Exosomes derived from hypoxic mesenchymal stem cell ameliorate premature ovarian insufficiency by reducing mitochondrial oxidative stress.

Cyclophosphamide (CTX) exposure causes premature ovarian insufficiency (POI). The therapeutic potential of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs) is not fully understood, especially regarding whether hypoxic preconditioning enhances their efficacy in POI. In this study, exosomes were isolated and identified from hucMSCs (hucMSCs-Exos) under hypoxic (HExos) and normoxic (NExos) conditions. Cyclophosphamide (CTX) was used to develop the POI rat model, and NExos or HExos was injected into the tail vein to investigate its therapeutic effect on POI. In addition, CTX-treated KGN cell lines were used to investigate the effects of NExos and HExos on cell proliferation, apoptosis, oxidative stress and mitochondrial membrane potential.The results indicated that hucMSCs-Exos transplantation substantially improved body weight, ovarian weight coefficient, estrous cycles, ovarian morphology, ovulation count, and sex hormone levels in POI rats. Further, HExos showed a higher level of therapeutic efficiency than NExos. In vitro experiments demonstrated that NExos and HExos may be phagocytosed by KGN cell line, decrease cell apoptosis, and enhance cell growth. After NExos or HExos transplantation, the reactive oxygen species level was reduced, mitochondrial membrane potential enhanced, and the levels of mitochondrial oxidative stress-associated factors returned to their basal level. Notably, the improvement of oxidative stress by NExos or HExos was blocked by the SIRT3 selective inhibitor 3-TYP. In conclusion, hypoxia-induced hucMSCs-Exos protected the ovarian reserve against CXT-induced ovarian damage by rectifying mitochondrial malfunction via the SIRT3/PGC1-α pathway, establishing a solid basis for developing specific ovarian protection therapies.