神经干细胞复合功能化注射型胶原支架用于脊髓损伤的修复及实时监测

Spinal cord injury (SCI) is a serious central nervous system (CNS) trauma that could hardly be successful repaired. Recently, strategy of combining scaffolds with neural stem cells (NSCs) offers a promising approach of SCI treatment. However, the main challenge for NSC-mediated repair is lack of favorable environment to direct NPCs differentiation towards neurons rather than glial cells. The myelin associated inhibitors and EGFR activity at the lesion site have been demonstrated to promote NSC differentiation into glial lineage. To promote axonal regeneration after injuries in CNS, an environment suitable for NSC growth and differentiation is critical. Hence, we propose here that using thermo-sensitive collagen-based polymer as scaffolds combined with NSCs for axonal regeneration, which can be directly injected to the damage site. To enhance neurotrophic effects, nerve growth factor and EGFR inhibitor modified Fe3O4 nanoparticles are explored to functionalize the injectable collagen scaffold for NSC implantation. The synthesized scaffold with magnetic resonance imaging (MRI) functionality provides proper microenvironment for NSC growth and differentiation, as well as offers real-time status of the implanted scaffold in vivo using MRI. The present work will provides an insight into a rational design of new injectable scaffolds with growth factor and MRI functionality, and therefore creating appropriate microenvironment for NSC regulation, which will provide valuable information for clinical use of NSCs.

脊髓损伤是一种难修复治疗的中枢神经系统疾病。目前，干细胞治疗被认为是解决这一难题的新策略。但是，移植后干细胞的存活和向神经元分化容易因损伤病理微环境而受到抑制。因此，如何构建适宜的移植微环境是提高神经干细胞在体内存活、增殖和分化能力的关键。本项目拟制备可注射的基于胶原的温敏性水凝胶材料，复合神经干细胞后可直接注射至损伤部位形成支架。同时，将材料与生长因子和神经分化抑制因子拮抗剂修饰的Fe3O4纳米粒子结合，构建具有磁共振成像的功能支架材料，期望利用生长因子和阻断神经分化抑制因子的EGFR抗体提供利于神经再生的微环境，促进神经损伤修复。在此基础上，利用磁共振成像技术实时提供支架在体内的状态信息。通过本项目的实施为发展利用适宜的微环境和神经干细胞治疗脊髓损伤提供理论依据和技术支持。

成年个体脊髓损伤后很难自发再生修复，本项目希望通过组织工程支架的手段营造出适宜干细胞生长分化以及神经再生的微环境，进而促进脊髓损伤区轴突再生及功能恢复。根据项目书我们合成了可注射温敏性胶原和3D生物打印的基于可见光交联的可降解高分子水凝胶；制备纳米载体用于负载缓释小分子及生长因子，构建具有利于干细胞生长分化微环境的功能化三维支架。实验结果表明，我们获得的功能化三维水凝胶支架具有高效负载效率及长期缓控释放小分子或生长因子的功能，为移植的干细胞提供了适宜的生长及分化微环境，促进支架中干细胞生长分化。将该功能化三维水凝胶支架移植至鼠脊髓全横损伤区域，可以有效促进神经损伤修复，降低损伤区炎症因子分泌，促进轴突再生，为功能生物材料的进一步临床应用奠定基础。依托本项目，我们已发表论文6篇，其中影响因子大于5 的论文3篇；参与编撰图书章节2章，参加国际学术会议并作报告6次。