Kostyk S K, Popovich P G, Stokes B T, Wei P, Jakeman L B
Department of Neurology, The Ohio State University Medical Center, Columbus, OH 43210, USA.
Neuroscience. 2008 Oct 15;156(3):498-514. doi: 10.1016/j.neuroscience.2008.08.013. Epub 2008 Aug 19.
Spinal cord injury (SCI) in mammals leads to a robust inflammatory response followed by the formation of a glial and connective tissue scar that comprises a barrier to axonal regeneration. The inbred MRL/MpJ mouse strain exhibits reduced inflammation after peripheral injury and shows true regeneration without tissue scar formation following an ear punch wound. We hypothesized that following SCI, the unique genetic wound healing traits of this strain would result in reduced glial and connective tissue scar formation, increased axonal growth, and improved functional recovery. Adult MRL/MpJ and C57BL/6J mice were subjected to a mid-thoracic spinal contusion and the distribution of axon profiles and selected cellular and extracellular matrix components was compared at 1, 2, 4 and 6 weeks post-injury. Recovery of hind-limb locomotor function was assessed over the same time period. The MRL/MpJ mice exhibited robust axon growth within the lesion, beginning at 4 weeks post-injury. This growth was accompanied by reduced macrophage staining at 1, 2, 4 and 6 weeks post-injury, decreased chondroitin sulfate proteoglycan staining at 1-2 weeks and increased laminin staining throughout the lesion at 2-6 weeks post-injury. Paradoxically, the extent of locomotor recovery was impaired in the MRL/MpJ mice. Close examination of the chronic lesion site revealed evidence of ongoing degeneration both within and surrounding the lesion site. Thus, the regenerative genetic wound healing traits of the MRL/MpJ mice contribute to the evolution of a lesion environment that supports enhanced axon growth after SCI. However, this response occurs at the expense of meaningful functional recovery.
哺乳动物的脊髓损伤(SCI)会引发强烈的炎症反应,随后形成胶质和结缔组织瘢痕,该瘢痕构成了轴突再生的障碍。近交系MRL/MpJ小鼠品系在周围损伤后炎症反应减轻,并且在耳部打孔创伤后能实现真正的再生,且无组织瘢痕形成。我们推测,脊髓损伤后,该品系独特的基因伤口愈合特性将导致胶质和结缔组织瘢痕形成减少、轴突生长增加以及功能恢复改善。成年MRL/MpJ和C57BL/6J小鼠接受胸中段脊髓挫伤,并在损伤后1、2、4和6周比较轴突轮廓以及选定的细胞和细胞外基质成分的分布。在同一时间段内评估后肢运动功能的恢复情况。MRL/MpJ小鼠在损伤后4周开始在损伤部位出现强劲的轴突生长。这种生长伴随着损伤后1、2、4和6周巨噬细胞染色减少,损伤后1 - 2周硫酸软骨素蛋白聚糖染色减少,以及损伤后2 - 6周整个损伤部位层粘连蛋白染色增加。矛盾的是,MRL/MpJ小鼠的运动恢复程度受损。对慢性损伤部位的仔细检查发现损伤部位及其周围存在持续退化的迹象。因此,MRL/MpJ小鼠的再生性基因伤口愈合特性有助于形成一种损伤环境,该环境支持脊髓损伤后轴突生长增强。然而,这种反应是以有意义的功能恢复为代价的。