Human umbilical cord mesenchymal stem cell-derived exosomes suppress dermal fibroblasts-myofibroblats transition via inhibiting the TGF-β1/Smad 2/3 signaling pathway

Objective: Exosomes originated from mesenchymal stem cells (MSCs) benefit wound healing. This study investigated effects of exosomes originated from human umbilical cord MSCs (hUC-MSCs) on dermal fibroblasts-myofibroblasts transition via the TGF-beta 1/Smad2/3 signaling pathway. Methods: Firstly, hUC-MSCs were collected and identified. Alizarin red, oil red O staining and toluidine blue staining were used to determine the osteogenic, adipogenic and chondrogenic differentiation abilities of hUC-MSCs. Then exosomes from hUC-MSCs were extracted and identified. To figure out the roles of exosomes and TGF-beta 1 in dermal fibroblasts-myofibroblasts transition, dermal fibroblasts were treated with TGF-beta 1 or/and exosomes at different concentrations. RT-qPCR, Western blot analyses were employed to examine levels of Collagen I, Collagen III, alpha-smooth muscle actin (alpha-SMA), and Smad2/3 phosphorylation, and immunofluorescence was employed to test alpha-SMA content and the localization and nucleation of Smad2/3 protein in cells. Results: hUC-MSCs and exosomes were successfully cultured and extracted. Levels of Collagen I, Collagen III, alpha-SMA, and Smad2/3, and Smad2/3 phosphorylation in fibroblasts treated with exosomes decreased markedly. After treatment with exosomes and TGF-beta 1 together, levels of Collagen I, Collagen III, alpha-SMA, and Smad2/3, and Smad2/3 phosphorylation in fibroblasts decreased significantly as compared to TGF-beta 1-treated fibroblasts. Exosome treatment reduced the entry of Smad2/3 into fibroblasts. Conclusion: Our data suggested that hUC-MSCs-derived exosomes could inhibit dermal fibroblasts-myofibroblasts transition by inhibiting the TGF-beta 1/Smad2/3 signaling pathway.