丙戊酸对脊髓损伤大鼠内源性神经干细胞增殖的影响

BACKGROUND： Valproic acid has been reported to decrease apoptosis, promote neuronal differentiation of brain-derived neural stem cells, and inhibit glial differentiation of brain-derived neural stem cells.
OBJECTIVE： To investigate the effects of valproic acid on proliferation of endogenous neural stem cells in a rat model of spinal cord injury.
DESIGN, TIME AND SETTING： A randomized, controlled, neuropathological study was performed at Key Laboratory of Trauma, Buming, and Combined Injury, Research Institute of Surgery, Daping Hospital, the Third Military Medical University of Chinese PLA between November 2005 and February 2007.
MATERIALS： A total of 45 adult, Wistar rats were randomly divided into sham surgery （n = 5）, injury （n = 20）, and valproic acid （n = 20） groups. Valproic acid was provided by Sigma, USA. METHODS： Injury was induced to the T10 segment in the injury and valproic acid groups using the metal weight-dropping method. The spinal cord was exposed without contusion in the sham surgery group. Rats in the valproic acid group were intraperitoneally injected with 150 mg/kg valproic acid every 12 hours （twice in total）.
MAIN OUTCOME MEASURES： Nestin expression （5 mm from injured center） was detected using immunohistochemistry at 1,3 days, 1, 4, and 8 weeks post-injury.
RESULTS： Low expression of nestin was observed in the cytoplasm, but rarely in the white matter of the spinal cord in the sham surgery group. In the injury group, nestin expression was observed in the ependyma and pia mater one day after injury, and expression reached a peak at 1 week （P 〈 0.05）. Expression was primarily observed in the ependymal cells, which expanded towards the white and gray matter of the spinal cord. Nestin expression rapidly decreased by 4 weeks post-injury, and had almost completely disappeared by 8 weeks. At 24 hours after spinal cord injury, there was no significant difference in nestin expression between the valproic acid and injury groups. At 1 week, there was a significant increase in the number of nestin-positive cells surrounding the central canal in valproic acid group compared with the injury group （P 〈 0.05）. Expression reached a peak by 4 weeks, and it was still present at 8 weeks.
CONCLUSION： Valproic acid promoted endogenous neural stem cell proliferation following spinal cord injury in rats.     

神经干细胞移植治疗脊髓损伤

目的:探讨神经干细胞移植对脊髓损伤大鼠后肢运动功能修复的影响。方法:SD大鼠36只,制成T10脊髓全横断损伤模型。于造模成功后1周采用局部微量注射法移植。随机分三组：A损伤对照组（n=12）仅打开椎管暴露脊髓;B移植对照组（n=12）：注射10μl DMEM/F12培养液;C细胞移植组（n=12）：移植1.0?06/ml的神经干细胞悬液10μl。移植后通过不同时间点BBB行为评分、病理组织学、免疫荧光技术评价大鼠大鼠脊髓功能修复情况及移植细胞在体内的存活、迁移、分化。 结果:在体外成功建立SD大鼠海马源性神经干细胞培养体系;B、C两组大鼠随着时间延长BBB评分均不同程度提高,从移植后2W起C组大鼠评分明显高于B组,两组比较差异有统计学意义（P<0.05）;神经干细胞移植后能够在体内继续存活、迁移并且分化为NF-200、GFAP表达阳性的神经元及星形胶质细胞。 结论:神经干细胞移植治疗脊髓损伤是一种有效的方法。     

人胚神经干细胞条件化培养基促进脊髓损伤大鼠皮质脊髓束再生

目的 研究神经干细胞条件化培养基对脊髓损伤大鼠（SCI）皮质脊髓束（CST）再生的促进作用。方法 成年雌性Wistar大鼠30只随机分为两组，神经干细胞条件化培养基治疗组和培养基对照组各15只，所有大鼠于T11水平横切脊髓。治疗组15只大鼠从固定在大鼠皮下Ommaya囊内注入神经干细胞条件化培养基，每周1次，每次注入5μl，对照组从Ommaya囊内注入同等量未培养过干细胞的培养基。利用Basso-Beattie—Bresnahan（BBB）评分客观评价后肢运动功能的恢复，检测生物素葡聚糖胺（Biotin dextran amine，BDA）示踪标记CST的再生，检测损伤部位远端的突触素表达情况。结果 所有大鼠在脊髓损伤后出现下肢截瘫，神经干细胞条件化培养基治疗组的大鼠表现为后肢运动功能的逐渐恢复，BDA标记的再生的轴突穿过了损伤处到达了脊髓的远端；对照组仅表现为轻微的组织和功能变化。治疗组大鼠脊髓在脊髓损伤处远端的神经元和BDA标记的轴突位置有突触素表达，对照组没有突触素表达。结论 神经干细胞条件化培养基可以促进SCI大鼠CST的再生以及CST和神经元之间的解剖学重建；神经于细胞治疗SCI可能通过支持治疗而非替代治疗。     

神经生长因子联合神经干细胞移植治疗大鼠脊髓损伤

背景：单纯的神经干细胞移植对受损脊髓组织的修复作用并不理想,研究证实神经生长因子兼有神经元营养和促突起生长双重作用,可以有效的促进脊髓损伤后神经功能的恢复。 目的：观察神经干细胞移植联合应用神经生长因子对脊髓损伤后大鼠运动功能恢复的影响。 方法：SD大鼠42只,建立急性脊髓损伤模型后随机分成3组,伤后1周于损伤处分别注入培养液、单纯神经干细胞或神经干细胞联合神经生长因子。于伤后1,2,4,6,8周进行BBB评分和斜板实验等运动功能检测。伤后4周取材行病理切片苏木精-伊红染色及BrdU免疫组化染色,伤后8周取材行辣根过氧化物酶示踪观察及体感诱发电位观察神经电生理恢复情况。 结果与结论：伤后4周单纯神经干细胞组、神经干细胞联合神经生长因子组大鼠后肢运动功能均有较明显恢复,神经干细胞联合神经生长因子组较单纯神经干细胞组快,差异有显著性意义(P < 0.05)。培养液组亦有所恢复,但程度较轻。病理切片显示培养液组未见神经轴索通过。单纯神经干细胞组可见少量神经轴索样结构,神经干细胞联合神经生长因子组可见较多神经轴索样结构。BrdU的阳性细胞数及HRP阳性神经纤维数：神经干细胞联合神经生长因子组>单纯神经干细胞组>培养液组且各组之间差异有显著性意义(P < 0.01)。神经干细胞联合神经生长因子组大鼠体感诱发电位的潜伏期、波幅优于单纯神经干细胞组(P < 0.05),明显优于培养液组(P < 0.01)。结果提示神经干细胞移植对于后肢功能的恢复有促进作用,联合应用神经生长因子有协同效果。     

高压氧联合神经干细胞移植治疗大鼠脊髓损伤

背景：单纯神经干细胞移植已应用于对受损脊髓组织的修复。 目的：以神经干细胞移植同时应用高压氧治疗大鼠脊髓损伤,观察联合作用对脊髓损伤大鼠运动功能恢复的影响。 方法：雌性SD大鼠60只,以半切法制成胸段脊髓半横断大鼠模型。随机分成单纯损伤组、神经干细胞移植组及高压氧治疗组,每组20只。伤后第4周取材行病理切片苏木精-伊红染色及BrdU免疫组织化学染色,第8周取材行辣根过氧化物酶示踪,透射电镜观察轴突的再生情况,通过体感诱发电位观察神经电生理恢复情况。造模后1,2,4,6,8周进行BBB评分和斜板实验等运动功能检测。 结果与结论：观察伤后4周病理切片,单纯损伤组未见神经轴索通过,神经干细胞移植组可见少量神经轴索样结构,高压氧治疗组可见较多神经轴索样结构。BrdU的阳性细胞数及辣根过氧化物酶阳性神经纤维数,高压氧治疗组最多,神经干细胞移植组次之,单纯损伤组最少,且各组之间差异有显著性意义(P < 0.05)。透射电镜下神经干细胞移植组、高压氧治疗组正中横断面可见新生的无髓及有髓神经纤维。高压氧治疗组大鼠体感诱发电位的潜伏期短于神经干细胞移植组,波幅高于神经干细胞移植组(P < 0.05),明显优于单纯损伤组(P < 0.01)。伤后4周神经干细胞移植组、高压氧治疗组大鼠后肢运动功能均有较明显恢复,高压氧治疗组较神经干细胞移植组恢复快(P < 0.05);单纯损伤组亦有所恢复,但程度较轻。提示神经干细胞移植对于脊髓损伤大鼠后肢功能的恢复有促进作用,联合应用高压氧有协同效果。     

神经干细胞与脊髓损伤的治疗*★

学术背景：脊髓损伤患者损伤平面以下感觉、运动、反射及尿便功能障碍，胚胎的脊髓组织、许旺细胞以及基因修饰的功能细胞等载体移植均有助于神经系统的恢复。其中神经干细胞因与损伤区域的细胞同源，故具有独特的治疗优势。 目的：深入认识神经干细胞与脊髓损伤治疗领域的相关研究进展。 检索策略：由该论文的研究人员应用计算机检索Pubmed与Science direct数据库2000-01/2007-05的相关文献，检索词“neural stem cells，spinal cord injury”，并限定文章语言种类为English。共检索到132篇文献，对资料进行初审，纳入标准：①文章所述内容应与神经干细胞治疗脊髓损伤相关。②同一领域选择近期发表或在权威杂志上发表的文章。③近4年文献。排除标准：①重复性研究。②Meta分析。③综述文献。 文献评价：文献的来源主要是通过对神经干细胞治疗脊髓损伤方面内容进行汇总分析，所选用的23篇文献均为临床或基础实验研究。 资料综合：①脊髓损伤后，血-脊髓屏障被破坏，多种炎性因子进入损伤区域，触发细胞坏死和凋亡等级联效应。从病理生理机制角度，脊髓损伤后出现的局部微环境改变也是造成神经系统再生失败的重要原因。②神经干细胞具备自我维持和更新的能力、增殖分裂能力、自我更新能力、多向分化潜能、一定的迁移能力。在哺乳动物中枢神经系统内，神经干细胞可从胚胎、胎儿和成人脑与脊髓组织的不同部位分离出来，并能够在体外或体内扩增，分化为神经元、星形胶质细胞和少突胶质细胞。③将神经干细胞或其分化产物移植至宿主脊髓内，继而分化为相应的神经细胞是多种中枢神经系统疾病治疗的共同途径。目前仍有许多问题亟待解决，如神经干细胞定向分化的诱导信号通路及相关作用机制；体外操作对神经干细胞分化特性的影响；移植后神经干细胞的功能状态及迁移、分化调控等。 结论：利用神经干细胞进行细胞替代和转基因治疗脊髓损伤具有较好的临床应用前景。     

神经干细胞修复脊髓损伤

背景：神经生物学和干细胞技术的发展．使通过细胞移植增加脊髓神经数量、减少胶质瘢痕和空洞的形成成为可能。 目的：复习相关文献,就神经干细胞的鉴定及特性、神经干细胞修复脊髓损伤的可能机制、临床前研究及临床应用方面进行综述。 方法：以 “neural stem cells,transplant,spinal cord injury”为英文检索词,以“神经干细胞,移植,脊髓损伤” 为中文检索词,由第一作者检索1997/2010 PubMed数据库及万方数据库有关神经干细胞鉴定、特性、神经干细胞修复脊髓损伤的可能机制、临床前研究及临床应用方面等方面的文章。排除发表时间较早、重复及类似研究,对29篇符合标准的文献进行归纳总结。 结果与结论：神经干细胞有产生神经元、少突胶质细胞、星形胶质细胞,并替代受损的神经细胞功能等。文章从神经干细胞的鉴定及特性,神经干细胞修复脊髓损伤的可能机制,神经干细胞治疗脊髓损伤的实验研究及临床应用等方面进行了讨论。关于干细胞来源的神经元或胶质细胞移植后的长期生存及表型稳定性,以及逃脱分化及选择性程序的很少部分胚胎干细胞,可能会自在移植后的移植位点扩增并形成肿瘤等问题有待进一步解决。     

神经干细胞移植治疗脊髓损伤的研究现状

脊髓完全横断性损伤引起的永久性神经功能障碍的治疗,目前还没有很有效的方法。文章介绍了对神经干细胞培养、神经干细胞表型控制及神经干细胞移植等方法的分析,介绍了神经干细胞移植治疗脊髓损伤的研究现状。目前神经干细胞移植的动物实验主要致力于提高轴突再生能力、替代细胞成分、阻止脱髓鞘和使髓鞘再生等方面,具有促进感觉及运动功能恢复的客观结果,有些甚至已经进入了临床实验阶段。不过神经干细胞的成功应用还受到很多因素的影响,诸如移植剂量、细胞生长因子的活力,细胞移植的风险等,尤其是其效果还需要进一步研究、评价,并且需要长时间的随访。关键词：神经干细胞;脊髓损伤;细胞移植     

不同来源成体神经干细胞促进大鼠脊髓损伤功能修复的比较研究

目的 评价大脑、骨髓和脂肪组织3种不同来源的神经干细胞对大鼠脊髓挫伤的治疗效果.方法 选取来源于同一大鼠成体中大脑、骨髓和脂肪的3个部位的组织,分离、诱导分化为不同来源的神经干细胞;应用自由落体损伤模型装置造成大鼠脊髓挫伤.将不同来源的神经干细胞分别移植入大鼠脊髓损伤部位,通过BBB评分比较修复脊髓损伤功能的效果,应用免疫荧光染色检测不同移植细胞在损伤脊髓中的存活、分布、迁移的情况.另设假手术对照组和生理盐水对照组.结果 与假手术对照组和生理盐水对照组比较,3个细胞处理组BBB评分在2～8周开始增加,9周以后更加明显,差异开始有统计学意义(P<0.05).在移植后1周和4周,细胞移植组中脑源性神经干细胞(SVZ-NSs)组Brdu/nestin+>神经元存活的数目明显高于其他2组.但差异没有统计学意义(P>0.05);到了第8周,3组均仅有少量Brdu/nestin+>细胞存活,相互之间比较差异无统计学意义(P>0.05).结论 植入来源于大脑、骨髓和脂肪组织的神经干细胞都可以在一定程度上提高脊髓损伤后运动功能恢复,但SVZ-NSs组的脊髓损伤大鼠运动功能恢复要比脂肪来源的神经干细胞(AD-NSs)组及骨髓来源的神经干细胞(BM-NSs)组更好.AD-NSs由于来源广泛和强有力的增殖能力,相比其他来源的神经干细胞,可能是更好的选择.     

甲基强的松龙和神经干细胞移植联合治疗大鼠脊髓损伤

目的：观察甲基强的松龙和神经干细胞移植对大鼠脊髓损伤后神经结构修复和功能恢复的治疗作用并探讨其作用机制。方法：制备大鼠胸10脊髓损伤模型，体外培养、诱导分化大鼠神经干细胞，定量评价甲基强的松龙和神经干细胞移植对脊髓损伤后神经结构修复和功能恢复的影响。结果：与对照组相比，移植组明显地增强了生长相关蛋白（GAP－43）mRNA的表达，促进了乙酰胆碱转移酶（ChAT)阳性脊髓运动神经元的再生、神经结构的修复和下肢运动功能的恢复（P＜0．05）。结论：甲基强的松龙和神经干细胞移植通过增强GAP－43 mRNA的表达、运动神经元的再生而促进了脊髓损伤后神经结构的修复和功能的恢复，是急性脊髓损伤的一种有效的治疗方案。     

Differentiation of endogenous neural precursors following spinal cord injury in adult rats

BACKGROUND:Studies have shown that cell death can activate proliferation of endogenous neural stem cells and promote newly generated cells to migrate to a lesion site.OBJECTIVE:To observe regeneration and differentiation of neural cells following spinal cord injury in adult rats and to quantitatively analyze the newly differentiated cells.DESIGN,TIME AND SETTING:A cell biology experiment was performed at the Institute of Orthopedics and Medical Experimental Center,Lanzhou University.between August 2005 and October 2007.MATERIALS:Fifty adult,Wistar rats of both sexes;5-bromodeoxyuridine(BrdU,Sigma,USA);antibodies against neuron-specific enolase,glial fibrillary acidic protein,and myelin basic protein(Chemicon,USA).METHODS:Twenty-five rats were assigned to the spinal cord injury group and received a spinal cord contusion injury.Materials were obtained at day 1,3,7,15,and 29 after injury,with 5 rats for each time point.Twenty-five rats were sham-treated by removing the lamina of the vertebral arch without performing a contusion.MAIN OUTCOME MEASURES:The phenotype of BrdU-labeled cells,i.e.,expression and distribution of surface markers for neurons(neuron-specific enolase),astrocytes(glial fibrillary acidic protein),and oligodendrocytes(myelin basic protein),were identified with immunofluorescence double-labeling.Confocal microscopy was used to detect double-labeled cells by immunofluorescence.Quantitative analysis of newly generated cells was performed with stereological counting methods.RESULTS:There was significant cell production and differentiation after adult rat spinal cord injury.The quantity of newly-generated BrdU-labeled cells in the spinal cord lesion was 75-fold greater than in the corresponding area of control animals.Endogenous neural precursor cells differentiated into astrocytes and oligodendrocytes,however spontaneous neuronal difierentiation was not detected.Between 7 and 29 d after spinal cord injury,newly generated cells expressed increasingly more mature oligodendrocyte and astrocyte markers.CONCLUSION:Spinal cord injury is a direct inducer of regeneration and differentiation of neural cells.Endogenous neural precursor cells Can difierentiate into astrocytes and oligodendrocytes following adult rat spinal cord injury.     

Hypoxia-specific VEGF-expressing neural stem cells in spinal cord injury model

We established three stable neural stem cell (NSC) lines to explore the possibility of using hypoxia-specific vascular endothelial growth factor (VEGF) expressing NSC lines (EpoSV-VEGF NSCs) to treat spinal cord injury. The application of EpoSV-VEGF NSCs into the injured spinal cord after clip compression injury not only showed therapeutic effects such as extended survival and angiogenesis, but also displayed its safety profile as it did not cause unwanted cell proliferation or angiogenesis in normal spinal cord tissue, as EpoSV-VEGF NSCs consistently showed hypoxia-specific VEGF expression patterns. This suggests that our EpoSV-VEGF NSCs are both safe and therapeutically efficacious for the treatment of spinal cord injury. Furthermore, this hypoxia-inducible gene expression system may represent a safe tool suitable for gene therapy.     

Differentiation of endogenous neural precursors following spinal cord injury in adult rats☆

BACKGROUND： Studies have shown that cell death can activate proliferation of endogenous neural stem cells and promote newly generated cells to migrate to a lesion site.
OBJECTIVE： To observe regeneration and differentiation of neural cells following spinal cord injury in adult rats and to quantitatively analyze the newly differentiated cells.
DESIGN, TIME AND SETTING： A cell biology experiment was performed at the Institute of Orthopedics and Medical Experimental Center, Lanzhou University, between August 2005 and October 2007.
MATERIALS： Fifty adult, Wistar rats of both sexes; 5-bromodeoxyuridine （BrdU, Sigma, USA）; antibodies against neuron-specific enolase, glial fibrillary acidic protein, and myelin basic protein （Chemicon, USA）.
METHODS： Twenty-five rats were assigned to the spinal cord injury group and received a spinal cord contusion injury. Materials were obtained at day 1, 3, 7, 15, and 29 after injury, with 5 rats for each time point. Twenty-five rats were sham-treated by removing the lamina of the vertebral arch without performing a contusion.
MAIN OUTCOME MEASURES： The phenotype of BrdU-labeled cells, i.e., expression and distribution of surface markers for neurons （neuron-specific enolase）, astrocytes （glial fibrillary acidic protein）, and oligodendrocytes （myelin basic protein）, were identified with immunofluorescence double-labeling. Confocal microscopy was used to detect double-labeled cells by immunofluorescence. Quantitative analysis of newly generated cells was performed with stereological counting methods.
RESULTS： There was significant cell production and differentiation after adult rat spinal cord injury. The quantity of newly-generated BrdU-labeled cells in the spinal cord lesion was 75-fold greater than in the corresponding area of control animals. Endogenous neural precursor cells differentiated into astrocytes and oligodendrocytes, however spontaneous neuronal differentiation was not detected. Between 7 and 29 d after spinal cord injury, newl     

Transplantation of neural stem cells for spinal cord injury]

Neural progenitor cells, including neural stem cells (NSCs), are an important potential graft material for cell therapeutics of damaged spinal cord. Here we used as a source of graft material a NSC-enriched population derived from human fetal spinal cord (Embryonic week 8-9) and expanded in vitro by neurosphere formation. NSCs labeled with BrdU (TP) or culture medium (CON) were transplanted into the adult marmoset spinal cord after contusion injury at C5 level. Grafted NSCs survived and migrated up to 7 mm far from the lesion epicenter. Double-staining with TuJ1 for neuron, GFAP for astrocyte, or CNPase for oligodendrocyte and BrdU revealed that grafted NSCs differentiated into neurons and oligodendrocytes 8 weeks after transplantation. More neurofilaments were observed in TP than those of CON. Furthermore, behavioral assessment of forelimb muscle strength using bar grip test and amount of spontaneous motor activity using infrared-rays monitoring revealed that the grafted NSCs significantly increased both of them compared to those of CON. These results indicate that in vitro expanded NSCs derived from human fetal spinal cord are useful sources for the therapeutics of spinal cord injury in primates.     

Fate of endogenous stem/progenitor cells following spinal cord injury

The adult mammalian spinal cord contains neural stem and/or progenitor cells that slowly multiply throughout life and differentiate exclusively into glia. The contribution of adult progenitors to repair has been highlighted in recent studies, demonstrating extensive cell proliferation and gliogenesis following central nervous system (CNS) trauma. The present experiments aimed to determine the relative roles of endogenously dividing progenitor cells versus quiescent progenitor cells in posttraumatic gliogenesis. Using the mitotic indicator bromodeoxyuridine (BrdU) and a retroviral vector, we found that, in the adult female Fisher 344 rat, endogenously dividing neural progenitors are acutely vulnerable in response to T8 dorsal hemisection spinal cord injury. We then studied the population of cells that divide postinjury in the injury epicenter by delivering BrdU or retrovirus at 24 hours after spinal cord injury. Animals were euthanized at five timepoints postinjury, ranging from 6 hours to 9 weeks after BrdU delivery. At all timepoints, we observed extensive proliferation of ependymal and periependymal cells that immunohistochemically resembled stem/progenitor cells. BrdU+ incorporation was noted to be prominent in NG2-immunoreactive progenitors that matured into oligodendrocytes, and in a transient population of microglia. Using a green fluorescence protein (GFP) hematopoietic chimeric mouse, we determined that 90% of the dividing cells in this early proliferation event originate from the spinal cord, whereas only 10% originate from the bone marrow. Our results suggest that dividing, NG2-expressing progenitor cells are vulnerable to injury, but a separate, immature population of neural stem and/or progenitor cells is activated by injury and rapidly divides to replace this vulnerable population.     

Repair of spinal cord injury by neural stem cells modified with BDNF gene in rats

Objective To explore repair of spinal cord injury by neural stem cells (NSCs) modified with brain derived neurotrophic factor (BDNF) gene (BDNF-NSCs) in rats. Methods Neural stem cells modified with BDNF gene were transplanted into the complete transection site of spinal cord at the lumbar 4 (L4) level in rats. Motor function of rats' hind limbs was observed and HE and X-gal immunocytochemical staining, in situ hybridization, and retrograde HRP tracing were also performed, Results BDNF-NSCs survived and integrated well with host spinal cord. In the transplant group, some X-gal positive, NF-200 positive, GFAP positive, BDNF positive, and BDNF mRNA positive cells, and many NF-200 positive nerve fibers were observed in the injury site. Retrograde HRP tracing through sciatic nerve showed some HRP positive cells and nerve fibers near the rostral side of the injury one month after transplant and with time, they increased in number. Examinations on rats' motor function and behavior demonstrated that motor function of rats' hind limbs improved better in the transplant group than the injury group. Conclusion BDNF-NSCs can survive, differentiate, and partially integrate with host spinal cord, and they significantly ameliorate rats' motor function of hind limbs, indicating their promising role in repairing spinal cord injury.     

Repair of spinal cord injury by neural stem cells modified with BDNF gene in rats

Objective To explore repair of spinal cord injury by neural stem cells （NSCs） modified with brain derived neurotrophic factor （BDNF） gene （BDNF-NSCs） in rats. Methods Neural stem cells modified with BDNF gene were transplanted into the complete transection site of spinal cord at the lumbar 4 （L4） level in rats. Motor function of rats＇ hind limbs was observed and HE and X-gal immunoeytochemical staining, in situ hybridization, and retrograde HRP tracing were also performed. Results BDNF-NSCs survived and integrated well with host spinal cord. In the transplant group, some X-gal positive, NF-200 positive, GFAP positive, BDNF positive, and BDNF mRNA positive cells, and many NF-200 positive nerve fibers were observed in the injury site. Retrograde HRP tracing through sciatic nerve showed some HRP positive cells and nerve fibers near the rostral side of the injury one month after transplant and with time, they increased in number. Examinations on rats＇ motor function and behavior demonstrated that motor function of rats＇ hind limbs improved better in the transplant group than the injury group. Conclusion BDNF-NSCs can survive, differentiate, and partially integrate with host spinal cord, and they significantly ameliorate rats＇ motor function of hind limbs, indicating their promising role in repairing spinal cord injury.     

Effects of microtubule-associated protein tau expression on neural stem cell migration after spinal cord injury

Our preliminary proteomics analysis suggested that expression of microtubule-associated protein tau is elevated in the spinal cord after injury. Therefore, the first aim of the present study was to examine tau expression in the injured spinal cord. The second aim was to determine whether tau can regulate neural stem cell migration, a critical factor in the successful treatment of spinal cord injury. We established rat models of spinal cord injury and injected them with mouse hippocampal neural stem cells through the tail vein. We used immunohistochemistry to show that the expression of tau protein and the number of migrated neural stem cells were markedly increased in the injured spinal cord. Furthermore, using a Transwell assay, we showed that neural stem cell migration was not affected by an elevated tau concentration in the outer chamber, but it was decreased by changes in intracellular tau phosphorylation state. These results demonstrate that neural stem cells have targeted migration capability at the site of injury, and that although tau is not a chemokine for targeted migration of neural stem cells, intracellular tau phosphorylation/dephosphorylation can inhibit cell migration.     

针刺督脉经穴和夹脊穴对脊髓损伤大鼠神经干细胞的作用

目的 探讨针刺督脉经穴和夹脊穴对脊髓损伤大鼠神经功能恢复和内源性神经干细胞增殖的影响.方法 48只6周龄SD大鼠以改良Allen wD法制作成脊髓损伤模型,并按随机数字表法分为A组和B组,每组义分为14d、30d、60d和90d4个时间点.A组每天针刺督脉经穴和夹脊穴1次,B组不针刺.各组在相应时间点取材前连续3 d腹腔注射BrdU标记增殖的内源性神经干细胞.各组分别在术后1 d、14 d、30 d、60 d和90d用Tarlov评分和IP评分评价双后肢功能,术后14 d、30 d、60 d和90 d评分后取材进行抗BrdU免疫组化染色.观察各切片BrdU阳性细胞数目及分布情况.结果 双后肢功能评分显示术后14 d、30 d、60 d和90 d A组双下肢功能改善与B组比较差异有统汁学意义(P<0.05),功能改善与治疗时间延长平行.免疫组化染色显示术后14 d、30 d、60 d和90 d A组BrdU阳性细胞数和B组比较差异有统计学意义(P<0.05).结论 针刺督脉经穴和夹脊穴能促进脊髓损伤大鼠双下肢功能恢复和原位诱导脊髓内源性神经干细胞增殖.     

Human umbilical cord blood stem cells upregulate matrix metalloproteinase-2 in rats after spinal cord injury

Matrix metalloproteinases (MMPs) are a large family of proteolytic enzymes involved in inflammation, wound healing and other pathological processes after neurological disorders. MMP-2 promotes functional recovery after spinal cord injury (SCI) by regulating the formation of a glial scar. In the present study, we aimed to investigate the expression and/or activity of several MMPs, after SCI and human umbilical cord blood mesenchymal stem cell (hUCB) treatment in rats with a special emphasis on MMP-2. Treatment with hUCB after SCI altered the expression of several MMPs in rats. MMP-2 is upregulated after hUCB treatment in spinal cord injured rats and in spinal neurons injured either with staurosporine or hydrogen peroxide. Further, hUCB induced upregulation of MMP-2 reduced formation of the glial scar at the site of injury along with reduced immunoreactivity to chondroitin sulfate proteoglycans. Blockade of MMP-2 activity in hUCB cocultured injured spinal neurons reduced the protection offered by hUCB which indicated the involvement of MMP-2 in the neuroprotection offered by hUCB. Based on these results, we conclude that hUCB treatment after SCI upregulates MMP-2 levels and reduces the formation of the glial scar thereby creating an environment suitable for endogenous repair mechanisms.