Department of Joint Surgery, First Affiliated Hospital of Sun Yat-sen University, #58 Zhongshan 2nd Road, Guangzhou, 510080, China.
Stem Cell Res Ther. 2018 Sep 26;9(1):247. doi: 10.1186/s13287-018-1004-0.
WNT5A is known to be involved in the pathogenesis of osteoarthritis. This study investigated the molecular mechanism of exosomal miR-92a-3p and WNT5A in chondrogenesis and cartilage degeneration.
Exosomal miR-92a-3p expression was assessed in vitro in a human mesenchymal stem cell (MSC) model of chondrogenesis and in normal and OA primary human chondrocytes (PHCs). MSCs and PHCs were treated with exosomes derived from MSC-miR-92a-3p (MSC-miR-92a-3p-Exos) or its antisense inhibitor (MSC-anti-miR-92a-3p-Exos), respectively. Small interfering RNAs (siRNAs) and luciferase reporter assay were used to reveal the molecular role of exosomal miR-92a-3p and WNT5A in chondrogenesis. The protective effect of exosomes in vivo was measured using Safranin-O and Fast Green staining and immunohistochemical staining.
Exosomal miR-92a-3p expression was elevated in the MSC chondrogenic exosome, while it was significantly reduced in the OA chondrocyte-secreted exosome compared with normal cartilage. Treatment with MSC-miR-92a-3p-Exos promoted cartilage proliferation and matrix genes expression in MSCs and PHCs, respectively. In contrast, treatment with MSC-anti-miR-92a-3p-Exos repressed chondrogenic differentiation and reduced cartilage matrix synthesis by enhancing the expression of WNT5A. Luciferase reporter assay demonstrated that miR-92a-3p suppressed the activity of a reporter construct containing the 3'-UTR and inhibited WNT5A expression in both MSCs and PHCs. MSC-miR-92a-3p-Exos inhibit cartilage degradation in the OA mice model.
Our results suggest that exosomal miR-92a-3p regulates cartilage development and homeostasis by directly targeting WNT5A. This indicates that exosomal miR-92a-3p may act as a Wnt inhibitor and exhibits potential as a disease-modifying osteoarthritis drug.
WNT5A 已知参与骨关节炎的发病机制。本研究探讨了外泌体 miR-92a-3p 和 WNT5A 在软骨形成和软骨退变中的分子机制。
在人骨髓间充质干细胞（MSC）软骨形成模型以及正常和 OA 原代人软骨细胞（PHC）中评估外泌体 miR-92a-3p 的表达。分别用 MSC 衍生的 miR-92a-3p 外泌体（MSC-miR-92a-3p-Exos）或其反义抑制剂（MSC-anti-miR-92a-3p-Exos）处理 MSC 和 PHC。采用小干扰 RNA（siRNA）和荧光素酶报告基因检测揭示外泌体 miR-92a-3p 和 WNT5A 在软骨形成中的分子作用。通过番红 O 和 Fast Green 染色和免疫组织化学染色测量外泌体的体内保护作用。
MSC 软骨形成外泌体中 exosomal miR-92a-3p 的表达升高，而与正常软骨相比，OA 软骨细胞分泌的外泌体中 exosomal miR-92a-3p 的表达显著降低。MSC-miR-92a-3p-Exos 处理分别促进 MSC 和 PHC 中的软骨增殖和基质基因表达。相反，用 MSC-anti-miR-92a-3p-Exos 处理则通过增强 WNT5A 的表达来抑制软骨分化并减少软骨基质合成。荧光素酶报告基因检测表明，miR-92a-3p 抑制包含 3'-UTR 的报告构建体的活性，并在 MSC 和 PHC 中抑制 WNT5A 的表达。MSC-miR-92a-3p-Exos 抑制 OA 小鼠模型中的软骨降解。
我们的结果表明，外泌体 miR-92a-3p 通过直接靶向 WNT5A 调节软骨发育和稳态。这表明外泌体 miR-92a-3p 可能作为 Wnt 抑制剂发挥作用，并具有作为治疗骨关节炎的疾病修饰药物的潜力。
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