Exosomes from human adipose–derived mesenchymal stem cells attenuate localized scleroderma fibrosis by the let-7a-5p/TGF-βR1/Smad axis.

Inflammation and fibrosis of the skin are characteristics of localized scleroderma (LS). Emerging evidence has demonstrated that exosomes from human adipose tissue–derived mesenchymal stem cells (ADSC-Exo) could alleviate skin fibrosis. The impact and potential mechanism of ADSC-Exo on LS fibrosis was examined. ADSC-Exo was isolated and identified. The effects of ADSC-Exo on the abilities of proliferation and migration of LS-derived fibroblasts (LSFs) were assessed by CCK-8 and scratch assays, respectively. qRT-PCR, western blot, and immunofluorescence were conducted to detect LSFs stimulated with ADSC-Exo, ADSC-ExoAnti-let−7a−5p, let-7a-5p mimic/TGF-βR1 shRNA virus, and negative controls. The impact of ADSC-Exo on C57BL/6j LS mice was evaluated by photographic morphology, hematoxylin-eosin (H&E), Masson's trichrome, and immunohistochemical staining. The verified ADSC-Exo limited the proliferation and migration of LSFs and reduced the expression of COL1, COL3, α-SMA, TGF-βR1, and p-Smad2/ 3 in vitro and in vivo. TGF-βR1 knockdown and let-7a-5p mimic in LSFs reduced the expression of COL1, COL3, α-SMA, and p-Smad2/3. However, compared with the ADSC-ExoNC group, the dermal thickness was increased, collagen arrangement was disordered, and α-SMA and TGF-βR1 levels were increased after exposure to ADSC-ExoAnti-let−7a−5p. In this study, it might show that ADSC-Exo may successfully prevent LSF bioactivity, collagen deposition, and myofibroblast trans-differentiation. Additionally, we confirmed that let-7a-5p in ADSC-Exo could directly target TGF-R1 to control the Smad pathway and reduce fibrosis in LSFs. Our work offered a brand-new therapeutic approach and clarified the unique mechanism for the clinical management of LS. • Exosomes from human adipose–derived mesenchymal stem cells attenuate localized scleroderma fibrosis. • Let-7a-5p directly targeted TGF-βR1 to control LS fibrosis. • TGF-βR1 was overexpressed in the LS animal model, and TGF-βR1 silencing decreased the expression of collagen and α-SMA in LSFs. • Let-7a-5p in ADSC-Exo could directly target TGF-R1 to control the Smad pathway and reduce fibrosis in LSFs. [ABSTRACT FROM AUTHOR]