Large extracellular vesicles in bovine follicular fluid inhibit the apoptosis of granulosa cell and stimulate the production of steroid hormones.

The cargo carried by extracellular vesicles (EVs) plays an important physiological role in their corresponding target organs or target tissue cells. Extracellular vesicles are classified into large extracellular vesicles (LEVs) and small extracellular vesicles (SEVs) according to their diameters. Since different subtypes contain different contents, their roles are also different. In this study, the morphology and size of LEVs were analyzed by transmission electron microscopy and nanoparticle size, and the marker proteins of LEVs (CD63, GP96, TSG101, ALB) were identified by western blot, and high-purity LEVs were obtained. Through the uptake of extracellular vesicles by purified ovarian granulosa cells and the determination of granulosa cell viability, cell apoptosis, and steroid hormone production, the result indicated that LEVs significantly enhanced cell viability (P < 0.05), reduced the rate of granulosa cell apoptosis (P < 0.05). Meanwhile, LEVs promoted the secretion of estradiol in granulosa cells (P < 0.05). This study provides a reference for the in-depth study of the function of follicular fluid extracellular vesicle subtypes and the research on the regulation of extracellular vesicles on follicle and oocyte development.