miR-381-abundant small extracellular vesicles derived from kartogenin-preconditioned mesenchymal stem cells promote chondrogenesis of MSCs by targeting TAOK1.

Small extracellular vesicles (sEVs) derived from mesenchymal stem cells have been shown to possess potent regenerative potential. In this study, we evaluated the chondrogenic effect of sEVs derived from kartogenin-preconditioned human umbilical cord mesenchymal stem cells (hUCMSCs). sEVs were isolated from the supernatants of KGN-preconditioned hUCMSCs (KGN-sEV) by gradient ultra-centrifugation, and internalized by native hUCMSCs, thereby inducing the chondrogenic differentiation. The underlying mechanism of KGN-sEV-induced chondrogenesis was explored by high-throughput sequencing and verified by transfection with the corresponding mimic and inhibitor. Sequencing identified the unique enrichment of a set of miRNAs in KGN-sEV compared with sEVs derived from unpreconditioned cells (un-sEV). Overexpression/inhibition in vitro and in vivo demonstrated that this chondrogenesis-inducing potential was primarily attributed to miR-381-3p, one of the most abundant miRNAs in KGN-sEV. Dual-luciferase reporter assays showed that miR-381-3p promoted chondrogenesis through direct suppression of TAOK1 by targeting its 3' untranslated region, thereby suppressing the Hippo signaling pathway. Collectively, our results highlight the regenerative potential of KGN-sEV to induce chondrogenic differentiation of MSCs, which is mainly achieved by delivering sEV-miR-381-3p, which targets TAOK1.