Purpose: As a common complication of tendon injury, tendon adhesion is an unresolved problem in clinical work. The aim of this study was to investigate whether human umbilical cord mesenchymal stem cell-derived exosomes (HUMSC-Exos), one of the most promising new-generation cell-free therapeutic agents, can improve tendon adhesion and explore potential-related mechanisms.
Methods: The rat Achilles tendon injury adhesion model was constructed in vivo, and the localization of HUMSC-Exos was used to evaluate the tendon adhesion. Rat fibroblast cell lines were treated with transforming growth factor β 1 (TGF-β 1) and/or HUMSC-Exos in vitro, and cell proliferation, apoptosis and gene expression were measured. MicroRNA (miRNA) sequencing and quantitative PCR (qPCR) analysis confirmed differential miRNAs. A specific miRNA antagonist (antagomir-21a-5p) was used to transform HUMSC-Exos and obtain modified exosomes to verify its efficacy and related mechanism of action.
Results: In this study, we found HUMSC-Exos reduced rat fibroblast proliferation and inhibited the expression of fibrosis genes: collagen III (COL III) and α-smooth muscle actin (α-SMA) in vitro. In the rat tendon adhesion model, topical application of HUMSC-Exos contributed to relief of tendon adhesion. Specifically, the fibrosis and inflammation-related genes were simultaneously inhibited by HUMSC-Exos. Further, miRNA sequencing of HUMSCs and HUMSC-Exos showed that miR-21a-3p was expressed at low abundance in HUMSC-Exos. The antagonist targeting miR-21a-3p was recruited for treatment of HUMSCs, and harvested HUMSC-Exos, which expressed low levels of miR-21a-3p, and expanded the inhibition of tendon adhesion in subsequent in vitro experiments.
Conclusion: Our results indicate that HUMSC-Exos may manipulate p65 activity by delivering low-abundance miR-21a-3p, ultimately inhibiting tendon adhesion. The findings may be promising for dealing with tendon adhesion.

Keywords: HUMSC, exosome, tendon adhesion, TGF-β 1, p65, miR-21a-3p, NF-κB




中文翻译：

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MicroRNA-21-3p 工程脐带干细胞衍生的外泌体抑制肌腱粘附。

目的：作为肌腱损伤的常见并发症，肌腱粘连是临床工作中尚未解决的问题。本研究旨在探讨人类脐带间充质干细胞来源的外泌体（HUMSC-Exos）是最有前途的新一代无细胞治疗剂之一，是否可以改善肌腱粘附并探索潜在的相关机制。
方法：体内构建大鼠跟腱损伤粘连模型，利用HUMSC-Exos定位评价跟腱粘连情况。在体外用转化生长因子β1（TGF-β1）和/或HUMSC-Exos处理大鼠成纤维细胞系，并测量细胞增殖、凋亡和基因表达。MicroRNA (miRNA) 测序和定量 PCR (qPCR) 分析证实了差异 miRNA。使用特异性 miRNA 拮抗剂（antagomir-21a-5p）转化 HUMSC-Exos 并获得修饰的外泌体，以验证其功效和相关作用机制。
结果：在这项研究中，我们发现 HUMSC-Exos 在体外降低了大鼠成纤维细胞的增殖并抑制了纤维化基因的表达：胶原蛋白 III (COL III) 和 α-平滑肌肌动蛋白 (α-SMA)。在大鼠肌腱粘连模型中，局部应用 HUMSC-Exos 有助于缓解肌腱粘连。具体而言，HUMSC-Exos 同时抑制了纤维化和炎症相关基因。此外，HUMSCs 和 HUMSC-Exos 的 miRNA 测序显示 miR-21a-3p 在 HUMSC-Exos 中以低丰度表达。招募靶向 miR-21a-3p 的拮抗剂用于治疗 HUMSCs，并收获了表达低水平 miR-21a-3p 的 HUMSC-Exos，并在随后的体外实验中扩大了对肌腱粘连的抑制作用。
结论：我们的结果表明，HUMSC-Exos 可以通过提供低丰度的 miR-21a-3p 来操纵 p65 活性，最终抑制肌腱粘附。这些发现可能对处理肌腱粘连很有希望。

关键词： HUMSC，外泌体，肌腱粘附，TGF-β1，p65，miR-21a-3p，NF-κB