许旺细胞外泌体减少脊髓损伤区血管生成和瘢痕形成促进神经修复

Schwann cell-derived exosomes attenuate angiogenesis and fibrotic scar formation and promote nerve repair

背景:脊髓损伤可以导致轴突严重受损和神经元死亡,从而导致运动和/或感觉功能永久丧失。目前对于脊髓损伤的治疗手段仍然十分局限,外泌体作为一种非细胞疗法,因其强大的生物学活性而备受关注,有可能成为脊髓损伤的一种新兴治疗方案。目的:观察许旺细胞来源外泌体对小鼠脊髓损伤后神经轴突的修复作用。方法:将30只C57小鼠随机分成假手术组、许旺细胞来源外泌体组和PBS对照组,每组10只,对许旺细胞来源外泌体组和PBS对照组小鼠进行脊髓钳夹损伤,损伤24 h后,许旺细胞来源外泌体组小鼠尾静脉注射许旺细胞来源外泌体,PBS对照组小鼠尾静脉注射PBS,每周3次,持续4周,每次每只注射25μL (0.1 g/L)。最后一次注射后24 h后处死小鼠,取出脊柱并分离出损伤部位上下各1 cm范围内的脊髓进行固定、脱水、包埋和切片。免疫荧光染色观察损伤区域CD31阳性血管内皮细胞和FSP1阳性成纤维细胞的募集,以及NF200阳性神经轴突存活情况。结果与结论:与PBS对照组相比,许旺细胞来源外泌体组小鼠损伤区域中CD31阳性细胞数量减少(P <0.01),FSP1阳性细胞数量减少(P <0.05),以及NF200阳性轴突数量增加(P <0.01)。结果表明,许旺细胞来源外泌体可以减少脊髓损伤区域内血管生成和瘢痕形成,并促进神经轴突的修复。

BACKGROUND:Spinal cord injury can result in severe damage to axons and neuronal death,leading to permanent loss of motor and/or sensory function.At present,the treatment methods for spinal cord injury are still very limited.As a non-cellular therapy,exosomes have attracted much attention due to their powerful biological activities,and have the potential to become an emerging treatment option for spinal cord injury.OBJECTIVE:To investigate the role of Schwann cell-derived exosomes on nerve axons a?ter spinal cord injury in mice.METHODS:Thirty C57 mice were randomly divided into sham group,Schwann cell-derived exosome treatment group and PBS control group(n=10 per group).The clamp injury was conducted on Schwann cell-derived exosome treatment group and PBS control group.A?ter injury for 24 hours,the mice in the Schwann cell-derived exosome treatment group were injected with exosomes derived from Schwann cells via the caudal vein,and the mice in the PBS control group were injected with PBS via the caudal vein,three times a week for 4 weeks,25 μL/mice(0.1 g/L) each time.Mice were sacrificed 24 hours a?ter the last injection.A?ter removing the spine,tissue one centimeter above and below the injury site of the spinal cord was isolated for fixation,dehydration,embedding and sectioning.The recruitment of CD31-positive vascular endothelial cells and FSP1-positive fibroblasts in the injured area,as well as the survival of NF200 positive axons was observed by immunofluorescence staining.RESULTS AND CONCLUSION:Compared with the PBS control group,the number of CD31-positive endothelial cells was decreased(P < 0.01) and the number of FSP1-positive fibroblasts in the injured area was decreased in the mice treated with Schwann cell-derived exosomes(P < 0.05).The number of NF200-positive axons was increased in the Schwann cell-derived exosome treatment group compared with the PBS control group(P < 0.01).These results suggest that Schwann cell-derived exosomes can reduce the recruitment of angiogenesis and scar formation cells in the area a?ter spinal cord injury and promote the recovery of nerve axons.