骨骼肌卫星细胞异体移植对周围神经缺损后再生的影响

背景：有研究表明肌卫星细胞不仅在体外具有较强的增殖能力及适应能力,而且在异体内免疫原性低,免疫排斥反应低,移植后存活时间长。因此设想肌卫星细胞异体移植在促进缺损神经再生等方面可能具有良好的研究和应用前景。 目的：探讨骨骼肌卫星细胞移植对周围神经缺损后再生修复的影响。 方法：将16只Wistar大鼠随机分成移植组与对照组,每组8只,均切断右后肢坐骨神经,并通过生物可降解膜包裹缺损神经断端形成神经再生室。用微量注射器抽取已配制成的肌干细胞悬液0.2 mL注入移植组的神经再生室内。对照组注入等量的生理盐水。术后4,8和12周进行大鼠行步态测定,并用锇酸染色法制片观察缺损神经再生情况。观测大鼠坐骨神经功能指数、腓肠肌湿质量恢复率、再生的有髓神经纤维数量和直径及髓鞘厚度的变化。 结果与结论：大鼠经肌卫星细胞移植后腓肠肌湿质量残存率、再生的有髓神经纤维数目、直径及髓鞘厚度等项检测指标与对照组相比均差异有显著性意义(P < 0.05)。术后8和12周,移植组坐骨神经功能指数恢复情况明显优于对照组(P < 0.05)。实验结果提示在神经再生室中加入肌卫星细胞能促进缺损神经纤维的再生及其结构的成熟。 关键词：肌卫星细胞;生物可降解膜;异体;细胞移植;周围神经缺损;神经再生     

1102/异种神经脱细胞移植物桥接大鼠坐骨神经缺损

目的　探讨异种神经脱细胞移植物桥接大鼠坐骨神经缺损后的神经再生及其再生过程中免疫排斥反应。 方法　用脱细胞兔周围神经作为移植物桥接大鼠坐骨神经1cm缺损;术后3、5、8、11、15天检测血液中淋巴细胞占白细胞百分比;3个月后取移植物及腓肠肌,用甲苯胺蓝、乙酰胆碱酯酶(AchE)、琥珀酸脱氢酶(SDH)组化染色,光、电镜观察神经再生及腓肠肌运动终板的恢复情况。　 结果　术后大鼠血液中淋巴细胞占白细胞的百分比与正常大鼠相比较无显著性差异,3个月后大鼠术侧下肢足趾能分开,行走时后蹬动作有力,针刺足底有逃避反应,桥接物内见有大量再生的坐骨神经纤维,腓肠肌肌纤维上见有呈AchE阳性的运动终板和神经纤维。　 结论　异种神经脱细胞移植物桥接大鼠坐骨神经缺损具有促进其再生的作用。     

重组腺病毒载体AxCA-BDNF基因转染修复坐骨神经损伤*☆

背景：如何促进周围神经损伤修复与再生一直是基础与临床研究的热点。基因治疗有可能成为今后解决该问题的主要手段之一。 目的：观察携带小鼠脑源性神经营养因子(brain-derived neurotrophic factor,BDNF) cDNA表达片段的重组腺病毒载体AxCA-BDNF转染大鼠损伤坐骨神经后BDNF的表达,以及脊髓前角运动神经元的存活和神经生长情况。 方法：切除成年Wistar大鼠股中部10 mm长的坐骨神经,AxCA-BDNF转染组、BDNF组和对照组分别用硅胶管内置AxCA-BDNF原液,BDNF溶液或空白病毒稀释液桥接坐骨神经两断端。术后3,7,14 d,1,2,4个月应用原位杂交和免疫组织化学方法检测损伤坐骨神经及相应脊髓节段BDNF mRNA和蛋白的表达,并观察损伤坐骨神经的组织学及超微结构改变,再生的神经元及有髓神经纤维数目和髓鞘厚度。 结果与结论：术后3,7,14 d及1个月时,AxCA-BDNF转染组损伤坐骨神经近、远端神经干及脊髓(L3~6)中BDNF mRNA和蛋白水平明显高于BDNF组和对照组(P < 0.01)。光、电镜病理组织学检查和图像分析证实,BDNF基因转染后,脊髓前角运动神经元存活数量、新生神经纤维数目及其髓鞘厚度、神经联接的再形成均明显优于对照组(P < 0.01)。说明经腺病毒介导转染的BDNF基因可在大鼠坐骨神经内有效表达,并通过轴突逆行转运到了相应的脊髓神经元,不仅能促进损伤神经纤维再生,也能保护损伤的脊髓神经元。 关键词：坐骨神经损伤;重组腺病毒;脑源性神经营养因子;基因转染;免疫组织化学;原位分子杂交;神经再生     

维拉帕米与神经生长因子促进大鼠坐骨神经再生的协同作用

背景：实验证明周围神经损伤时,轴突的变性与神经元凋亡都与Ca2+的超载有着极其密切的关系。 目的：利用大鼠坐骨神经损伤模型观察L型钙离子通道阻滞剂维拉帕米联合神经生长因子促进周围神经再生的协同作用。 设计、时间及地点：随机对照动物实验,于2007-04/2008-11在辽宁医学院手外科实验室完成。 材料：同系健康雄性SD大鼠32只,体质量220~260 g;维拉帕米为辽宁卫星制药厂产品,国药准字H21022847;神经生长因子为sigma公司产品。 方法：同系SD大鼠32只随机分为4组,每组8只,分别在右侧梨状肌下缘5 mm切断坐骨神经后立即原位缝合造成坐骨神经损伤模型。①维拉帕米+神经生长因子组：腹腔注射维拉帕米4 mg/(kg•d),术侧腓肠肌肉注射神经生长因子0.6 μg/d。②维拉帕米组：腹腔注射维拉帕米4 mg/(kg•d),术侧腓肠肌注射等量生理盐水。③神经生长因子组：术侧腓肠肌注神经生长因子0.6 μg/d,并腹腔注射等量生理盐水。④空白对照组：分别腹腔,肌注等量生理盐水。以左侧坐骨神经为正常对照。 主要观察指标：术后12周对各组再生神经进行大体观察,神经电生理测定,组织学观察及有髓神经纤维计数。 结果：术后12周,维拉帕米+神经生长因子组足部溃疡的出现与愈合以及展抓反射出现的时间均早于其他各组。神经传导速度恢复率和有髓神经纤维计数恢复率分析表明：维拉帕米+神经生长因子组>维拉帕米组>神经生长因子组>空白对照组。光镜和电镜下可见：维拉帕米+神经生长因子组再生的神经纤维最多,轴突较为粗大。有髓神经纤维多,髓鞘完整,优于其他3组。神经纤维直径恢复率分析表明：维拉帕米+神经生长因子组>神经生长因子组>维拉帕米组>空白对照组。 结论：维拉帕米与神经生长因子对促进周围神经形态结构和功能的恢复均具有明显的协同作用。     

无细胞神经移植物复合骨髓间充质干细胞修复大鼠坐骨神经缺损

背景：作者前期试验已成功制备了天然可生物降解的无细胞神经移植物并证明其可促进周围神经再生。 目的：无细胞神经移植物复合骨髓间充质干细胞构建组织工程人工神经并观察其修复大鼠坐骨神经缺损促进运动功能恢复的效果。 设计、时间及地点：随机对照动物实验，于2008-06/2009-02在辽宁医学院附属第一医院医学组织工程实验室完成。 材料：180~200 g成年健康雄性Wistar大鼠，用于制备无细胞神经移植物，100~120 g成年健康雄性Wistar大鼠，用于制备骨髓间充质干细胞，将骨髓间充质干细胞植入并与无细胞神经支架联合培养构建组织工程人工神经。 方法：180~200 g成年健康雄性SD大鼠60只构建坐骨神经15 mm缺损模型，随机分成3组，每组20只。①实验组采用组织工程人工神经桥接大鼠坐骨神经缺损。②空白对照组采用组织工程神经支架桥接大鼠坐骨神经缺损。③自体神经对照组采用自体神经移植桥接大鼠坐骨神经缺损。 主要观察指标：术后12周通过大体观察、电生理检测、组织学和小腿三头肌湿质量等方法分析评价运动功能恢复情况。 结果：①术后12周，实验组大鼠手术侧足趾可以分开，并且可以支撑着地；实验组大鼠再生神经传导速度与自体神经对照组相比，差异无显著性意义。②术后12周，实验组组织化学染色可见腓肠肌内有呈AchE阳性的运动终板整齐地排列于腓肠肌的中上部形成终板带，经结合镀银染色后可见再生的神经束及发出的分支与运动终板相连。③实验组与自体神经对照组胫骨前肌湿质量比差异无显著性意义。 结论：无细胞神经移植物复合骨髓间充质干细胞桥接大鼠坐骨神经缺损具有促进其运动功能恢复的作用。     

坐骨神经损伤模型大鼠神经传导速度及损伤运动神经元内生长相关蛋白43表达与磁刺激干预

背景：磁刺激可促进损伤神经的修复。 目的：观察磁刺激对大鼠损伤坐骨神经神经传导速度及相应水平脊髓运动神经元内生长相关蛋白43表达的影响。 方法：将60只SD大鼠随机分为实验组(n=24)、模型组(n=24)和假手术组(n=12),用一新的长17 cm的止血钳钳夹坐骨神经至第二扣,以21.95×103 Pa维持10 s制备损伤模型。造模后24 h,实验组每天给予0.09 T的磁刺激。 结果与结论：造模后第2,4,8,12周,免疫组织化学染色显示实验组脊髓L4~5运动神经元生长相关蛋白43的表达较模型组相应时间点明显增高( P < 0. 05);造模后12周,电生理检测发现,与模型组比较,实验组再生神经传导速度加快,波幅升高,潜伏期缩短(P < 0.05)。说明磁刺激能提高损伤坐骨神经的传导速度,增加其对应脊髓节段运动神经元中生长相关蛋白43的表达,对大鼠损伤坐骨神经的修复起促进作用。     

实验性糖尿病大鼠坐骨神经病理形态学的动态变化

目的通过HE染色在光镜及电镜下观察不同时期实验性糖尿病大鼠(DM大鼠)坐骨神经内膜毛细血管及坐骨神经的形态学改变,来揭示实验性糖尿病大鼠坐骨神经病理学的动态变化。方法采用大鼠腹腔内注射链脲菌素(STZ)溶液,制备实验性糖尿病大鼠模型。将80只Wistar大鼠随机分为正常对照组(NC组),成模即刻(0w)组、成模后4w组、8w组、12w组。应用HE染色在光镜和电镜下观察大鼠下肢坐骨神经病理形态学改变。结果造模前DM组和NC组大鼠病理形态学无显著差异;HE染色显示DM组大鼠从4w开始出现神经内膜毛细血管管壁逐渐增厚,管腔不规则,内皮细胞肿胀、变形,随病程延长而逐渐加重;同时也从4w开始出现坐骨神经有髓及无髓神经纤维排列松散,且随病程进展逐渐出现髓鞘变薄、分离、空泡形成,并伴有轴索萎缩。电镜观察结果显示DM组大鼠从4w开始出现毛细血管内皮增厚,基底膜不清楚,周围有炎细胞浸润;同时有髓神经纤维髓鞘板层薄厚不一、分离或脱落,无髓神经纤维轴索内神经丝减少,线粒体肿胀,粗面内质网扩张,可见髓样小体,且随病程延长而逐渐加重。结论DM大鼠早期4w时周围神经即可出现明显的病理形态学改变,且其损伤程度随病程的延长而加重。     

肝细胞生长因子对大鼠坐骨神经损伤保护作用的实验研究

目的探讨肝细胞生长因子(HGF)对周围神经损伤的保护作用。方法以Wistar大鼠坐骨神经捻挫为动物模型,用HGF局部给药,设立对照组。于周围神经损伤后不同时期进行感觉神经传导速度(SCV)、病理形态计量学图像分析、坐骨神经功能指数(SFI)及电镜下超微结构研究。结果HGF组SCV、SFI、有髓纤维密度高于对照组(P<001)。电镜下HGF组髓鞘的厚度、轴突直径高于对照组。结论HGF能促进大鼠坐骨神经损伤后的有髓纤维再生,并促进感觉、运动神经纤维恢复,是一种有效的治疗周围神经损伤的药物。     

局部注射骨髓间充质干细胞治疗大鼠脊髓损伤：运动功能有改善吗？

背景：目前研究多为骨髓间充质干细胞的体外培养及细胞移植对颅内疾病的治疗,对植入细胞在损伤脊髓中的成活、分化、迁移、结构重建等了解有限。 目的：探讨局部骨髓间充质干细胞移植在脊髓损伤修复中的作用和骨髓间充质干细胞替代治疗的可行性。 方法：成年健康雌性SD大鼠随机分为细胞移植组和对照组,建立SD大鼠脊髓横断损伤模型,伤后即刻分别向损伤区局部移植大鼠骨髓间充质干细胞悬液或无钙镁磷酸缓冲液。在术前和术后1 d,1周,2周,3周,4周和8周进行BBB评分,观测大鼠的运动功能,并于移植后1周免疫组织化学染色法观察BrdU标记的骨髓间充质干细胞在脊髓损伤处的存活情况,移植后4周进行损伤脊髓的大体观察和组织学检测。 结果与结论：移植后第1~8周细胞移植组BBB评分均髙于对照组;术后1周免疫组织化学染色结果显示在细胞移植组大鼠脊髓远端检测到BrdU阳性细胞,术后4周脊髓损伤处发现有神经纤维。证实通过损伤后立即局部注射的方式将骨髓间充质干细胞移植进大鼠脊髓损伤区,细胞可在损伤区存活;存活的骨髓间充质干细胞可分化为神经元,在损伤局部形成神经元通路,从而促进脊髓神经纤维传导功能的恢复,并促进高位脊髓损伤后大鼠后肢运动功能恢复。     

壳聚糖导管桥接周围神经缺损的实验研究

目的　应用壳聚糖神经导引管作为神经再生室桥接大鼠坐骨神经缺损 ,观察对神经再生的作用。方法　选用体重 2 0 0± 2 0g的Wistar大鼠 30只 ,手术造成右侧坐骨神经长约 12mm的缺损 ,以壳聚糖导管桥接神经缺损 ,以左侧正常坐骨神经作为对照 ,分别于术后 4、 12、 2 4周进行大体及显微解剖观察、组织学检查、免疫组化检查、电镜观察和神经电生理测定。结果　术后大鼠右后肢感觉、运动功能有不同程度的恢复 ;光镜和电镜组织学检查发现术后 12周再生轴突已长过神经缺损间隙 ,2 4周再生完全 ,髓鞘化良好 ,神经纤维排列整齐规则 ,导管大部分被降解吸收 ;神经电生理检查在术后 2 4周记录到再生坐骨神经的复合动作电位。结论　壳聚糖神经导引管为大鼠坐骨神经再生提供一个良好的再生微环境 ,再生坐骨神经功能恢复良好     

Immediate electrical stimulation enhances regeneration and reinnervation and modulates spinal plastic changes after sciatic nerve injury and repair

We have studied whether electrical stimulation immediately after nerve injury may enhance axonal regeneration and modulate plastic changes at the spinal cord level underlying the appearance of hyperreflexia. Two groups of adult rats were subjected to sciatic nerve section followed by suture repair. One group (ES) received electrical stimulation (3 V, 0.1 ms at 20 Hz) for 1 h after injury. A second group served as control (C). Nerve conduction, H reflex, motor evoked potentials, and algesimetry tests were performed at 1, 3, 5, 7 and 9 weeks after surgery, to assess muscle reinnervation and changes in excitability of spinal cord circuitry. The electrophysiological results showed higher levels of reinnervation, and histological results a significantly higher number of regenerated myelinated fibers in the distal tibial nerve in group ES in comparison with group C. The monosynaptic H reflex was facilitated in the injured limb, to a higher degree in group C than in group ES. The amplitudes of motor evoked potentials were similar in both groups, although the MEP/M ratio was increased in group C compared to group ES, indicating mild central motor hyperexcitability. Immunohistochemical labeling of sensory afferents in the spinal cord dorsal horn showed prevention of the reduction in expression of substance P at one month postlesion in group ES. In conclusion, brief electrical stimulation applied after sciatic nerve injury promotes axonal regeneration over a long distance and reduces facilitation of spinal motor responses.     

Effects of 660‐nm gallium–aluminum–arsenide low‐energy laser on nerve regeneration after acellular nerve allograft in rats

Purpose : The purpose of this study was to explore and discuss the effects of 660‐nm gallium–aluminum–arsenide low‐energy laser (GaAlAs LEL) irradiation on neural regeneration after acellular nerve allograft repair of the sciatic nerve gap in rats. Methods : Eight male and female Sprague–Dawley rats were used as nerve donors, and 32 healthy Wistar rats were randomly divided into four groups: normal control group, acellular rat sciatic nerve (ARSN) group, laser group, and autograft group. Twelve weeks after surgery, nerve conduction velocity, restoration rate of tibialis anterior wet muscle weight, myelinated nerve number, and calcitonin gene‐related peptide (CGRP) protein and mRNA expression of the spinal cord and muscle at the injury site were quantified and statistically analyzed. Results : Compared with the ARSN group, laser therapy significantly increased nerve conduction velocity, restoration rate of tibialis anterior wet muscle weight, myelinated nerve number, and CGRP protein and mRNA expression of the L₄ spinal cord at the injury site. Conclusions : These findings demonstrate that 660‐nm GaAlAs LEL therapy upregulates CGRP protein and mRNA expression of the L₄ spinal cord at the injury site and increases the rate of regeneration and target reinnervation after acellular nerve allograft repair of the sciatic nerve gap in rats. Low‐energy laser irradiation may be a useful, noninvasive adjunct for promoting nerve regeneration in surgically induced defects repaired with ARSN. Synapse 64:152–160, 2010. © 2009 Wiley‐Liss, Inc.     

Pulsed electrical stimulation protects neurons in the dorsal root and anterior horn of the spinal cord after peripheral nerve injury

Most studies on peripheral nerve injury have focused on repair at the site of injury, but very few have examined the effects of repair strategies on the more proximal neuronal cell bodies. In this study, an approximately 10-mm-long nerve segment from the ischial tuberosity in the rat was transected and its proximal and distal ends were inverted and sutured. The spinal cord was subjected to pulsed electrical stimulation at T10 and L3, at a current of 6.5 m A and a stimulation frequency of 15 Hz, 15 minutes per session, twice a day for 56 days. After pulsed electrical stimulation, the number of neurons in the dorsal root ganglion and anterior horn was increased in rats with sciatic nerve injury. The number of myelinated nerve fibers was increased in the sciatic nerve. The ultrastructure of neurons in the dorsal root ganglion and spinal cord was noticeably improved. Conduction velocity of the sciatic nerve was also increased. These results show that pulsed electrical stimulation protects sensory neurons in the dorsal root ganglia as well as motor neurons in the anterior horn of the spinal cord after peripheral nerve injury, and that it promotes the regeneration of peripheral nerve fibers.     

Neurotrophic factors improve muscle reinnervation from embryonic neurons

Motoneurons die in diseases like amyotrophic lateral sclerosis and after spinal cord trauma, inducing muscle denervation. We tested whether transplantation of embryonic cells with neurotrophic factors into peripheral nerve of adult rats improves muscle reinnervation and motor unit function more than cells alone. One week after sciatic nerve section, embryonic ventral spinal cord cells were transplanted into the tibial nerve with or without glial cell line-derived neurotrophic factor, hepatocyte growth factor, and insulin-like growth factor-1. These cells represented the only neuron source for muscle reinnervation. Ten weeks after transplantation, all medial gastrocnemius muscles contracted in response to electrical stimulation of cell transplants with factors. Only 80% of muscles responded with cells alone. Factors and cells resulted in survival of more motoneurons and reinnervation of more muscle fibers for a given axon (motor unit) number. Greater reinnervation from embryonic cells may enhance muscle excitation by patterned electrical stimulation.     

Olfactory ensheathing cells can reduce the tissue loss but not the cavity formation in contused spinal cord of rats

In recent years, olfactory ensheathing cells (OECs) have been used as a therapeutic strategy to repair the anatomical structure and promote the function recovery of injured spinal cord in both animal and human. In this study, OECs were transplanted into contused spinal cords of adult rats. After dorsal laminectomy at T10 vertebra, spinal cord was injured by a force of 10 g with NYU II impactor from 25 mm above the exposed cord. The contused spinal cord received injections of OECs in DMEM or DMEM alone at one week after injury. The migration and distribution of OECs in the contused spinal cord were observed by the light microscope. The intact tissue area, injured tissue area, cavity size, number of myelinated nerve fibers and neurons labeled by CB-HRP in T8 segment were measured and counted by the semi-quantitative techniques at 6 weeks after transplantation. Locomotor ability and conductive function of the spinal cord were evaluated by the BBB score and cortical somatosensory evoked potentials (CSEP) recording. OECs were found in both lesion site and tissue near the lesion. The intact tissue area was significantly larger in the OECs-transplanted rats than that in the DMEM-injected animals, whereas the injured tissue area was significantly smaller in the OECs-rats than that in the DMEM-rats. The number of myelinated nerve fibers in the lesion site and preserved neurons in T8 was significantly greater in the OECs-group than in the DMEM-group, but the cavity size detected was not significantly different between the two groups. The BBB score and CSEP recording showed a better performance of locomotor ability and conductive function in the OECs-transplanted rats than in the DMEM-injected animals. These results indicate that OECs can counteract secondary tissue degeneration after spinal cord injury. Although they cannot reduce the cavity formation, they can promote morphological preservation and functional improvement of the contused spinal cord.     

A-fiber sprouting in spinal cord dorsal horn is attenuated by proximal nerve stump encapsulation

Peripheral nerve transection in the rat alters the spinal cord dorsal horn central projections from both small and large DRG neurons. Injured neurons with C-fibers exhibit transganglionic degeneration of their terminations within lamina II of the spinal cord dorsal horn, while peripheral nerve injury of medium to large neurons induces collateral sprouting of myelinated A-fibers from lamina I and III/IV into lamina II in rats, cats, and primates. To date, it is not known what sequelae are responsible for the collateral sprouting of A-fibers after peripheral nerve injury, although target-derived factors are thought to play an important role. To determine whether target-derived factors are necessary for changes in A-fiber laminar terminations in rat spinal cord dorsal horn, we unilaterally transected the sciatic nerve and ensheathed the proximal nerve stump in a silicone cap. Three days before sacrifice of rat, the injured sciatic nerve was injected with cholera toxin beta-subunit conjugated to horseradish peroxidase (betaHRP) that effectively labels both peripheral and central A-fiber axons. The effect of the ligature, axotomy, and silicone cap treatment was evaluated by analyzing the extent of betaHRP-, Substance P-(SP-), and isolectin B4- (IB4-) immunoreactive (ir) fibers in the somatotopically appropriate spinal cord dorsal horn regions. In all animals, 2-5 weeks after nerve transection (treated or otherwise), IB4- and SP-ir is absent from lamina II. Animals without nerve cap treatment exhibited robust fiber sprouting into lamina II at 2 weeks. In sharp contrast, animals treated with silicone caps did not exhibit betaHRP-ir fibers in lamina II at 2 weeks. This observation was extended up to 5 weeks postinjury. These results suggest that axotomy-induced expansion of betaHRP-ir primary afferent central terminations in the spinal cord dorsal horn is dependent on factors produced in the injury site milieu. While our understanding of local repair mechanisms of injured peripheral nerves is incomplete, it is clear that the time-dependent production of growth factors in the nerve injury microenvironment favor nerve fiber outgrowth, both peripherally and centrally.     

Midkine expression in rat spinal motor neurons following sciatic nerve injury

Midkine (MK), a heparin-binding growth factor, is produced in the developing and damaged nervous system. However, the role of MK in peripheral nerve injury has not been clarified. Here, we investigated MK expression in lumbar spinal motor neurons after rat sciatic nerve injury by immunohistochemical, in situ hybridization, and Western blot analyses. The rat sciatic nerve showed complete degeneration after local freezing. Numerous regenerated myelinated and thin nerve fibers were observed 3 weeks after injury. Intense MK immunoreactivity was detected in the ipsilateral spinal motor neurons of the anterior horn of the lumbar spinal cord after 1 day and in ipsilateral and contralateral spinal motor neurons from 4 days to 1 week after injury. It decreased after 2 weeks and again transiently increased in spinal motor neurons after 3 weeks. MK was found in the motor neurons and axon of the sciatic nerve. However, it was not detected in normal neurons and axon. In situ hybridization showed the expression of MK mRNA in lumbar spinal motor neurons of the anterior horn, but it was not present in Schwann cells or non-neuronal cells. Low-density lipoprotein receptor-related protein (LRP) immunoreactivity, a cell membrane receptor of MK, was observed in anterior horn motor neurons, but receptor-type protein tyrosine phosphatase zeta (PTPzeta) immunoreactivity as a signaling receptor complex of MK was not observed. LRP and PTPzeta immunoreactivities were observed in Schwann cells of the injured and uninjured sciatic nerve. Our findings suggest that MK is synthesized, released, and taken up in anterior horn motor neurons in an autocrine fashion with LRP. MK may have a role in degeneration and regeneration after peripheral nerve injury.     

Evaluation of regeneration of nerve and reinnervation of skeletal muscle in the hibernating ground squirrel

The retrograde transport of HRP was used to determine the status of axonal transport in the peroneal and sciatic nerves of hibernating and nonhibernating ground squirrels following crush of the peroneal nerve at 10 to 12 mm (SNS) or sciatic nerve at 33 to 35 mm (LNS) from its entrance into the extensor muscle. The ability of the proximal segment to reestablish axonal continuity and thus neuromuscular transmission was also studied. Two weeks to 3 months after nerve crush the extensor muscles were injected with HRP. We found that during hibernation no axonal transport across the site of crush was seen even after 3 months and that regeneration of the nerve during this period was minimal. Evidence of slight regeneration seen at 90 days could be due to periods of awaking of the animals during their natural hibernation cycle. In these animals HRP deposits were seen only in the nerve distal to crush, i.e., between crush site and muscle. In the nonhibernating squirrels, axoplasmic flow was reestablished at the site of injury as early as 2 weeks after crush, and HRP could be detected in the spinal cord in motoneurons of the ipsilateral ventral horn at spinal levels L₃ to L₅. In one hibernating animal the peroneal nerve was crushed at the distal site (SNS) and also the spinal cord was injured by dropping a weight. After nerve crush and the spinal cord injury the hibernating state could not be maintained and the animal stayed awake 22 days. The time course of regeneration of the nerve in that animal was similar to that seen in nonhibernating squirrels. After nerve crush in nonhibernating animals, reaction product was also found in sensory cell bodies of dorsal root ganglia as well as in terminals in the substantia gelatinosa of the spinal cord at the same levels. Thus, the axonal transport occurs in hibernating and non-hibernating squirrels in both sensory and motor nerve fibers. The extensor muscle fibers of the hibernating squirrels showed substantial membrane depolarization 90 days after crush. Action potentials from these fibers could be obtained from 15 to 35 days only through stimulating the nerve segment distal to the crush. Stimulation of the proximal nerve segment did not evoke muscle activity. These results demonstrate that nerve regeneration was nearly abolished during hibernation and that blockade of axonal transport continued across a region of nerve crush for the duration of the hibernating period.     

他克莫司促进神经干细胞移植大鼠脊髓损伤的再生与修复

背景：研究证实,他克莫司不仅抑制T细胞的增殖、活化,还能抑制小胶质细胞、巨噬细胞等炎症细胞在损伤局部聚集、活化及相关炎症因子的释放,减轻继发性炎症反应对原发损伤周围正常组织的破坏,从而对损伤局部的神经组织起保护作用。 目的：观察他克莫司对神经干细胞移植大鼠脊髓损伤后再生修复的影响。 方法：分离培养孕13d SD大鼠神经干细胞。显微镜下动脉瘤夹夹闭SD大鼠T8脊髓,建立压迫型脊髓损伤动物模型。损伤后7 d随机数字表分为3组：对照组,于损伤中心定向注射生理盐水;细胞移植组,于损伤中心定向注射神经干细胞;他克莫司组,于损伤中心定向注射神经干细胞同时给予免疫抑制剂他克莫司1 mg/(kg•d)腹腔注射连续7 d。1,2,4,8周后,通过BDA顺行示踪、苏木精-伊红与免疫组化染色及电镜检测,观察移植后脊髓组织再生和神经元的变化。 结果与结论：对照组在损伤中心端远侧无神经纤维通过。细胞移植组与他克莫司组在治疗1周后有部分神经纤维通过,8周均有部分BDA阳性标记的皮质脊髓束再生通过脊髓损伤部位,特别是他克莫司组可延续至距损伤中心1.7 cm 。苏木精-伊红染色显示,细胞移植组与他克莫司组2周时坏死灶开始缩小,泡沫细胞减少。电镜结果显示,他克莫司组1周时即出现较正常的微丝和微管结构,8周时星形细胞、许旺细胞、髓鞘典型多见,神经轴突的终末有较多的兴奋性递质和不典型的轴树连接,出现较多的结构正常的髓鞘。说明损伤大鼠移植神经干细胞后联合应用他克莫司后可减轻早期的急性炎症反应,保证神经细胞的存活,具有神经保护和神经营养作用,可加快神经功能的恢复。