Objective: The current study was designed to investigate the effects and underlying mechanisms of adipose tissue-derived stem cells (ADSCs) on hypertrophic scar (HS) fibrosis. Method: Real-time quantitative polymerase chain reaction (qRT-PCR) andWestern blot analysis were performed to detect the expression of collagen I (Col1), collagen III (Col3), and α-smooth muscle actin (α-SMA) after fibroblasts and cultured HS tissues were treated with ADSC medium. All data were analyzed by using SPSS17.0 software. Statistical analysis was performed by Student t tests.Results: The in vitro study showed that ADSC medium decreased the expression of Col1, Col3, and α-SMA. In addition, the protein level of p-p38 was downregulated by ADSC medium treatment in a concentration dependent manner. Conclusion: The current study demonstrated that ADSC could decrease collagen deposition and scar formation in in vitro experiments. The regulation of the p38/ MAPK signaling pathway might play an important role in the process. K E Y W O R D S ADSC, collagen, hypertrophic scars, myofibroblasts, p38/MAPK pathway, α-SMA J Cell Biochem. 2019;120:4057-4064.wileyonlinelibrary.com/journal/jcb

Hypertrophic scar (HS) is a dermal fibro-proliferative disorder result from abnormal wound healing after skin injury. MicroRNA-9-5p (miR-9-5p) has been reported to be upregulated and closely related to collagen proteins in human dermal fibroblasts. However, the correlation and possible mechanism between miR-9-5p and HS require further investigation. The expressions of miR-9-5p in HS tissues and HS fibroblasts were detected by quantitative real-time PCR (RT-qPCR). The expression level of peroxisome proliferator-activated receptor β (PPARβ) was measured by RT-qPCR assay. The protein levels of PPARβ, α-SMA, Vimentin, COL1A, cyclin D1, bcl-2, and bax were detected by western blot assay. The effect of miR-9-5p and PPARβ on HS fibroblasts proliferation and apoptosis were detected by cell counting kit-8 (CCK-8) and flow cytometry assays. The interaction between miR-9-5p and PPARβ was predicted by TargetScan, and then confirmed by dual-luciferase reporter assay. MiR-9-5p expression was downregulated in HS tissues and HS fibroblasts. MiR-9-5p inhibited the levels of extracellular matrix-associated genes (α-SMA, Vimentin, COL1A) in HS fibroblasts. MiR-9-5p repressed proliferation and induced apoptosis of HS fibroblasts. PPARβ is a target gene of miR-9-5p. The silencing of PPARβ expression hindered proliferation and expedited apoptosis of HS fibroblasts. MiR-9-5p suppressed proliferation and promoted apoptosis of HS fibroblasts by targeting PPARβ. In this paper, we firstly disclosed that miR-9-5p hampered extracellular matrix deposition and proliferation, and induced apoptosis by targeting PPARβ in HS fibroblasts. Our findings provided a new role of miR-9-5p/PPARβ in the occurrence and development of HS fibroblasts, promising a new target for HS.