Department of Orthopedics Trauma and Microsurgery, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China.
TaiKang Medical School (School of Basic Medical Sciences), Wuhan University, Wuhan, 430071, China.
J Nanobiotechnology. 2024 Oct 22;22(1):648. doi: 10.1186/s12951-024-02923-5.
By interacting with bone marrow mesenchymal stem cells (BMSCs) and regulating their function through exosomes, bone macrophages play crucial roles in various bone-related diseases. Research has highlighted a notable increase in the number of M1 macrophages in glucocorticoid-associated osteonecrosis of the femoral head (GA-ONFH). Nevertheless, the intricate crosstalk between M1 macrophages and BMSCs in the glucocorticoid-stimulated environment has not been fully elucidated, and the underlying regulatory mechanisms involved in the occurrence of GA-ONFH remain unclear.
We employed in vivo mouse models and clinical samples from GA-ONFH patients to investigate the interactions between M1 macrophages and BMSCs. Immunofluorescence staining was used to assess the colocalization of M1 macrophages and BMSCs. Flow cytometry and transcriptomic analysis were performed to evaluate the impact of exosomes derived from normal (n-M1) and glucocorticoid-stimulated M1 macrophages (GC-M1) on BMSC differentiation. Additionally, miR-1a-3p expression was altered in vitro and in vivo to assess its role in regulating adipogenic differentiation.
In vivo, the colocalization of M1 macrophages and BMSCs was observed, and an increase in M1 macrophage numbers and a decrease in bone repair capabilities were further confirmed in both GA-ONFH patients and mouse models. Both n-M1 and GC-M1 were identified as contributors to the inhibition of osteogenic differentiation in BMSCs to a certain extent via exosome secretion. More importantly, exosomes derived from GC-M1 macrophages exhibited a heightened capacity to regulate the adipogenic differentiation of BMSCs, which was mediated by miR-1a-3p. In vivo and in vitro, miR-1a-3p promoted the adipogenic differentiation of BMSCs by targeting Cebpz and played an important role in the onset and progression of GA-ONFH.
We demonstrated that exosomes derived from GC-M1 macrophages disrupt the balance between osteogenic and adipogenic differentiation in BMSCs, contributing to the pathogenesis of GA-ONFH. Inhibiting miR-1a-3p expression, both in vitro and in vivo, significantly mitigates the preferential adipogenic differentiation of BMSCs, thus slowing the progression of GA-ONFH. These findings provide new insights into the regulatory mechanisms underlying GA-ONFH and highlight potential therapeutic targets for intervention.
骨巨细胞通过与骨髓间充质干细胞（BMSCs）相互作用，并通过外泌体调节其功能，在各种与骨相关的疾病中发挥着关键作用。研究表明，糖皮质激素相关性股骨头坏死（GA-ONFH）患者的骨巨噬细胞中 M1 型巨噬细胞数量显著增加。然而，糖皮质激素刺激环境下 M1 巨噬细胞与 BMSCs 之间的复杂相互作用尚未完全阐明，GA-ONFH 发生的潜在调节机制仍不清楚。
我们采用体内小鼠模型和 GA-ONFH 患者的临床样本，研究 M1 巨噬细胞与 BMSCs 之间的相互作用。免疫荧光染色用于评估 M1 巨噬细胞和 BMSCs 的共定位。流式细胞术和转录组分析用于评估来自正常（n-M1）和糖皮质激素刺激的 M1 巨噬细胞（GC-M1）的外泌体对 BMSC 分化的影响。此外，体外和体内改变 miR-1a-3p 的表达水平，评估其在调节成脂分化中的作用。
在体内，观察到 M1 巨噬细胞和 BMSCs 的共定位，并且在 GA-ONFH 患者和小鼠模型中均进一步证实 M1 巨噬细胞数量增加和骨修复能力下降。n-M1 和 GC-M1 均通过外泌体分泌在一定程度上被鉴定为抑制 BMSCs 成骨分化的因素。更重要的是，GC-M1 巨噬细胞衍生的外泌体通过 miR-1a-3p 调节 BMSCs 的成脂分化能力增强。在体内和体外，miR-1a-3p 通过靶向 Cebpz 促进 BMSCs 的成脂分化，在 GA-ONFH 的发生和进展中发挥重要作用。
我们证明 GC-M1 巨噬细胞衍生的外泌体破坏了 BMSCs 成骨和成脂分化之间的平衡，导致 GA-ONFH 的发病机制。在体内和体外抑制 miR-1a-3p 的表达显著减轻 BMSCs 的成脂分化偏向性，从而减缓 GA-ONFH 的进展。这些发现为 GA-ONFH 的发病机制提供了新的见解，并强调了干预的潜在治疗靶点。
