MiR-23a-5p was essential in promoting oligodendrogenesis afforded by M2-EVs in vitro and in vivo. (A-B) RT-PCR analysis of miR-23a-5p expression in cn-BV2 and kd-BV2 (A), cn-EVs and kd-EVs (B) (n = 3). (C-D) CCK-8 analysis of OPC viability that treated with 7.5, 15, 30 µg/mL of cn-EVs and kd-EVs under normal condition (C) and after OGD (D) (n = 4). (E) Representative images and quantification of PDGFR-α(green) and MBP (red) cells in OPCs treated with cn-EVs and kd-EVs after differentiation for 5 days (n = 3). Scale bar = 100 µm. (F) Western blot analysis and quantification of MBP expression in OPCs after differentiation for 5 days (n = 3). (G-J) Quantification and representative immunofluorescent images of NG2/Ki67 (G, I) and APC/Ki67 (H, J) staining in the striatum after 28 days of tMCAO in the PBS, cn-EVs and kd-EVs group (n = 3). Scale bar = 50 µm. Arrows indicate the NG2+Ki67+ or APC+Ki67+ cells. Data are mean ± SD, */#/$, p < 0.05; **/$$, p < 0.01, ***/###, p < 0.005; *, cn-EVs group vs. PBS group; #, kd-EVs group vs. PBS group; $, cn-EVs group vs. kd-EVs group.