Concentrated exosomes from menstrual blood-derived stromal cells improves ovarian activity in a rat model of premature ovarian insufficiency.

BACKGROUND Premature ovarian insufficiency (POI) is one of the major causes of infertility. We previously demonstrated that transplantation of menstrual blood-derived stromal cells (MenSCs) effectively improved ovarian function in a murine model of POI. Recent studies indicated that mesenchymal stem cell-derived exosomes were important components in tissue repair. In this study, we investigated the therapeutic effects of MenSCs-derived exosomes (MenSCs-Exos) in a rat model of POI and its mechanism in restoring ovulation. METHODS Ovaries of 4.5-day-old Sprague Dawley rats (SD rats) were cultured in vitro to evaluate the effects of MenSCs-Exos exposure on early follicle development. Furthermore, POI in rats was induced by intraperitoneal administration of 4-vinylcyclohexene diepoxide (VCD). Forty-eight POI rats were randomly assigned to four groups, each receiving a different treatment: PBS, MenSCs, MenSCs-Exos, and Exo-free culture supernatant of MenSCs. Estrous cyclicity, ovarian morphology, follicle dynamics, serum hormones, pregnancy outcomes, and molecular changes were investigated. RESULTS Exposure to MenSCs-Exos promoted the proliferation of granulosa cells in primordial and primary follicles in vitro and increased the expression of early follicle markers Deleted In Azoospermia Like (DAZL) and Forkhead Box L2 (FOXL2) while inhibiting follicle apoptosis. In vivo, MenSCs-Exos transplantation effectively promoted follicle development in the rat model of POI and restored the estrous cyclicity and serum sex hormone levels, followed by improving the live birth outcome. In addition, transplantation of MenSCs-Exos regulated the composition of the ovarian extracellular matrix and accelerated the recruitment of dormant follicles in the ovarian cortex and increased proliferation of granulosa cells in these follicles. CONCLUSION MenSCs-Exos markedly promoted follicle development in vitro and in vivo and restored fertility in POI rats, suggesting a restorative effect on ovarian functions. The therapeutic effect of MenSCs-Exos transplantation was sustainable, consistent with that of MenSCs transplantation. Our results suggested that MenSCs-Exos transplantation may be a promising cell-free bioresource in the treatment of POI.