Xie Jing, Huo Shujia, Li Yijian, Dai Jiaman, Xu Haiwei, Yin Zheng Qin
Cell Transplant. 2017 Jun 9;26(6):967-982. doi: 10.3727/096368917X694994. Epub 2017 Feb 9.
Retinal regeneration and self-repair, whether in response to injury or degenerative disease, are severely impeded by glial scar formation by Müller cells (specialized retinal macroglia). We have previously demonstrated that the activation of Müller cells and gliosis in the degenerative retina are significantly suppressed by the subretinal transplantation of a mixture of olfactory ensheathing cells (OECs) and olfactory nerve fibroblasts. However, the underlying molecular mechanism has remained elusive. Here we transplanted purified rat OECs into the subretinal space of pigmented Royal College of Surgeons (RCS) rats, a classic rodent model of retinal degeneration. Using behavioral testing and electroretinography, we confirmed that the grafted OECs preserved the visual function of rats for 8 weeks, relative to vehicle controls (phosphate-buffered saline). Histological evaluation of outer nuclear layer thickness and composition demonstrated that more photoreceptors and ON-bipolar cells were preserved in the retinas of OEC-treated RCS rats than in controls. The grafted OECs migrated into the outer plexiform layer, inner nuclear layer, and inner plexiform layer. They interacted directly with Müller cells in the retina of RCS rats, in three distinct patterns, and secreted matrix metalloproteinases 2 and 3. Previous studies have demonstrated that rat OECs express delta-like ligand (DLL), while Müller cells express Notch3, the receptor for DLL. Here we found that the grafted OECs significantly decreased the expression, by retinal cells, of Notch signaling pathway components (including Notch3, Notch4, DLL1, DLL4, Jagged1, Hes1, and Hes5) 2 weeks after the cell transplantation and that this effect persisted for a further 2 weeks. Based on these findings, we suggest that transplanted OECs inhibit the activation of Müller cells and the associated gliosis, at least partly through suppression of the Notch pathway.
视网膜的再生和自我修复，无论是对损伤还是退行性疾病的反应，都受到穆勒细胞（视网膜特化的大胶质细胞）形成的胶质瘢痕的严重阻碍。我们之前已经证明，在退行性视网膜中，穆勒细胞的激活和胶质化通过视网膜下移植嗅鞘细胞（OECs）和嗅神经成纤维细胞的混合物得到显著抑制。然而，其潜在的分子机制仍然不清楚。在这里，我们将纯化的大鼠OECs移植到色素性皇家外科学院（RCS）大鼠的视网膜下间隙，这是一种经典的视网膜退行性啮齿动物模型。通过行为测试和视网膜电图，我们证实，相对于载体对照（磷酸盐缓冲盐水），移植的OECs在8周内维持了大鼠的视觉功能。对内核层厚度和组成的组织学评估表明，与对照组相比，接受OEC治疗的RCS大鼠视网膜中保留了更多的光感受器和ON双极细胞。移植的OECs迁移到外网状层、内核层和内网状层。它们以三种不同的模式与RCS大鼠视网膜中的穆勒细胞直接相互作用，并分泌基质金属蛋白酶2和3。先前的研究表明，大鼠OECs表达Delta样配体（DLL），而穆勒细胞表达DLL的受体Notch3。在这里，我们发现，细胞移植后2周，移植的OECs显著降低了视网膜细胞中Notch信号通路成分（包括Notch3、Notch4、DLL1、DLL4、Jagged1、Hes1和Hes5）的表达，并且这种作用持续了另外2周。基于这些发现，我们认为移植的OECs至少部分通过抑制Notch通路来抑制穆勒细胞的激活和相关的胶质化。
