SHH是调控神经系统发育的关键形态发生因子，既能促进NSCs增殖又能诱导NSCs分化。然而，其双重调节的分子机制仍不太清楚。根据文献报道和前期的预实验结果，我们推测：游离SHH可能通过经典Patched-Smoothened-Gli通路促进NSCs增殖，而交联于细胞外基质的SHH多聚体将激活非经典BOC-SFKs通路并协同Integrins-FAK通路诱导NSCs分化。本项目将TG2和SHH基因修饰的EMSCs共同种植于Fibrin胶，通过EMSCs持续分泌交联剂TG2和生物活性因子SHH，构建自分泌、自交联的SHH-Fibrin生物活性支架；观察支架对大鼠脊髓NSCs命运的影响，并探讨其分子机制；将转基因EMSCs/Fibrinogen混合溶胶注入脊髓损伤部位，原位自组装成SHH-Fibrin支架，评价其促进内源NSCs有序增殖、迁移和分化，建立神经接力网络修复脊髓损伤的效果。

As a well-known morphogen, SHH plays an important role in regulating the development of nervous system. It can promote NSCs’ proliferation and induce their differentiation as well. However, the molecular mechanisms of SHH’s dual effects are yet to be clarified. Based on previous reports and our preliminary experimental data, we hypothesize that the free SHH may promote the proliferation of NSCs via the classical signaling pathway (Patched-Smoothened-Gli), while SHH multimers, cross-linked to extracellular matrix, can activate the non-canonical BOC-SFKs pathway and Integrins-FAK pathway to induce the differentiation of NSCs. This project focuses on using TG2 and SHH genes to modify the nasal mucosa-derived EMSCs which will be cultured in the fibrin glue. These EMSCs will secrete the cross-linker TG2 and bioactive factor SHH in the fibrin. Thus forming a novel, bioactive SHH-Fibrin scaffold featuring autocrine and self-assembly. The outcome of the investigations will reveal the effects exerted by this SHH-Fibrin scaffold in regulating the embryonic rat spinal cord NSCs as well as the underlying molecular mechanisms. Afterwards, the transgenic EMSCs/Fibrinogen hybrid gel will be injected into the spinal cord lesions to form SHH-Fibrin self-assembly scaffolds in situ, followed by the evaluation of the scaffolds’ impact on promoting proliferation, migration and differentiation of the endogenous NSCs, and their effects on the establishment of neural relay network to repair the spinal cord injury. This project provides a new strategy for the application of stem cells/scaffold which could offer a great potential in improving the repairing of the injured spinal cord.