Fan Caixia, Li Xing, Xiao Zhifeng, Zhao Yannan, Liang Hui, Wang Bin, Han Sufang, Li Xiaoran, Xu Bai, Wang Nuo, Liu Sumei, Xue Weiwei, Dai Jianwu
Key Laboratory for Nano-Bio Interface Research, Division of Nanobiomedicine, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China; University of Chinese Academy of Sciences, Beijing 100190, China.
State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
Acta Biomater. 2017 Mar 15;51:304-316. doi: 10.1016/j.actbio.2017.01.009. Epub 2017 Jan 6.
Due to irreversible neuronal loss and glial scar deposition, spinal cord injury (SCI) ultimately results in permanent neurological dysfunction. Neuronal regeneration of neural stem cells (NSCs) residing in the spinal cord could be an ideal strategy for replenishing the lost neurons and restore function. However, many myelin-associated inhibitors in the SCI microenvironment limit the ability of spinal cord NSCs to regenerate into neurons. Here, a linearly ordered collagen scaffold was used to prevent scar deposition, guide nerve regeneration and carry drugs to neutralize the inhibitory molecules. A collagen-binding EGFR antibody Fab fragment, CBD-Fab, was constructed to neutralize the myelin inhibitory molecules, which was demonstrated to promote neuronal differentiation and neurite outgrowth under myelin in vitro. This fragment could also specifically bind to the collagen and undergo sustained release from collagen scaffold. Then, the scaffolds modified with CBD-Fab were transplanted into an acute rat SCI model. The robust neurogenesis of endogenous injury-activated NSCs was observed, and these NSCs could not only differentiate into neurons but further mature into functional neurons to reconnect the injured gap. The results indicated that the modified collagen scaffold could be an ideal candidate for spinal cord regeneration after acute SCI.
A linearly ordered collagen scaffold was specifically modified with collagen-binding EGFR antibody, allowed for sustained release of this EGFR neutralizing factor, to block the myelin associated inhibitory molecules and guide spinal cord regeneration along its linear fibers. Dorsal root ganglion neurons and neural stem cells induced by CBD-Fab exhibited enhanced neurite outgrowth and neuronal differentiation rate under myelin in vitro. Transplantation of the modified collagen scaffold with moderate EGFR neutralizing proteins showed greatest advantage on endogenous neurogenesis of injury-activated neural stem cells for acute spinal cord injury repair.
由于不可逆的神经元丢失和胶质瘢痕沉积，脊髓损伤（SCI）最终导致永久性神经功能障碍。脊髓中神经干细胞（NSCs）的神经元再生可能是补充丢失神经元并恢复功能的理想策略。然而，SCI微环境中的许多髓磷脂相关抑制剂限制了脊髓神经干细胞再生为神经元的能力。在此，使用线性排列的胶原蛋白支架来防止瘢痕沉积、引导神经再生并携带药物以中和抑制分子。构建了一种胶原蛋白结合EGFR抗体Fab片段CBD-Fab来中和髓磷脂抑制分子，体外实验证明其能促进髓磷脂环境下的神经元分化和神经突生长。该片段还能特异性结合胶原蛋白并从胶原蛋白支架中持续释放。然后，将用CBD-Fab修饰的支架移植到急性大鼠SCI模型中。观察到内源性损伤激活的神经干细胞有强劲的神经发生，这些神经干细胞不仅能分化为神经元，还能进一步成熟为功能性神经元以重新连接受损间隙。结果表明，修饰后的胶原蛋白支架可能是急性SCI后脊髓再生的理想候选物。
用胶原蛋白结合EGFR抗体对线性排列的胶原蛋白支架进行特异性修饰，使这种EGFR中和因子持续释放，以阻断髓磷脂相关抑制分子并沿其线性纤维引导脊髓再生。CBD-Fab诱导的背根神经节神经元和神经干细胞在体外髓磷脂环境下表现出增强的神经突生长和神经元分化率。移植含有适度EGFR中和蛋白的修饰胶原蛋白支架对急性脊髓损伤修复中损伤激活的神经干细胞的内源性神经发生具有最大优势。
