FTO-overexpressing extracellular vesicles from BM-MSCs reverse cellular senescence and aging to ameliorate osteoarthritis by modulating METTL3/YTHDF2-mediated RNA m6A modifications

Extracellular vesicles secreted by bone marrow mesenchymal stem cells (BM-MSCs) exert therapeutic effects in osteoarthritis (OA). As an important N6-Methyladenosine (m6A) demethylase, it is reported that fat mass and obesity-associated protein (FTO) involves in regulating OA progression. Here, we generated MSCs-derived FTO-overexpressing EVs (FTO-EVs) to investigate whether FTO-EVs could be used for the potential treatment of OA. Our experiments verify that FTO-EVs suppressed cellular senescence, aging, apoptosis, and enhanced cell autophagy in LPS-treated chondrocytes in vitro and monosodium iodoacetate (MIA)-treated mice tissues in vivo. Also, ROS scavenger NAC reversed LPS-induced detrimental effects in chondrocytes. Mechanical experiments illustrated that FTO-EVs induced m6A-demethylation in autophagy-associated genes (Atg5 and Atg7) and pro-apoptosis gene (BNIP3), subsequently inducing the upregulation of Atg5/Atg7 and downregulation of BNIP3 in a YTHDF2-dependent manner, and the effects of FTO-EVs on the expressions of Atg5/Atg7 and BNIP3 were all reversed by upregulating m6A methyltransferase METTL3. Furthermore, FTO-EVs-induced suppressing effects on LPS-treated chondrocytes senescence and aging were abolished by Atg5/Atg7 knockdown and BNIP3 overexpression. In conclusion, this study evidenced that BM-MSCs-derived FTO-EVs suppressed cellular senescence and apoptosis, and triggered protective autophagy to suppress OA development through demethylating m6A modifications, and the engineering FTO-EVs could be potentially used to treat OA in clinic.