Regulation of myofibroblast transformation in airway repair by adipose-derived stem cell exosomes

Benign airway stenosis (BAS) remains a clinical challenge due to excessive myofibroblast transformation and scar formation, with limited effective therapies. Adipose-derived stem cell exosomes (ADSC-Exos) show tissue repair potential, but their epigenetic mechanism in alleviating airway stenosis is unclear. This study explored ADSC-Exos' role in airway repair and the underlying N6-methyladenosine (m6A) regulation. ADSCs were isolated from New Zealand white rabbit subcutaneous adipose tissue, characterized via flow cytometry (surface markers) and multipotent differentiation assays; ADSC-Exos were extracted by ultracentrifugation and identified using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. In vivo, a rabbit airway injury model (nylon brush injury) received local ADSC-Exos injection; in vitro, TGF-beta1-induced fibroblasts simulated myofibroblast transformation (groups: NS, ADSC co-culture, ADSC-Exos). Molecular analyses included MeRIP-seq, RNA-seq, western blotting, qRT-PCR, ELISA.Key results: ADSC-Exos significantly upregulated m6A methyltransferase METTL3 in vivo/in vitro, enhancing m6A methylation of TLR2 mRNA and downregulating TLR2 protein. Reduced TLR2 inhibited the PI3K-AKT pathway, decreasing myofibroblast markers alpha-SMA and Collagen 1. METTL3 overexpression/silencing reversed ADSC-Exos' inhibitory effect on myofibroblast transformation, and ADSC-Exos significantly improved rabbit airway repair. Combined MeRIP-seq/RNA-seq confirmed TLR2 as a key m6A target in the PI3K-AKT pathway. This study first identifies an epigenetic axis: ADSC-Exos upregulate METTL3 to enhance TLR2 mRNA m6A methylation, downregulate TLR2, inhibit PI3K-AKT, suppress myofibroblast transformation, and promote airway repair providing new insights into BAS pathogenesis and a basis for ADSC-Exos-based therapies.