软骨终板（CEP）退变是椎间盘退变（IVDD）的重要原因，其特征是软骨细胞死亡。越来越多的证据表明，动力相关蛋白 1 (Drp1) 介导的线粒体分裂和功能障碍会导致 CEP 变性和 IVDD 过程中的细胞凋亡。外泌体是治疗许多疾病的有前途的药物，包括骨质疏松症、骨肉瘤、骨关节炎和 IVDD。尽管外泌体在药物递送方面取得了巨大成功，但外泌体的全部潜力仍未得到开发。使用脂多糖 (LPS) 建立了 CEP 变性的体外和体内模型。我们设计了基因工程外泌体（CAP-Nrf2-Exos），其表面表达软骨细胞亲和肽（CAP）并携带抗氧化转录因子核因子E2相关因子2（Nrf2）。通过体外内化测定和体内成像测定评估 CAP-Nrf2-Exos 和 CEP 之间的亲和力。进行 qRT-PCR、Western blotting 和免疫荧光测定来检查 Nrf2 的表达水平以及 Nrf2 和 Drp1 的亚细胞定位。通过 JC-1 探针和 MitoSOX Red 测量线粒体功能。通过 MitoTracker 染色和透射电子显微镜 (TEM) 观察线粒体形态。终板下注射工程化外泌体后，通过放射学和组织学验证了 CEP 变性和 IVDD 的程度。我们发现，表面修饰提高了货物包装后外泌体的货物递送效率。 CAP-Nrf2-Exos 促进 Nrf2 的软骨细胞靶向递送，并激活 CEP 细胞中的内源性抗氧化防御系统。工程外泌体抑制 Drp1 S616 磷酸化和线粒体易位，从而防止线粒体断裂和功能障碍。 CAP-Nrf2-Exo 处理可减轻 LPS 诱导的 CEP 细胞凋亡。在 CEP 变性大鼠模型中，工程外泌体成功减轻了 CEP 变性和 IVDD，并表现出比天然外泌体更好的修复能力。总的来说，我们的研究结果表明，外泌体介导的 Nrf2 软骨细胞靶向递送是治疗 CEP 变性的有效策略。 © 2024。作者。

Cartilaginous endplate (CEP) degeneration, which is an important contributor to intervertebral disc degeneration (IVDD), is characterized by chondrocyte death. Accumulating evidence has revealed that dynamin-related protein 1 (Drp1)-mediated mitochondrial fission and dysfunction lead to apoptosis during CEP degeneration and IVDD. Exosomes are promising agents for the treatment of many diseases, including osteoporosis, osteosarcoma, osteoarthritis and IVDD. Despite their major success in drug delivery, the full potential of exosomes remains untapped.In vitro and in vivo models of CEP degeneration were established by using lipopolysaccharide (LPS). We designed genetically engineered exosomes (CAP-Nrf2-Exos) expressing chondrocyte-affinity peptide (CAP) on the surface and carrying the antioxidant transcription factor nuclear factor E2-related factor 2 (Nrf2). The affinity between CAP-Nrf2-Exos and CEP was evaluated by in vitro internalization assays and in vivo imaging assays. qRT‒PCR, Western blotting and immunofluorescence assays were performed to examine the expression level of Nrf2 and the subcellular localization of Nrf2 and Drp1. Mitochondrial function was measured by the JC-1 probe and MitoSOX Red. Mitochondrial morphology was visualized by MitoTracker staining and transmission electron microscopy (TEM). After subendplate injection of the engineered exosomes, the degree of CEP degeneration and IVDD was validated radiologically and histologically.We found that the cargo delivery efficiency of exosomes after cargo packaging was increased by surface modification. CAP-Nrf2-Exos facilitated chondrocyte-targeted delivery of Nrf2 and activated the endogenous antioxidant defence system in CEP cells. The engineered exosomes inhibited Drp1 S616 phosphorylation and mitochondrial translocation, thereby preventing mitochondrial fragmentation and dysfunction. LPS-induced CEP cell apoptosis was alleviated by CAP-Nrf2-Exo treatment. In a rat model of CEP degeneration, the engineered exosomes successfully attenuated CEP degeneration and IVDD and exhibited better repair capacity than natural exosomes.Collectively, our findings showed that exosome-mediated chondrocyte-targeted delivery of Nrf2 was an effective strategy for treating CEP degeneration.© 2024. The Author(s).