Exosomes from WTAP-depleted mesenchymal stem cells mitigate OGD/R-triggered cellular injury in SK-N-SH cells through m6A-dependent epigenetic silencing of RPL9

Abstract Background Exosomes from mesenchymal stem cells (MSCs Exo) have emerged as a promising cell-free therapeutic strategy for human diseases, including ischemic stroke (IS). Here, we investigated the mechanisms underlying the therapeutic potential of MSCs Exo. Methods SK-N-SH cells were exposed to oxygen-glucose deprivation/reoxygenation (OGD/R). Exosomes were isolated from untransfected (MSCs Exo) or shRNA-Wilms' tumor 1-associated protein (WTAP)-transfected MSCs (MSCs Exo-shWTAP) and used to incubate OGD/R-exposed SK-N-SH cells. The influence on cellular damage was evaluated by detecting cell viability, apoptosis, the expression of oxidative stress markers (ROS, MDA, and SOD), and the production of TNF-α, IL-6, and IL-1β cytokines. The regulation of WTAP in ribosomal protein L9 (RPL9) mRNA was assessed by mRNA stability analysis and methylated RNA immunoprecipitation (MeRIP) assay. Results RPL9 was upregulated in IS serum and OGD/R-exposed SK-N-SH cells. RPL9 depletion attenuated OGD/R-evoked apoptosis, oxidative stress, and pro-inflammatory cytokine production (TNF-α, IL-6, and IL-1β) in SK-N-SH cells. Mechanistically, WTAP regulated the mRNA stability and expression of RPL9 via an m6A-dependent way. MSCs Exo reduced RPL9 expression in OGD/R-exposed SK-N-SH cells, and MSCs Exo-shWTAP exerted a stronger reduction effect on RPL9 expression. MSCs Exo-shWTAP had stronger alleviative effects on OGD/R-triggered apoptosis, oxidative stress, and inflammation in SK-N-SH cells compared with MSCs Exo. Moreover, increased RPL9 expression abolished the effects of MSCs Exo-shWTAP. Conclusion Our findings indicate that WTAP depletion can enhance the alleviative effects of MSCs Exo on OGD/R-triggered cellular damage in SK-N-SH cells by downregulating RPL9. WTAP-depleted MSC-derived exosomes represent a promising therapeutic strategy for IS.