Background/objectives

Articular cartilage erosion probably plays a substantial role in osteoarthritis (OA) initiation and development. Studies demonstrated that umbilical cord–derived mesenchymal stem cells (UCMSCs) could delay chondrocytes apoptosis and ameliorate OA progression in patients, but the detailed mechanisms are largely uncharacterised. In this study, we aimed to study the effects of UCMSCs on monosodium iodoacetate (MIA)–induced rat OA model, and explore the cellular mechanism of this effect.

Methods

Intra-articular injection of 0.3 ​mg MIA in 50 ​μL saline was performed on the left knee of the 200 ​g weight male Sprague-Dawley rat to induce rat knee OA. A single dose of 2.5 ​× ​10⁵ undifferentiated UCMSCs one day after MIA or three-time intra-articular injection of 2.5 ​× ​10⁵ UCMSCs on Days 1, 7 ​and 14 were given, respectively. Four weeks after MIA, joints were harvested and processed for paraffin sections. Safranine-O staining, haematoxylin and eosin staining ​and immunohistochemistry of MMP-13, ADAMTS-5, Col-2, CD68 ​and CD4 were performed to observe cartilage erosion and synovium. For in vitro ​studies, migration ability of cartilage superficial layer cells (SFCs) by UCMSCs were accessed by transwell assay. Furthermore, catabolism change of MIA-induced SFCs by UCMSCs was performed by real-rime polymerase chain reaction of Col-X and BCL-2 genes. CCK-8 assay was performed to check proliferation ability of SFCs by UCMSCs-conditioned media.

Result

In this study, we locally injected human UCMSCs, which is highly proliferative and noninvasively collectible, into MIA-induced rat knee OA. An important finding is on obviously ameliorated cartilage erosion and decreased OA Mankin score by repeated UCMSCs injection after MIA injection compared with single injection, both of which attenuated OA progression compared with vehicle. Interestingly, we observed significantly increased number of SFCs on the articular cartilage surface, probably related to elevated proliferation, mobilisation and inhibited catabolism marker: Col-X and BCL-2 gene expression of cultured SFCs by UCMSCs-conditioned media treatment in vitro. In addition to the change of unique SFCs, catabolism markers of ADAMTS-5 and MMP-13 were substantially upregulated in the whole cartilage layer chondrocytes as well. Strikingly, MIA-induced inflammatory cells infiltration, on both CD4+ Th cells and CD68+ macrophages, and hyperplasia of the synovium, which was alleviated by repeated UCMSCs injection.

Conclusion

Our study demonstrated a critical role of repeated UCMSCs dosing on preserving SFCs function, cartilage structure and inhibiting synovitis during OA progression, and thus provided mechanistic proof of evidence for the use of UCMSCs on OA patients in the future.

The translational potential of this article

UCMSCs are a relatively “young” stem cell, and noninvasively collectible. In our study, we clearly demonstrated that it could effectively delay OA progression, possibly through reserving SFCs function and inhibiting synovitis. Therefore, it could be a new promising therapeutic cell source for OA after further clinical trials.

中文翻译：

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多个脐带来源的 MSCs 给药通过保留关节软骨表层细胞和抑制滑膜炎来减轻大鼠骨关节炎的进展。

背景/目标

关节软骨侵蚀可能在骨关节炎 (OA) 的发生和发展中起重要作用。研究表明，脐带来源的间充质干细胞 (UCMSCs) 可以延缓患者的软骨细胞凋亡并改善 OA 进展，但其详细机制在很大程度上尚未确定。在本研究中，我们旨在研究 UCMSCs 对碘乙酸单钠 (MIA) 诱导的大鼠 OA 模型的影响，并探讨这种影响的细胞机制。

方法

在 200 g 体重的雄性 Sprague-Dawley 大鼠的左膝关节内注射 50 μL 盐水中的 0.3 mg MIA，以诱导大鼠膝关节 OA。在MIA后1天单次给予2.5 × 10 ⁵未分化UCMSCs或在第1、7和14天分别给予3次2.5 × 10 ⁵ UCMSCs关节内注射。MIA 后 4 周，采集关节并加工用于石蜡切片。进行番红-O染色、苏木精和伊红染色以及MMP-13、ADAMTS-5、Col-2、CD68和CD4的免疫组化，观察软骨侵蚀和滑膜。对于体外 ​研究，通过 transwell 测定法获得了 UCMSCs 对软骨表层细胞 (SFCs) 的迁移能力。此外，通过 Col-X 和 BCL-2 基因的实时聚合酶链反应进行了 UCMSCs 对 MIA 诱导的 SFC 的分解代谢变化。进行 CCK-8 测定以检查 UCMSCs 条件培养基对 SFCs 的增殖能力。

结果

在这项研究中，我们将具有高度增殖性和非侵入性可收集性的人类 UCMSCs 局部注射到 MIA 诱导的大鼠膝关节 OA 中。一个重要的发现是，与单次注射相比，MIA 注射后重复 UCMSCs 注射明显改善了软骨侵蚀并降低了 OA Mankin 评分，与载体相比，这两者都减弱了 OA 进展。有趣的是，我们观察到关节软骨表面 SFC 的数量显着增加，这可能与增殖、动员和抑制分解代谢标志物升高有关：通过 UCMSCs 条件培养基体外处理培养的 SFC 的 Col-X 和 BCL-2 基因表达. 除了独特的 SFC 发生变化外，ADAMTS-5 和 MMP-13 的分解代谢标志物在整个软骨层软骨细胞中也显着上调。引人注目的是，MIA 诱导的 CD4+ Th 细胞和 CD68+ 巨噬细胞上的炎症细胞浸润，以及滑膜增生，这通过反复注射 UCMSCs 得到缓解。

结论

我们的研究证明了重复给药 UCMSCs 在 OA 进展过程中对保持 SFCs 功能、软骨结构和抑制滑膜炎的关键作用，从而为未来在 OA 患者中使用 UCMSCs 提供了机械证据。

本文的翻译潜力

UCMSCs 是一种相对“年轻”的干细胞，可以无创收集。在我们的研究中，我们清楚地证明了它可以有效地延缓 OA 的进展，可能是通过保留 SFC 的功能和抑制滑膜炎。因此，经过进一步的临床试验，它可能成为一种新的有前途的 OA 治疗细胞来源。