Chen Jian, Wu Junfang, Apostolova Ivayla, Skup Malgorzata, Irintchev Andrey, Kügler Sebastian, Schachner Melitta
W. M. Keck Center for Collaborative Neuroscience, Department of Cell Biology and Neuroscience, Rutgers the State University of New Jersey, Piscataway, NJ 08854, USA.
Brain. 2007 Apr;130(Pt 4):954-69. doi: 10.1093/brain/awm049.
Paucity of permissive molecules and abundance of inhibitory molecules in the injured spinal cord of adult mammals prevent axons from successful regeneration and, thus, contribute to the failure of functional recovery. Using an adeno-associated viral (AAV) vector, we expressed the regeneration-promoting cell adhesion molecule L1 in both neurons and glia in the lesioned spinal cord of adult mice. Exogenous L1, detectable already 1 week after thoracic spinal cord compression and immediate vector injection, was expressed at high levels up to 5 weeks, the longest time-period studied. Dissemination of L1-transduced cells throughout the spinal cord was wide, spanning over more than 10 mm rostral and 10 mm caudal to the lesion scar. L1 was not detectable in the fibronectin-positive lesion core. L1 overexpression led to improved stepping abilities and muscle coordination during ground locomotion over a 5-week observation period. Superior functional improvement was associated with enhanced reinnervation of the lumbar spinal cord by 5-HT axons. Corticospinal tract axons did not regrow beyond the lesion scar but extended distally into closer proximity to the injury site in AAV-L1-treated compared with control mice. The expression of the neurite outgrowth-inhibitory chondroitin sulphate proteoglycan NG2 was decreased in AAV-L1-treated spinal cords, along with reduction of the reactive astroglial marker GFAP. In vitro experiments confirmed that L1 inhibits astrocyte proliferation, migration, process extension and GFAP expression. Analyses of intracellular signalling indicated that exogenous L1 activates diverse cascades in neurons and glia. Thus, AAV-mediated L1 overexpression appears to be a potent means to favourably modify the local environment in the injured spinal cord and promote regeneration. Our study demonstrates a clinically feasible approach of promising potential.
成年哺乳动物脊髓损伤后，允许性分子匮乏而抑制性分子丰富，这会阻止轴突成功再生，进而导致功能恢复失败。我们使用腺相关病毒（AAV）载体，在成年小鼠脊髓损伤部位的神经元和胶质细胞中均表达了促进再生的细胞粘附分子L1。外源性L1在胸段脊髓压迫并立即注射载体后1周即可检测到，在长达5周（研究的最长时间段）内均高水平表达。L1转导细胞在整个脊髓中的扩散范围很广，跨越损伤瘢痕头端超过10 mm和尾端超过10 mm的区域。在纤连蛋白阳性的损伤核心中未检测到L1。在5周的观察期内，L1过表达导致地面运动时的步行动能和肌肉协调性得到改善。 superior功能改善与5-HT轴突对腰段脊髓的再支配增强有关。与对照小鼠相比，在接受AAV-L1治疗的小鼠中，皮质脊髓束轴突未生长到损伤瘢痕之外，但向远端延伸至更靠近损伤部位。在接受AAV-L1治疗的脊髓中，神经突生长抑制性硫酸软骨素蛋白聚糖NG2的表达降低，同时反应性星形胶质细胞标记物GFAP也减少。体外实验证实，L1可抑制星形胶质细胞的增殖、迁移、突起延伸和GFAP表达。细胞内信号分析表明，外源性L1可激活神经元和胶质细胞中的多种信号级联反应。因此，AAV介导的L1过表达似乎是一种有效手段，可有利地改变脊髓损伤部位的局部环境并促进再生。我们的研究证明了一种具有潜在前景的临床可行方法。
