可调控降解CSPGs的藻酸盐3D微管道支架的构建及其对慢性脊髓损伤的修复作用研究

Reactive glial scarring and cavitation in the lesion are the typical changes of traumatic spinal cord injury (TSCI) in chronic phase, which are great hurdles impeding axonal growth. Our previous studies indicated that the alginate-hydrogel scaffold (AHS) with linear capillaries had great biological compatibility with the spinal cord. Besides, engraftment of alginate scaffold into the lesion of TSCI in the early stage was able to repair the spinal cord by restoring the continuity and providing guidance for axonal regeneration in a nearly physical and linear pattern. Regenerating axons, however, were confined in the glial scar around the graft after extending through the lesion and lost growth capacity gradually in previous studies，which leads to the failure of synaptic formation with downstream neurons. Most recent researches illuminated that chondroitin sulfate proteoglycans (CSPGs) within the scars were the major factors inhibiting axonal regeneration via activating various receptors. Subsequently, strategies targeted refilling of the cavity and degradation CSPGs in the glial scar would potentially facilitate further axonal growth and functional improvement..To optimize the therapeutic efficacy of AHS and avoid the side effects of CSPGs overdegradation on spinal cord tissue, the present project is designed to establish a viral vector (Tet-on-ChABC) to strictly control CSPGs digestion, exploring the therapeutic effects of AHS in combination with regulated CSPGs digestion in axonal plasticity and functional recovery after chronic TSCI. The results from this novel study are highly expected to provide effective approaches and theoretical supports for upcoming treatment of chronic TSCI.

囊腔和胶质瘢痕形成是影响慢性创伤性脊髓损伤（TSCI）后轴突再生的主要因素。申请者前期研究发现含有线性微管道的藻酸盐凝胶支架(AHS)与脊髓组织有良好的生物相容性，能有效修复囊腔并介导轴突呈接近生理状态的线性生长。但是，新生轴突“穿过”囊腔后局限在周围胶质瘢痕中而失去再生潜能，不能与下游神经元建立突触联系。近年来研究认为胶质瘢痕中硫酸软骨素蛋白聚糖(CSPGs)是抑制轴突再生的主要因子之一。因此，AHS移植联合可调控降解CSPGs的治疗措施，有望提高AHS的治疗效率，同时避免CSPGs过度降解对正常脊髓组织的不利影响，促进伤后轴突重塑和功能恢复。本项目拟在前期基础上，优化移植策略并利用基因工程技术构建可调控降解CSPGs的基因载体，研究AHS移植和可调控降解CSPGs的联合治疗措施对慢性TSCI后轴突再生和功能重建作用，为慢性TSCI的治疗提供安全有效的新途径和理论依据。

慢性创伤性脊髓损伤（TSCI）发病率高，治疗难度大，治疗效果差。囊腔和胶质瘢痕形成是影响TSCI后轴突再生的主要因素。申请者前期研究发现含有线性微管道的藻酸盐凝胶支架(AHS)与脊髓组织有良好的生物相容性，能有效修复囊腔并介导轴突呈接近生理状态的线性生长。但是，新生轴突“穿过”囊腔后局限在周围胶质瘢痕中而失去再生潜能，不能与下游神经元建立突触联系。本研究中，申请者以慢性TSCI的大鼠为动物模型，采用显微手术切除瘢痕后移植AHS的方法，修复脊髓的连续性并促进一定数量的轴突再生和功能恢复，验证了AHS对TSCI修复的有效性。为进一步提高移植效率和安全性，项目组采用AHS联合可调控降解胶质瘢痕中硫酸软骨素蛋白聚糖(CSPGs)的方法，进一步促进了轴突再生进入正常脊髓组织，恢复肢体功能。此外，项目组还将AHS荷载脊髓神经干细胞（NSPCs）移植到伤灶中，可见NSPCs分化成神经元，在受体脊髓神经元之间充当“桥接”的作用，重建神经环路。本研究充分验证了AHS对慢性TSCI的修复作用，并为AHS作为其他治疗手段的载体奠定了基础，为慢性TSCI的治疗提供安全有效的新途径和理论依据。

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