基于3D仿生半月板支架的TGF-β1调控BMSCs促进半月板再生修复的机制研究

半月板损伤是膝关节常见的软骨疾病，往往需切除半月板治疗，虽可缓解部分症状，但半月板切除会导致膝关节严重功能障碍。为此，本项目组模拟天然半月板结构，采用3D打印技术，构建PCL复合凝胶仿生支架，成功诱导了半月板再生修复，但机制不明。继续研究发现其中骨髓间充质干细胞（BMSCs）外泌体M2型巨噬细胞相关因子TGF-β1高表达，且能促进软骨细胞迁移和分化。由此，我们提出其机制假说：基于3D仿生PCL复合半月板支架，通过诱导BMSCs外泌体TGF-β1表达，调控M2型巨噬细胞极化，诱导软骨细胞形成，促进半月板软骨再生修复。本申请项目拟过表达和沉默BMSCs细胞TGF-β1后与PCL支架共培养，分析其外泌体及M2型巨噬细胞极化等改变；借助过表达和沉默TGF-β1的BMSCs复合半月板支架，探讨基于仿生支架的TGF-β1调控BMSCs促进半月板再生修复的机制，为临床治疗提供新切入点。

Meniscal injury is one of the most common knee joint diseases and often needs to remove during the treatment, which can lead to the mechanical imbalance and serious dysfunction of the knee joint. Our prior researches simulated the natural meniscus structure, constructed the scaffold of PCL composite fibrin gel by 3D printing technology, and successfully induced the regeneration and repair of meniscus. In order to explore the mechanism, we using qRT-PCR and found that the exosomes of bone marrow mesenchymal stem cells (BMSCs) based on meniscus scaffold can significantly induce the expression of TGF-β1 in M2 macrophages, and promote the migration and regeneration of chondrocytes. Therefore, we hypothesize that BMSCs derived exon derived from PCL composite fibrin gel 3D biomimetic meniscus scaffold can induce the expression of TGF-β1, regulate the polarization of M2 macrophages, and promote the regeneration and repair of meniscal chondrocytes. This project tries to overexpress and knockdown TGF-β1 in BMSCs, and co-culture with PCL scaffolds. The changes of exosomes and macrophage polarization were analyzed to elucidate the signal pathway regulated by TGF-β1. To observe the role of BMSCs，overexpression and silencing of TGF-β1 were implanted into the exosomes with meniscus scaffolds. We will demonstrate the molecular mechanism of TGF-β1 participating in the process of meniscus chondrocyte regeneration and repair and PCL scaffolds promoting meniscus regeneration and repair. The present study is expected to provide a new entry point for clinical treatment.