MSCs-derived EVs protect against chemotherapy-induced ovarian toxicity: role of PI3K/AKT/mTOR axis

Chemotherapy detrimentally impacts fertility via depletion of follicular reserves in the ovaries leading to ovarian failure (OF) and development of estrogen deficiency-related complications. The currently proposed options to preserve fertility such as Oocyte or ovarian cortex cryopreservation are faced with many technical obstacles that limit their effective implementation. Therefore, developing new modalities to protect ovarian function remains a pending target. Exosomes are nano-sized cell-derived extracellular vesicles (EVs) with documented efficacy in the field of regenerative medicine. The current study sought to determine the potential beneficial effects of mesenchymal stem cells (MSCs)-derived EVs in experimentally induced OF. Female albino rats were randomly allocated to four groups: control, OF group, OF + MSCs-EVs group, OF + Rapamycin (mTOR inhibitor) group, and OF + Quercetin (PI3K/AKT inhibitor) group. Follicular development was assessed via histopathological and immunohistochemical examination, and ovarian function was evaluated by hormonal assay. PI3K/Akt/mTOR signaling pathway as a key modulator of ovarian follicular activation was also assessed. MSCs-EVs administration to OF rats resulted in restored serum hormonal levels, preserved primordial follicles and oocytes, suppressed ovarian PI3K/AKT axis and downstream effectors (mTOR and FOXO3), modulated miRNA that target this axis, decreased expression of ovarian apoptotic markers (BAX, BCl2) and increased expression of proliferation marker Ki67. The present study validated the effectiveness of MSCs-EVs therapy in preventing ovarian insufficiency induced by chemotherapy. Concomitant MSCs-EVs treatment during chemotherapy could significantly preserve ovarian function and fertility by suppressing the PI3K/Akt axis, preventing follicular overactivation, maintaining normal ovarian cellular proliferation, and inhibiting granulosa cell apoptosis.