MSC-exos rescue G2/M arrest and reduce apoptosis via inhibiting p53 signaling through miR-125b-5p. (A) Schematic diagram depicted the predicted binding site of miR-125b-5p targeting the 3'-UTR of TP53. The underlined sequences represented the mutation seed sequence of 3'-UTR of TP53. (B) Luciferase reporter assay determined p53 as a bona fide target of miR-125b-5p (n = 3). NC, negative control; WT, wide type; MUT, mutant. (C) RT-PCR analysis of miR-125b-5p in miR-125b-5p inhibitor transfected MSCs (n = 4). (D) RT-PCR analysis of miR-125b-5p in exosomes isolated from miR-125b-5p inhibitor transfected MSC (miR-125b-5pIN-exos) (n = 4). RT-PCR (E) and Western blotting analysis (F) of p53 in HK-2 cells treated with miR-125b-5pIN-exos (n = 4). (G) Western blotting analysis of Cyclin B1, CDK1, Bcl-2 and Bax in HK-2 cells treated with miR-125b-5pIN-exos (n = 4). Flow cytometry analysis of cell cycle (H) and annexin V/PI staining (I) in miR-125b-5pIN-exos treated HK-2 cells (n = 3). Data are presented as mean ± SD, *p < 0.05, **p < 0.01, ***p < 0.001 vs. H/R group, #p < 0.05, ##p < 0.01, ###p < 0.001, unpaired Student's t-test (two-tailed) or one-way ANOVA.