Developmental competence of bovine oocytes in maturation media supplemented with follicular fluid exosomes

Abstract

The present study evaluated the role offollicular fluid exosomes on the developmental competence of bovine oocytes. Ovaries from slaughtered crossbred cattle were collected, all visible surface follicles aspirated, and culture-grade oocytes were subjected to further study. Exosomes were isolated from bovine follicular fluid by differential ultracentrifugation. A total of 358 oocytes selected for the study were randomly divided into two groups. Group I constituted 111 oocytes, in which normal maturation was carried. Group II constituted 247 oocytes, in which in vitro maturation (IVM) medium was supplemented with follicular fluid exosomes at 1 μL/100 μL IVM medium. Maturation was assessed after 24h of culture in a CO2 incubator maintained at 38.5°C in 95 per cent humidified atmosphere of 5 per cent CO2. Following IVM of oocytes for 24 h, in vitro fertilisation (IVF)was carried out by co-incubating with capacitated spermatozoa for 18 h and embryo culture was carried out subsequently. In group II oocytes supplemented with exosomes, a significantly higher maturation rate (p ≤0.01) (95.80 ±1.67 vs76.10 ± 0.95), fertilisation rate (53.68 ± 3.02vs37.85 ± 7.01) and cleavage rate (p ≤0.01) (43.66 ± 2.13vs(32.47 ± 5.23) was noticed compared to oocytes in group I without any supplementation.The present study established that supplementation of follicular fluid exosomescould improve the developmental competence of bovine oocytes.