MSC Promotes the Secretion of Exosomal miR-34a-5p and Improve Intestinal Barrier Function Through METTL3-Mediated Pre-miR-34A m6A Modification.

Intestinal ischemia/reperfusion (I/R) injury (IIRI) is associated with high prevalence and mortality rate. Recently, mesenchymal stem cell (MSC) therapy attracted more attentions. However, the function and regulatory mechanism of MSC-derived exosomal miRNAs during IIRI remain largely uninvestigated. The in vitro and in vivo IIRI models were established. MSC were characterized by immunofluorescent staining and flow cytometry. Purified exosomes were characterized by transmission electron microscopy (TEM), flow cytometry, and western blot. The expression of key molecules was detected by western blot and qRT-PCR. CCK-8, TUNEL, and transepithelial electrical resistance (TER) assays were employed to assess cell viability, apoptosis, and intestinal integrity, respectively. Pre-miR-34A m6 modification was evaluated by methylated RNA immunoprecipitation (MeRIP)-qPCR. RNA pull-down and RIP were used to validate the direct association between pre-miR-34A and IGF2BP3. MSC-derived exosomal miR-34a-5p alleviated OGD/R-induced injury. In addition, MSC ameliorated OGD/R-induced injury through METTL3 pathway. Mechanistic study revealed that miR-34a-5p was modulated by METTL3/IGF2BP3-mediated m6A modification in MSC. The in vitro and in vivo functional experiments revealed that MSC secreted exosomal miR-34a-5p and ameliorated IIRI through METTL3/IGF2BP3-mediated m6A modification of pre-miR-34A. MSC promoted the secretion of exosomal miR-34a-5p and improved intestinal barrier function through METTL3/IGF2BP3-mediated pre-miR-34A m6A modification.