Effect of prematuration and maturation with fibroblast growth factor 10 (FGF10) on in vitro development of bovine oocytes

In an attempt to improve in vitro embryo production, we investigated the effect of FGF10 and 0.1 mM of cilostamide, cAMP modulator, during in vitro prematuration (PIVM) and in vitro maturation (IVM) on the developmental capacity of bovine oocytes. Five treatments (T) were used as follows: T1) IVM (control): COCs were matured for 22 h; T2) PIVM/IVM: COCs were submitted to 22 h of PIVM and 22 h of IVM; T3) PIVM + FGF10/IVM: COCs were submitted to PIVM for 22 h in the presence of FGF10 and matured for 22 h; T4) PIVM/IVM + FGF10: COCs were submitted to PIVM for 22 h and matured for 22 h in the presence of FGF10; and T5) PIVM + FGF10/IVM + FGF10: COCs were submitted to 22 h of PIVM and 22 h of IVM, both in the presence of FGF10. COCs were evaluated for CC expansion and nucleus configuration at 0 h, 22 h of PIVM and 22 h after IVM. At those time points, CCs were used for expression analysis of PTGS2, TNFAIP6, PTX3, HAS2, CASP8, CASP3, SLC2A1, SLC2A3 and FGFR2 genes. Then, embryo production was evaluated on D2 for cleavage and at D6, D7 and D8 for embryo development. Embryo quality was measured by the speed of development and by expression of KRT8, PLAC8, CD9, PAG2, PAG2, HSPB1, MSH6 genes. The percentage of COC that remained at GV after 22 h PIVM was lower (P < 0.05) in the treated group than in the control group, regardless of the addition of FGF10. Nevertheless at 22 h of maturation, none of the treatments affected the final rate of MII oocytes. No expansion of CCs was observed during the PIVM period. After 22 h of maturation expansion was similar (P > 0.05) for all groups but they all had lower expansion (P < 0.05) than control group. Except for PTGS2 and SLC2A1 which were unchanged during PIVM, all other genes changed their expression during PIVM. When we evaluated the changes in gene expression during IVM on the different groups, we noted a change in the expression of four genes (PTGS2, CASP8, PTX3 and TNFAIP6). No differences (P > 0.05) in the cleavage and blastocyst rates at D6 were observed among treatment groups. However, the blastocyst rates at D7 were lower (P < 0.05) than the control groups in which FGF10 was present either during PIVM or during IVM. When the speed of embryo development was evaluated on D7, embryos from groups PIVM-IVM and PIVM - IVM + FGF10 developed faster than the other groups. However, at D8, the hatching rate was similar (P > 0.05) for all groups. Of all the analysed genes, only PLAC8 was shown to be overexpressed in PIVM/IVM + FGF10, and MSH6 was less expressed (P < 0.05) in PIVM + FGF10/IVM + FGF10 group when compared with the control. According to these findings, the PIVM of COCs in the presence of FGF10 affected the molecular profile and the expansion of CCs without affecting the nuclear maturation and embryo production rates. Although the presence of FGF10 changed the expression of genes related to embryo quality it did not show a great impact when added either or both during PIVM and IVM.