Elsayed Heba, Faroni Alessandro, Ashraf Mohammad R, Osuji Judith, Wunderley Lydia, Zhang Ling, Elsobky Hesham, Mansour Mohamed, Zidan Ashraf S, Reid Adam J
Blond McIndoe Laboratories, Division of Cell Matrix Biology and Regenerative Medicine, School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, United Kingdom.
Department of Neurosurgery, Mansoura University Hospitals, Mansoura, Egypt.
Front Bioeng Biotechnol. 2020 Jul 10;8:784. doi: 10.3389/fbioe.2020.00784. eCollection 2020.
Following peripheral nerve injury, a sequence of events termed Wallerian degeneration (WD) takes place at the distal stump in order to allow the regenerating axons to grow back toward the target organs. Schwann cells (SCs) play a lead role in this by initiating the inflammatory response attracting macrophages and immune cells, as well as producing neurotrophic signals that are essential for nerve regeneration. The majority of existing research has focused on tools to improve regeneration, overlooking the critical degeneration phase. This is also due to the lack of models recapitulating the features of WD. In particular, to understand the initial SC response following injury, and to investigate potential interventions, a model that isolates the nerve from other systemic influences is required. Stem cell intervention has been extensively studied as a potential therapeutic intervention to augment regeneration; however, data regarding their role in WD is lacking. Thus, in this study we describe an model using rat sciatic nerve explants degenerating up to 14 days. Characterisation of this model was performed by gene and protein expression for key markers of WD, in addition to immunohistochemical analysis and electron microscopy. We found changes in keeping with WD : upregulation of repair program protein CJUN, downregulation of myelin protein genes and subsequent disorganisation and breakdown of myelin structure. As a means of testing the effects of stem cell intervention on WD we established indirect co-cultures of human adipose-derived mesenchymal stem cells (AD-MSC) with the degenerating nerve explants. The stem cell intervention potentiated neurotrophic factors and C expression. We conclude that our model shares the main features of WD, and we provide proof of principle on its effectiveness to study experimental approaches for nerve regeneration focused on the events happening during WD.
周围神经损伤后，远端残端会发生一系列称为沃勒变性（WD）的事件，以使再生轴突能够向靶器官生长回去。雪旺细胞（SCs）在其中起主导作用，它们启动炎症反应以吸引巨噬细胞和免疫细胞，并产生对神经再生至关重要的神经营养信号。现有的大多数研究都集中在改善再生的工具上，而忽略了关键的变性阶段。这也是由于缺乏能够概括WD特征的模型。特别是，为了了解损伤后雪旺细胞的初始反应，并研究潜在的干预措施，需要一个将神经与其他全身影响隔离开来的模型。干细胞干预作为一种增强再生的潜在治疗干预措施已得到广泛研究；然而，关于它们在WD中的作用的数据却很缺乏。因此，在本研究中，我们描述了一种使用大鼠坐骨神经外植体退变长达14天的模型。除了免疫组织化学分析和电子显微镜检查外，还通过对WD关键标志物的基因和蛋白质表达对该模型进行了表征。我们发现了与WD一致的变化：修复程序蛋白CJUN上调，髓磷脂蛋白基因下调，随后髓磷脂结构紊乱和破坏。作为测试干细胞干预对WD影响的一种方法，我们建立了人脂肪间充质干细胞（AD-MSC）与退变神经外植体的间接共培养。干细胞干预增强了神经营养因子和C的表达。我们得出结论，我们的模型具有WD的主要特征，并且我们为其在研究专注于WD期间发生的事件的神经再生实验方法的有效性提供了原理证明。
