MiR-21-5p delivered by exosomes of placental mesenchymal stem cells targets the PTEN/AKT/mTOR axis to inhibit ovarian granulosa cell apoptosis

Abstract

Abstract Background: This study aims to determine the therapeutic effect of placental mesenchymal stem cell exosomes ((PMSC-Exos) on premature ovarian insufficiency (POI) and explore the mechanism of inhibiting ovarian granulosa cells (OGCs) apoptosis. Methods: Exos were extracted from PMSCs and identified by transmission electron microscopy(TEM), nanoparticle tracking analysis(NTA), and Western blot (WB). OGC induced by cisplatin was used to establish POI models in vitro, and the therapeutic effect of PMSC-Exos on POI was evaluated by flow cytometry, WB, cell counting kit-8 (CCK-8), and wound-healing assay. The results of miRNA microarray assay of PMSC-Exos showed that miR-21-5p was the most enriched miRNA. The target gene of miR-21-5p identified by the database and references was PTEN. The regulatory effect of miR-21-5p on PTEN was verified by dual luciferase reporter assay, WB, and qRT-PCR. Then, rescue experiments were designed to fully confirm the regulatory mechanism of miR-21-5p on the PTEN/AKT/mTOR axis. Finally, WB, flow cytometry, CCK-8, and wound-healing assay were used to verify that miR-21-5p carried by PMSC-Exos protected OGCs by targeting the PTEN/AKT/mTOR axis. Results: The co-culture of PMSC-Exos with OGCs inhibited cisplatin-induced apoptosis and promoted cell proliferation and migration. These therapeutic effects significantly decreased after miR-21-5p knockdown. Dual luciferase reporter assay, WB, and qRT-PCR verified that miR-21-5p could target PTEN to inhibit its expression. Finally, multiple experimental groups were designed to verify that miR-21-5p delivered by PMSC-Exos to granulosa cells could bind to the 3ʹ untranslated region (UTR) of PTEN, thus regulating the AKT/mTOR pathway and playing a positive role in inhibiting apoptosis of OGCs and promoting cell proliferation and migration. Conclusion: MiR-21-5p carried by PMSC-Exos inhibits OGCs apoptosis by targeting the PTEN/AKT/mTOR axis. This finding provides a new idea for the precision treatment of POI and the cell-free treatment of Exos.