bFGF通过抑制Nogo-A信号减少脊髓损伤后胶质瘢痕形成

脊髓损伤后胶质瘢痕的形成是阻碍神经恢复的关键原因之一。碱性成纤维细胞生长因子（basic fibroblast growth factor,bFGF）具有良好的神经保护及促进脊髓损伤的修复作用,然而其对于胶质瘢痕的影响及其机制仍不清楚。本研究通过采用血管动脉夹（30 g）夹闭雌性SD大鼠脊髓2 min造成急性脊髓损伤模型并予以每天皮下注射bFGF（80 μg/kg）,探讨bFGF促进脊髓损伤的恢复作用是否涉及到胶质瘢痕调控和Nogo-A/NgR信号的相关机制。通过检测损伤后28 d,各组BBB评分和斜板试验,发现bFGF显著促进脊髓损伤后大鼠运动功能的恢复。HE及尼氏染色显示,bFGF处理组相对于生理盐水处理组,其神经元明显增多,空洞面积减少。同时,星形胶质细胞标记物GFAP免疫荧光结果表明,bFGF减少胶质瘢痕形成,抑制星形胶质细胞过度激活。同样,通过Western 印迹检测发现,bFGF处理后,胶质瘢痕相关蛋白（如GFAP, neurocan）以及神经突生长抑制蛋白（Nogo-A）信号通路相关蛋白质表达量下降。上述结果表明,bFGF可能通过抑制Nogo-A信号蛋白的表达,从而抑制胶质瘢痕的形成,促进脊髓损伤的恢复。此机制研究为脊髓损伤的治疗和恢复提供全新的思路和药物靶点。     

干细胞治疗脊髓损伤研究进展

脊髓损伤后的常规治疗手段是在有效时间内进行手术缓减外力压迫,防止脊髓神经进一步受损。细胞替代治疗理论上可治愈脊髓损伤,不同类型细胞可从各角度产生治疗作用,包括损伤后的脊髓轴突再生、神经元再建和轴突髓鞘化等,进而促进功能恢复。对近年来干细胞治疗脊髓损伤研究中的最新结果进行了概述,以期为干细胞治疗脊髓损伤的研究提供参考。     

间充质干细胞-透明质酸-多聚赖氨酸治疗脊髓损伤的实验研究

目的研究间充质干细胞—透明质酸—多聚赖氨酸复合物治疗脊髓损伤的可行性,评价其治疗效果并探讨其可能机制。方法从人骨髓中分离、培养人骨髓间充质干细胞（human bone marrow mesenchymal stem cell,hBMSC）;制作大鼠脊髓半横断模型,按照实验分组分别将hBMSC、透明质酸-多聚赖氨酸（hyaluronic acid-poly-L-lysine,HA-PLL）、hBMSC-HA-PLL复合物注入损伤区域,单纯损伤组作为对照。术后按照不同时间点评价损伤和移植后的大鼠运动功能。8周后杀死大鼠,观察不同移植组体内轴突和血管生长的情况,对不同细胞、材料及复合物移植对大鼠脊髓损伤修复效果进行评估。结果 hBMSC移植组和hBMSC-HA-PLL移植组的大鼠运动功能的改善显著好于单纯损伤及HA-PLL移植组。电镜结果证实复合物移植组可显著促进轴突和血管生长,新生的轴突和血管结构较为完整。结论 hBMSC具有促进神经功能恢复的作用,将其与HA-PLL相结合,可以促进大鼠脊髓损伤修复,其机制可能包括材料框架作用和hBMSC在体内对大鼠神经细胞的营养作用以及促进微血管的生成。     

MSCs线粒体转移对脑缺血后损伤修复的作用研究

目的探索骨髓基质细胞（MSCs）中线粒体转移在脑缺血后的损伤保护作用。 方?法采用小鼠骨髓MSCs分离与原代培养方法,培养MSCs并通过流式细胞仪进行鉴定;取出生后第0天（P0）SD幼鼠的皮层,进行原代神经元培养,并进行氧糖剥夺（OGD）处理,将含有线粒体的MSCs培养基（MCM）组和不含有线粒体的MSCs培养基（mdMCM）组与OGD神经元进行共培养,另以未经过OGD处理的神经元（Neuron组）和经过OGD处理的神经元（OGD组）作为对照;通过MitoTracker追踪线粒体,分析线粒体从MSCs向OGD神经元的转移情况;通过检测试剂盒对神经元内ATP含量和神经元活性进行分析;通过对线粒体膜电势检测,分析线粒体的功能;采用Western Blot分析线粒体Miro1蛋白的表达水平;通过MCAO造模和计算梗死体积,分析MSCs移植对脑缺血的保护作用。采用方差分析和t检验进行统计学分析。 结?果原代培养的骨髓MSCs纯度达到99﹪以上。取原代培养MSCs的培养基分别去除线粒体（mdMCM）与不去除线粒体（MCM）,与OGD神经元共培养,在MCM组,观察到神经元中存在MSCs来源的线粒体;经过OGD处理的神经元,其胞内ATP水平降低至0.634±0.023,给予MCM处理后,神经元胞内ATP水平上升至1.623±0.039,当给予mdMCM处理后,神经元胞内ATP水平降低至0.645±0.011,ATP比率变化的差异具有统计学意义（F?= 3413.62,P?< 0.01）;经过OGD处理,神经元活性降低至（73.7±1.12）﹪;给予MCM处理后,神经元活升高到（83.3±1.57）﹪,当给予mdMCM处理后,神经元活性降低至（72.9±1.25）﹪,与MCM组相比差异具有统计学意义（F?= 654.280,P?< 0.01）。在未经过处理的对照组中,线粒体膜电势丢失1.7﹪;经过OGD处理后,膜电势丢失70.3﹪;添加MCM后的OGD神经元,线粒体膜电势丢失44.7﹪,与OGD组相比,差异具有统计学意义（P?= 0.036）;而添加mdMCM的OGD处理神经元,线粒体膜电势丢失67.7﹪,与OGD+MCM组相比,差异具有统计学意义（P?= 0.041）。给予CCCP处理后的阳性对照神经元,膜电势丢失为99.3﹪。在Miro1表达干预中,空白对照组神经元胞内的ATP平均水平记为1,神经元活性为100﹪,计算其余各组相对空白对照组的ATP水平和神经元活性。在Miro1高表达组,胞内ATP水平为2.304,与对照质粒组（ratio = 1.611）相比,差异具有统计学意义（P?= 0.034）;神经元活性检测中,Miro1高表达组相比对照质粒组（90.4﹪vs 81.7﹪）,差异具有统计学意义（P?= 0.040）。在MCAO手术后,小鼠的脑梗死体积达到38.4﹪,而给予MSCs后的小鼠,梗死面积降低到14.4﹪,差异具有统计学意义（P?= 0.004）。 结论MSCs来源的线粒体可以向损伤神经元转移,提升神经元胞内ATP水平和神经元活性,降低缺血损伤中小鼠的脑梗死体积。线粒体Miro1蛋白参与了线粒体向神经元转移保护过程。     

脊髓损伤再生轴突生长的数学模型和三维格子波尔兹曼法数值模拟

中枢神经系统损伤是当今社会最具破坏力的疾病之一,虽然已经有办法使损伤后残存的神经元出芽,但如何保证处于萌芽状态的再生轴突继续生长直至与远端的靶细胞正确连接,是困扰至今的难题。为探讨中枢神经损伤所形成的胶质瘢痕和其所诱导的抑制因子对再生轴突生长进程的影响,根据轴突生长速度与其微环境中影响因子的浓度梯度成比例的原理,以脊髓损伤为背景构建数学模型,并采用格子波尔兹曼法进行三维数值模拟。数值试验中的主要观察指标为:1)当微环境中轴突生长抑制因子释放率和促进因子释放率一定时,胶质瘢痕的轴向厚度对轴突生长速率的影响,并跟踪记录生长锥所经过路线上的抑制因子浓度和促进因子浓度;2)当胶质瘢痕的轴向厚度一定时,抑制因子释放率和促进因子释放率对轴突生长速率的影响,并跟踪记录生长锥所经过路线上的抑制因子浓度和促进因子浓度。结果表明:1)胶质瘢痕的轴向厚度越大、抑制因子的释放率越强,轴突生长速率越小;2)轴突生长速率本质上取决于生长锥所在位置抑制因子浓度与促进因子浓度的比值,当该比值平均小于某个阈值时,再生轴突能够顺利生长并与靶细胞成功对接。为正确设计有关动物试验提供了理论参考。     

纤维蛋白原通过激活EGFR信号通路抑制体外低糖低氧损伤神经元轴突再生

目的 探讨纤维蛋白原（fibrinogen,Fg）对体外低糖低氧（low glucose and oxygen,LGO）损伤神经元轴突再生的影响及机制。方法 取出生后24 h内乳鼠皮层神经元进行原代培养,通过免疫荧光染色检测MAP-2鉴定神经元。将细胞分为3组,即LGO组、LGO+Fg组、LGO+Fg+PD168393组。3组均予以低糖低氧处理48 h后, LGO+Fg组加入Fg,LGO+Fg+PD168393组加入Fg、表皮生长因子受体（epidermal growth factor receptor,EGFR）抑制剂（PD168393）,均处理细胞24 h。采用免疫荧光染色检测β-tubulin III(Tuj-1)表达,评价轴突生长;Western blot检测EGFR、p-EGFR在细胞中的表达;实时荧光定量PCR检测EGFR下游调控蛋白（MAP-1B,CRMP-2）mRNA表达。结果 与LGO组比较,LGO+Fg组轴突生长明显受到抑制,轴突长度较短、数量减少,p-EGFR蛋白表达显著增加,MAP-1B、CRMP-2 mRNA表达下调;与LGO+Fg组比较,LGO+Fg+PD1...     

精氨酸酶Ⅰ参与环腺苷酸促进脑缺血再灌注大鼠的轴突再生

环腺苷酸（cAMP）作为细胞内的重要第二信使之一,主要通过激活下游cAMP依赖性蛋白激酶A（PKA）,进一步激活转录因子-cAMP效应元件结合蛋（CREB）,达到促进损伤轴突再生的作用.精氨酸酶Ⅰ主要是通过促进多胺的表达,从而克服髓鞘相关抑制因子对轴突再生的抑制作用,达到促进轴突再生的效果.在脑缺血中,cAMP促进轴突再生的过程是否有精氨酸酶Ⅰ的参与及其与RhoA信号通路的关系尚不清楚.本研究采用线栓法制备脑缺血再灌注模型（MACO）,采用Longa 5评分法对大鼠运动功能进行评分,利用逆转录聚合酶链反应（RT-PCR）和Western蛋白印迹方法分别检测缺血灶周边脑组织生长相关蛋白43（GAP-43）和RhoA的mRNA和蛋白表达,免疫组化法进行GAP-43的形态学检测,作为轴突再生的标志.通过尾静脉注射cAMP类似物db-cAMP增加脑缺血后大鼠脑组织内cAMP的浓度后发现：db-cAMP处理可明显降低MACO大鼠的运动功能评分,且可促进GAP-43 mRNA及蛋白的表达,抑制RhoA mRNA及蛋白的表达,由此可见db-cAMP处理可促进脑缺血后大鼠运动功能的恢复,且这一过程与抑制RhoA通路,进而促进轴突再生有关;通过在db-cAMP的基础上给予精氨酸酶Ⅰ拮抗剂NOHA来降低精氨酸酶Ⅰ的活性发现：给予NOHA的大鼠运动功能评分明显增加,这一变化趋势与RhoA mRNA及蛋白表达的变化趋势相一致,而与GAP-43 mRNA及蛋白表达的变化趋势相反. 因此可推断：精氨酸酶Ⅰ参与了db-cAMP促进轴突再生、改善脑缺血后大鼠运动功能的过程,且与钝化RhoA通路有关.     

miRNAs在脊髓损伤中作用的研究进展

脊髓损伤是一个重要的公共卫生难题,脊髓损伤可划分为三个病理生理阶段:原发性损伤期、继发性损伤期和慢性损伤期。基因表达的改变在脊髓损伤中起到了重要作用,miRNAs可以调控转录后所有基因的表达,所以miRNAs是脊髓损伤中一个很具有研究价值的研究对象。miRNAs是20-25碱基组成的非编码RNA,通过与靶mRNAs 3‘UTR结合下调其表达实现的对mRNA翻译进程的调控。miRNAs与中枢神经系统的发育、功能和疾病有密切关系。脊髓损伤后miRNAs通过调节中性粒细胞和炎性反应通路在炎性应答中起到了重要作用;miRNAs在细胞凋亡中表现出了复杂的功能,其表达的改变可能同时刺激和抑制凋亡;miRNAs可通过增强星形胶质细胞肥大和调节胶质瘢痕的进程;miRNAs的下调可能通过促进轴突靶向作用、神经元存活和轴突生长来促进损伤脊髓部位再生进程。目前脊髓损伤仍是现代医学的难题,对神经系统疾病中miRNAs作用的研究,为脊髓损伤治疗提供了一种新的治疗方案,也是将来研究中的热点。     

硫酸酯酶2型基因体内表达促进化疗药物诱发的小鼠骨髓抑制恢复作用研究

采用半定量RT-PCR和重组基因体内表达法观察了硫酸酯酶2基因（Sulfatase 2,Sulf2）在5-氟脲嘧啶（5-Fluorouracil, 5-Fu）诱发的小鼠骨髓抑制和再生过程中作用。结果表明：Sulf2在小鼠骨髓抑制和再生过程中呈现先上升,后下降的动态表达;电转pcDNA3.1-Sulf2基因实验组外周血白细胞数和血小板数在5-Fu注射后第7天分别为(1216.7±457.9)/μl和(8.1±5.4)万/μl,明显低于对照组［分别为(1691.7±228.9)/μl和(14.7±2.1)万/μl］,实验组单条腿骨髓细胞总数在第7天为(94.2±21.1)万,显著低于对照组（173±59.9）万,但在第11天为(585±337.9)万,又显著地高于对照组（255±65.3）万,实验组第7天10000个骨髓细胞总集落形成数为(9±8.4),显著低于对照组（39±12.2),统计均有显著性差异（p<0.05）。这些结果提示Sulf2可能对5 Fu诱发的小鼠骨髓抑制后的再生具有促进作用。     

核桃低聚肽对亚急性肾衰老大鼠肾损伤的改善作用

目的：探讨核桃低聚肽（WOPs）对D-半乳糖诱导的亚急性肾衰老大鼠肾损伤的改善作用。方法：将108只雄性SD大鼠随机分为生理盐水组、模型对照组、3个WOPs剂量组（220、440、880 mg/kg）和乳清蛋白组（440 mg/kg）,每组18只。各组每日分别腹腔注射D-半乳糖生理盐水溶液300 mg/kg,生理盐水组注射等量灭菌生理盐水,连续6 w,造成亚急性肾衰老模型。造模成功后继续进行腹腔注射并灌胃给予干预物,8 w后记录体重、计算肾脏系数,检测肾组织SOD、GSH-Px活性、GSH、MDA含量,检测血清肌酐、胱抑素C水平,检测尿微量白蛋白、尿肌酐并计算尿微量白蛋白/肌酐比值（UACR）。结果：与生理盐水组相比,模型对照组肾脏系数［（4.91±0.36）mg/g］、GSH-Px活性［（24.41±2.10）U/mg prot］显著下降,血清肌酐［（41.50±7.27）μmol/L］、UACR［（1.37±0.24）mg/g］、 MDA水平［（3.09±0.35）nmol/L］显著提高（P＜0.05）。与模型对照组相比,WOPs低剂量组血清胱抑素C水平［（0.31±0.04）mg/L］显著下降（P＜0.05）,WOPs中剂量组大鼠UACR［（0.99±0.34）mg/g］显著下降（P＜0.05）,WOPs高剂量组体重［（616.0±44.2）g］、肾脏脏器系数［（5.25±0.39）mg/g］显著提高,肌酐水平［（34.50±6.58）μmol/L］显著下降（P＜0.05）;WOPs中、高剂量组大鼠肾组织SOD活性［（71.18±7.71）、（71.95±9.56）U/mg prot］及GSH水平［（4.51±0.28）、（4.37±0.23）μmol/g prot］显著提高（P＜0.05）;WOPs低、中、高剂量组大鼠肾组织GSH-Px活性［（26.49±2.08）、（26.56±2.17）、（26.29±1.87）U/mg prot］均显著提高,MDA水平［（2.88±0.36）、（2.51±0.21）、（2.36±0.26）nmol/L］显著下降（P＜0.05）。结论：WOPs对D-半乳糖诱导的肾脏损害具有改善作用。     

Thermosensitive heparin‐poloxamer hydrogel encapsulated bFGF and NGF to treat spinal cord injury

The application of growth factors (GFs) for treating chronic spinal cord injury (SCI) has been shown to promote axonal regeneration and functional recovery. However, direct administration of GFs is limited by their rapid degradation and dilution at the injured sites. Moreover, SCI recovery is a multifactorial process that requires multiple GFs to participate in tissue regeneration. Based on these facts, controlled delivery of multiple growth factors (GFs) to lesion areas is becoming an attractive strategy for repairing SCI. Presently, we developed a GFs‐based delivery system (called GFs‐HP) that consisted of basic fibroblast growth factor (bFGF), nerve growth factor (NGF) and heparin‐poloxamer (HP) hydrogel through self‐assembly mode. This GFs‐HP was a kind of thermosensitive hydrogel that was suitable for orthotopic administration in vivo. Meanwhile, a 3D porous structure of this hydrogel is commonly used to load large amounts of GFs. After single injection of GFs‐HP into the lesioned spinal cord, the sustained release of NGF and bFGF from HP could significantly improve neuronal survival, axon regeneration, reactive astrogliosis suppression and locomotor recovery, when compared with the treatment of free GFs or HP. Moreover, we also revealed that these neuroprotective and neuroregenerative effects of GFs‐HP were likely through activating the phosphatidylinositol 3 kinase and protein kinase B (PI3K/Akt) and mitogen‐activated protein kinase/extracellular signal‐regulated kinase (MAPK/ERK) signalling pathways. Overall, our work will provide an effective therapeutic strategy for SCI repair.     

Injury-induced Cavl-expressing cells at lesion rostral side play major roles in spinal cord regeneration

The extent of cellular heterogeneity involved in neuronal regeneration after spinal cord injury (SCI) remains unclear. Therefore, we established stress-responsive transgenic zebrafish embryos with SCI. As a result, we found an SCI-induced cell population, termed SCI stress-responsive regenerating cells (SrRCs), essential for neuronal regeneration post-SCI. SrRCs were mostly composed of subtypes of radial glia (RGs-SrRCs) and neuron stem/progenitor cells (NSPCs-SrRCs) that are able to differentiate into neurons, and they formed a bridge across the lesion and connected with neighbouring undamaged motor neurons post-SCI. Compared to SrRCs at the caudal side of the SCI site (caudal-SrRCs), rostral-SrRCs participated more actively in neuronal regeneration. After RNA-seq analysis, we discovered that caveolin 1 (cav1) was significantly upregulated in rostral-SrRCs and that cav1 was responsible for the axonal regrowth and regenerative capability of rostral-SrRCs. Collectively, we define a specific SCI-induced cell population, SrRCs, involved in neuronal regeneration, demonstrate that rostral-SrRCs exhibit higher neuronal differentiation capability and prove that cav1 is predominantly expressed in rostral-SrRCs, playing a major role in neuronal regeneration after SCI.     

PI3 Kinase regulation of neural regeneration and muscle hypertrophy after spinal cord injury

Spinal cord injury (SCI) is a serious neurotrauma that can lead to life-long disability; to date, no suitable therapeutic strategy exists. Axons do not regenerate after SCI in adult mammals and loss of skeletal muscle mass occurs very rapidly after SCI. Promotion of neurite growth through improving the extracellular environment allows only a limited degree of axon regeneration. The phosphatidylinositol-3 kinase (PI3K)/Akt pathway and its downstream targets (“mammalian target of rapamycin,” mTOR, and glycogen synthase kinase-3), which regulate cell growth and proliferation in many tissues, have been suggested to play an important role in regulation of the intrinsic axonal regeneration and muscle hypertrophy. This review is focused on recent progress in our understanding of the PI3K pathway in the modulation of axonal regeneration and muscle hypertrophy after SCI.     

AAV-mediated inhibition of ULK1 promotes axonal regeneration in the central nervous system in vitro and in vivo

Axonal damage is an early step in traumatic and neurodegenerative disorders of the central nervous system (CNS). Damaged axons are not able to regenerate sufficiently in the adult mammalian CNS, leading to permanent neurological deficits. Recently, we showed that inhibition of the autophagic protein ULK1 promotes neuroprotection in different models of neurodegeneration. Moreover, we demonstrated previously that axonal protection improves regeneration of lesioned axons. However, whether axonal protection mediated by ULK1 inhibition could also improve axonal regeneration is unknown. Here, we used an adeno-associated viral (AAV) vector to express a dominant-negative form of ULK1 (AAV.ULK1.DN) and investigated its effects on axonal regeneration in the CNS. We show that AAV.ULK1.DN fosters axonal regeneration and enhances neurite outgrowth in vitro. In addition, AAV.ULK1.DN increases neuronal survival and enhances axonal regeneration after optic nerve lesion, and promotes long-term axonal protection after spinal cord injury (SCI) in vivo. Interestingly, AAV.ULK1.DN also increases serotonergic and dopaminergic axon sprouting after SCI. Mechanistically, AAV.ULK1.DN leads to increased ERK1 activation and reduced expression of RhoA and ROCK2. Our findings outline ULK1 as a key regulator of axonal degeneration and regeneration, and define ULK1 as a promising target to promote neuroprotection and regeneration in the CNS.Subject terms: Cell death in the nervous system, Neurodegeneration, Spinal cord injury     

Neurotrophic factor gene delivery supports axonal regeneration after injury

A successful treatment for spinal cord injury (SCI) must include means to induce axonal regeneration and synaptogenesis. Though much research has demonstrated the effectiveness of neurotrophic factors (NFs) in supporting axonal regeneration, systemic delivery of doses sufficient to reach therapeutic concentrations and overcome their short half-lives has caused adverse effects. Local expression of NFs would overcome these limitations. We tested whether local expression of NFs would induce axonal regeneration without adverse effects in two models of neural injury. In a chemical injury model the rat serotonergic system was lesioned with p-chloroamphetamine. When an adenoviral vector carrying the gene for brain-derived neurotrophic factor (BDNF) was injected into the denervated cortex BDNF expressed by the transfected cells induced serotonergic axon reinnervation only in area around the injection site. In a mechanical injury model the cortical spinal tract (CST) in rats was lesioned unilaterally at the level of the hindbrain. Neurotorphin-3 (NT-3) was expressed locally in the spinal cord either by direct injection of an adenoviral vector carrying the gene for NT-3 or by retrograde delivery of the vector from the sciatic nerve. Axons were observed growing from the unlesioned CST across the midline to the denervated side. These data demonstrate that local expression of NFs will induce and support axonal regeneration in a circumscribed area after injury without adverse effects and suggest that a therapy for SCI based upon this strategy may include NF gene delivery.
Acknowledgements:   Supported by NIH grant NS35280 and Mission Connect of the TIRR Foundation.     

Small-molecule-induced Rho-inhibition: NSAIDs after spinal cord injury

Limited axonal plasticity within the central nervous system (CNS) is a major restriction for functional recovery after CNS injury. The small GTPase RhoA is a key molecule of the converging downstream cascade that leads to the inhibition of axonal re-growth. The Rho-pathway integrates growth inhibitory signals derived from extracellular cues, such as chondroitin sulfate proteoglycans, Nogo-A, myelin-associated glycoprotein, oligodendrocyte-myelin glycoprotein, Ephrins and repulsive guidance molecule-A, into the damaged axon. Consequently, the activation of RhoA results in growth cone collapse and finally outgrowth failure. In turn, the inhibition of RhoA-activation blinds the injured axon to its growth inhibitory environment resulting in enhanced axonal sprouting and plasticity. This has been demonstrated in various CNS-injury models for direct RhoA-inhibition and for downstream/upstream blockade of the RhoA-associated pathway. In addition, RhoA-inhibition reduces apoptotic cell death and secondary damage and improves locomotor recovery in clinically relevant models after experimental spinal cord injury (SCI). Unexpectedly, a subset of "small molecules" from the group of non-steroid anti-inflammatory drugs, particularly the FDA-approved ibuprofen, has recently been identified as (1) inhibiting RhoA-activation, (2) enhancing axonal sprouting/regeneration, (3) protecting "tissue at risk" (neuroprotection) and (4) improving motor recovery confined to realistic therapeutical time-frames in clinically relevant SCI models. Here, we survey the effect of small-molecule-induced RhoA-inhibition on axonal plasticity and neurofunctional outcome in CNS injury paradigms. Furthermore, we discuss the body of preclinical evidence for a possible clinical translation with a focus on ibuprofen and illustrate putative risks and benefits for the treatment of acute SCI.     

Polydatin promotes the neuronal differentiation of bone marrow mesenchymal stem cells in vitro and in vivo: Involvement of Nrf2 signalling pathway

Bone marrow mesenchymal stem cell (BMSC) transplantation represents a promising repair strategy following spinal cord injury (SCI), although the therapeutic effects are minimal due to their limited neural differentiation potential. Polydatin (PD), a key component of the Chinese herb Polygonum cuspidatum, exerts significant neuroprotective effects in various central nervous system disorders and protects BMSCs against oxidative injury. However, the effect of PD on the neuronal differentiation of BMSCs, and the underlying mechanisms remain inadequately understood. In this study, we induced neuronal differentiation of BMSCs in the presence of PD, and analysed the Nrf2 signalling and neuronal differentiation markers using routine molecular assays. We also established an in vivo model of SCI and assessed the locomotor function of the mice through hindlimb movements and electrophysiological measurements. Finally, tissue regeneration was evaluated by H&E staining, Nissl staining and transmission electron microscopy. PD (30 μmol/L) markedly facilitated BMSC differentiation into neuron‐like cells by activating the Nrf2 pathway and increased the expression of neuronal markers in the transplanted BMSCs at the injured spinal cord sites. Furthermore, compared with either monotherapy, the combination of PD and BMSC transplantation promoted axonal rehabilitation, attenuated glial scar formation and promoted axonal generation across the glial scar, thereby enhancing recovery of hindlimb locomotor function. Taken together, PD augments the neuronal differentiation of BMSCs via Nrf2 activation and improves functional recovery, indicating a promising new therapeutic approach against SCI.     

Neurotrophic factor gene delivery supports axonal regeneration after injury

A successful treatment for spinal cord injury (SCI) must include means to induce axonal regeneration and synaptogenesis. Though much research has demonstrated the effectiveness of neurotrophic factors (NFs) in supporting axonal regeneration, systemic delivery of doses sufficient to reach therapeutic concentrations and overcome their short half‐lives has caused adverse effects. Local expression of NFs would overcome these limitations. We tested whether local expression of NFs would induce axonal regeneration without adverse effects in two models of neural injury. In a chemical injury model the rat serotonergic system was lesioned with p‐chloroamphetamine. When an adenoviral vector carrying the gene for brain‐derived neurotrophic factor (BDNF) was injected into the denervated cortex BDNF expressed by the transfected cells induced serotonergic axon reinnervation only in area around the injection site. In a mechanical injury model the cortical spinal tract (CST) in rats was lesioned unilaterally at the level of the hindbrain. Neurotorphin‐3 (NT‐3) was expressed locally in the spinal cord either by direct injection of an adenoviral vector carrying the gene for NT‐3 or by retrograde delivery of the vector from the sciatic nerve. Axons were observed growing from the unlesioned CST across the midline to the denervated side. These data demonstrate that local expression of NFs will induce and support axonal regeneration in a circumscribed area after injury without adverse effects and suggest that a therapy for SCI based upon this strategy may include NF gene delivery. Acknowledgements: Supported by NIH grant NS35280 and Mission Connect of the TIRR Foundation.     

A selective Sema3A inhibitor enhances regenerative responses and functional recovery of the injured spinal cord

Axons in the adult mammalian central nervous system (CNS) exhibit little regeneration after injury. It has been suggested that several axonal growth inhibitors prevent CNS axonal regeneration. Recent research has demonstrated that semaphorin3A (Sema3A) is one of the major inhibitors of axonal regeneration. We identified a strong and selective inhibitor of Sema3A, SM-216289, from the fermentation broth of a fungal strain. To examine the effect of SM-216289 in vivo, we transected the spinal cord of adult rats and administered SM-216289 into the lesion site for 4 weeks. Rats treated with SM-216289 showed substantially enhanced regeneration and/or preservation of injured axons, robust Schwann cell-mediated myelination and axonal regeneration in the lesion site, appreciable decreases in apoptotic cell number and marked enhancement of angiogenesis, resulting in considerably better functional recovery. Thus, Sema3A is essential for the inhibition of axonal regeneration and other regenerative responses after spinal cord injury (SCI). These results support the possibility of using Sema3A inhibitors in the treatment of human SCI.