Role of Autophagy in Ovarian Cryopreservation by Vitrification.

BACKGROUND: Ovarian cryopreservation by vitrification and transplantation are useful methods to recover female fertility after radiotherapy and chemotherapy. As type II programmed cell death, autophagy plays important roles in ovarian follicle development, ovarian follicle atresia and anti-stress injury. OBJECTIVE: The potential role of autophagy in ovarian vitrification was investigated. MATERIALS AND METHODS: Mouse ovaries were cryopreserved by vitrification, and autophagy was treated, after which the ovarian histology was checked, and ovarian follicles were counted. The apoptotic rate was detected by TUNEL, and apoptotic molecular marker cleaved caspase-3 was checked by immunofluorescence and western blot analysis. RESULTS: Our results suggested that autophagy was increased in the process of vitrification compared with the fresh ovaries (p<0.05). The number of primordial follicles was decreased through inhibiting or over-activating the autophagy by autophagy inhibitor or activator (p<0.05). However, the number of primary follicles, antral follicles and atretic follicles was not significantly different compared with vitrified/warmed groups. The apoptotic rate was significantly increased in the vitrified/warmed, autophagy-inhibiting and over-activating groups compared with the fresh group (p<0.05), and this result was further confirmed by western blot analysis. CONCLUSIONS: Taken together, autophagy was activated in the ovarian cryopreservation by vitrification and plays a role in a natural adaptive response to cold stress in ovarian cryopreservation by vitrification.