Systemic sclerosis (SSc) is a potentially lethal disease with no curative treatment. Mesenchymal stromal cells (MSCs) have proved efficacy in SSc but no data is available on MSC-derived extracellular vesicles (EVs) in this multi-organ fibrosis disease. Small size (ssEVs) and large size EVs (lsEVs) were isolated from murine MSCs or human adipose tissue-derived MSCs (ASCs). Control antagomiR (Ct) or antagomiR-29a-3p (A29a) were transfected in MSCs and ASCs before EV production. EVs were injected in the HOCl-induced SSc model at day 21 and euthanasized at day 42. We found that both ssEVs and lsEVs were effective to slow-down the course of the disease. All disease parameters improved in skin and lungs. Interestingly, down-regulating miR-29a-3p in MSCs totally abolished therapeutic efficacy. Besides, we demonstrated a similar efficacy of human ASC-EVs and importantly, EVs from A29a-transfected ASCs failed to improve skin fibrosis. We identified Dnmt3a, Pdgfrbb, Bcl2, Bcl-xl as target genes of miR-29a-3p whose regulation was associated with skin fibrosis improvement. Our study highlights the therapeutic role of miR-29a-3p in SSc and the importance of regulating methylation and apoptosis.

系统性硬化症 (SSc) 是一种潜在的致命疾病，没有治愈性治疗。间充质基质细胞 (MSCs) 已证明对 SSc 有效，但没有关于 MSC 衍生的细胞外囊泡 (EVs) 在这种多器官纤维化疾病中的数据。小尺寸 (ssEVs) 和大尺寸 EVs (lsEVs) 是从小鼠 MSCs 或人类脂肪组织衍生的 MSCs (ASCs) 中分离出来的。在 EV 生产之前，将对照 antagomiR (Ct) 或 antagomiR-29a-3p (A29a) 转染到 MSCs 和 ASCs 中。在第 21 天将 EV 注射到 HOCl 诱导的 SSc 模型中，并在第 42 天实施安乐死。我们发现 ssEV 和 lsEV 均能有效减缓疾病的进程。皮肤和肺部的所有疾病参数都有所改善。有趣的是，下调 MSCs 中的 miR-29a-3p 完全消除了治疗效果。除了，我们证明了人类 ASC-EV 的类似功效，重要的是，来自 A29a 转染的 ASC 的 EV 未能改善皮肤纤维化。我们将 Dnmt3a、Pdgfrbb、Bcl2、Bcl-xl 鉴定为 miR-29a-3p 的靶基因，其调节与皮肤纤维化改善有关。我们的研究强调了 miR-29a-3p 在 SSc 中的治疗作用以及调节甲基化和细胞凋亡的重要性。