Adipose-Derived Mesenchymal Stem Cell Exosome miR-146a-5p Attenuates TGF-β2-Induced Transformation of Human Tenon's Capsule Fibroblasts by Targeting SMAD4.

PURPOSE: Conjunctival fibrosis is the major impediment to the success of glaucoma filtration surgery. Exosomes secreted by human adipose-derived mesenchymal stem cells (hADSCs) could alleviate a variety of tissue fibrosis. However, the molecular mechanism of hADSCs-derived exosomes (hADSC-exos) in postoperative glaucoma follicle scarring is still unclear. METHODS: The hADSC-exos were identified by a transmission electron microscope and nanoparticle tracking analysis. The hADSC-exos were traced in vitro by PKH67 staining, and uptake of exosomes by human Tenon's capsule fibroblast (HTF) cells was detected by the confocal method. After co-culturing hADSC-exos and transforming growth factor beta-2 (TGF-β2), HTF proliferation and migration were detected using Cell Counting Kit-8 and wound healing assay. Protein levels were examined using Western blot. The binding between miR-146a-5p and SMAD4 was predicted and verified using dual-luciferase reporter and RNA immunoprecipitation assay. Gain/loss-of-function studies using microRNA (miRNA)-modified exosomes and direct mimic transfection were performed. Anti-fibrotic efficacy was examined by a trabeculectomy model using New Zealand white rabbits in vivo. RESULTS: The hADSC-exos could be internalized by HTFs. The miRNA-146a-5p is the most significantly upregulated in HTFs co-stimulated by TGF-β2 and hADSC-exos. After the screening, miR-146a-5p may be a potential target in HTFs treated with TGF-β2 combined with hADSCs-exos. Furthermore, hADSC exosomal miR-146a-5p inhibited TGF-β2-triggered HTF proliferation, migration, and fibrosis by targeting SMAD4. The miR-146a-5p inhibitor-loaded exosomes exacerbated fibrosis. Meanwhile, hADSC exosomal miR-146a-5p could attenuate fibrosis and collagen deposition in the tissue surrounding the glaucoma postoperative filter vesicles in vivo. CONCLUSIONS: The hADSC exosomal miR-146a-5p attenuated TGF-β2-stimulated HTF fibrotic response by targeting SMAD4.