushed during this period, most spindles in the denervated muscles degenerate and after reinnervation only occasional spindles of atypical structure are to be found in these muscles. We determined the basic functional properties of these atypical spindles in adult rats and attempted to correlate them with their structural characteristics. The discharge rates of 13 afferent units from the soleus or lateral gastrocnemius muscles were evaluated in response to stretch. These units were capable of a slowly adapting response to 2–4 mm stretches. Their mean discharge frequencies at any point of the ramp-and-hold stretch were, however, on an average 50% lower than normal values. The conduction velocities of afferents from the atypical spindles were in the range of 10–40 m/s. Histological examinations revealed that 90% of the atypical muscle spindles found in the soleus or lateral gastrocnemius muscles had only 1 or 2 intrafusal fibres without any nuclear accumulations as compared to four intrafusal fibres in normal muscle spindles in the rat. The proportional decrease of the discharge rate in both the dynamic and static part of the response of these atypical spindles could be due to the decreased synaptic area between the sensory terminals and the intrafusal fibres and/or to altered structural properties of the intrafusal fibres.     

Altered expression of nectin-like adhesion molecules in the peripheral nerve after sciatic nerve transection

Following axotomy several processes involving cell-cell interaction occur, such as loss of synapses, axon guidance, and remyelination. Two recently discovered families of cell-cell adhesion molecules, nectins and nectin-like molecules (necls) are involved in such processes in vitro and during development, but their roles in nerve injury have been largely unknown until recently. We have previously shown that axotomized motoneurons increase their expression of nectin-1 and nectin-3 and maintain a high expression of necl-1. We here investigate the expression of potential binding partners for motoneuron nectins and necls in the injured peripheral nerve. In situ hybridization (ISH) revealed a decreased signal for necl-1 mRNA in the injured nerve, whereas no signal for necl-2 was detected before or after injury. The signals for necl-4 and necl-5 mRNA both increased in the injured nerve and necl immunoreactivity displayed a close relation to axon and Schwann cell markers. Finally, signal for mRNA encoding necl-5 increased in axotomized spinal motoneurons. We conclude that peripheral axotomy results in altered expression of several necls in motoneurons and Schwann cells, suggesting involvement of the molecules in regeneration.     

可降解神经套接管制备及临床试验流程专家共识

周围神经损伤是一种常见临床疾病,损伤后的有效修复是减少损伤并发症、改善预后的重要措施.临床上治疗单纯横断伤或微小缺损的神经损伤多采用显微外科对位缝合方式吻合神经断端,但临床修复效果难达到预期.基于周围神经选择性再生学说,研究者发现小间隙套接缝合的修复效果明显好于传统的神经外膜缝合方法.因此,研发一种用来桥接周围神经断端...     

低照度激光辐射周围神经组织损伤修复的研究进展

周围神经损伤修复是神经组织损伤康复研究领域中的一项重要课题.目前,周围神经损伤治疗的新技术很多,随着激光对生物作用机制研究的发展,低照度激光辐射周围神经组织损伤修复作为一种新的组织再生方法被应用到神经损伤修复领域.主要围绕弱激光照射神经组织修复机制以及周围神经损伤后功能恢复和神经组织部位瘢痕抑制进行论述,并对激光照射神经损伤治疗和修复的新进展作一综述.     

Ginsenoside Rg1 promotes peripheral nerve regeneration in rat model of nerve crush injury

Searching for effective drugs which are capable of promoting nerve regeneration after nerve injuries has gained extensive attention. Ginsenoside Rg1 (GRg1) is one of the bioactive compounds extracted from ginseng. GRg1 has been shown to be neuroprotective in many in vitro studies, which raises the possibility of using GRg1 as a neuroprotective agent after nerve injuries. However, such a possibility has never been tested in in vivo studies. The present study was designed to investigate the efficacy of GRg1 in promoting nerve regeneration after nerve crush injury in rats. All rats were randomly divided into four groups (n = 8 in each group) after crush injury and were intraperitoneally administrated daily for 4 weeks with 1 mg/kg, or 5 mg/kg GRg1 (low or high dose GRg1 groups), or 100 μg/kg mecobalamin or normal saline, respectively. The axonal regeneration was investigated by retrograde labeling and morphometric analysis. The motor functional recovery was evaluated by electrophysiological studies, behavioral tests and histological appearance of the target muscles. Our data showed that high dose GRg1 achieved better axonal regeneration and functional recovery than those achieved by low dose GRg1 and mecobalamin. The final outcome of low dose GRg1 and mecobalamin was similar in both morphological and functional items, which was significantly better than that in saline group. These findings show that GRg1 is capable of promoting nerve regeneration after nerve injuries, suggesting the possibility of developing GRg1 a neuroprotective drug for peripheral nerve repair applications.