Graduate Student Chungbuk National University Chungbuk National University/Laboratory of Veterinary Embryology and Biotechnology, Ch'ungch'ong-bukto, Republic of Korea
Abstract: Pigs are valuable biomedical models due to their physiological similarities to humans, making them crucial for studying complex diseases and advancing medical research. However, the low efficiency of porcine transgenic model production highlights the need to improve oocyte quality during in vitro maturation (IVM). Fibroblast growth factor 8 (FGF8), a key cytokine in embryogenesis, is known to influence murine oocyte maturation, but its role in porcine oocytes remains unclear. This study investigated the effects of FGF8 supplementation during IVM on nuclear maturation, intracellular glutathione (GSH) levels, reactive oxygen species (ROS) levels, cumulus expansion, and parthenogenetic activation (PA). Immunohistochemistry localized FGF8 and its receptor FGFR4 in porcine follicles, showing FGF8 in cumulus cells and oocytes across all follicular stages, while FGFR4 was detected only in oocytes. Porcine oocytes were matured in vitro with FGF8 concentrations of 0, 1, 10, and 100 ng/mL. After 42 hours, the 100 ng/mL FGF8 group showed significantly (p < 0.05) higher nuclear maturation rates, elevated GSH levels indicating improved cytoplasmic maturation, and reduced ROS levels compared to controls. This group also exhibited significantly (p < 0.05) enhanced cumulus expansion and higher blastocyst rates in PA. These findings suggest that FGF8 influences both oocytes and cumulus cells, enhancing their maturation and promoting embryonic development. Additionally, co-culture of FGF8 with FGFR4 inhibitor BLU9931 eliminated the beneficial effects observed with FGF8 treatment, confirming that these effects are mediated through the FGFR4 pathway. In further research, we will focus on elucidating the mechanisms by which FGF8 enhances porcine oocyte maturation and embryonic development through comprehensive analysis of signaling pathways and mRNA expression profiles. By providing novel insights into oocyte-cumulus cell interactions, these findings have the potential to optimize IVM protocols, thereby improving the efficiency of porcine IVP and reinforcing their utility as biomedical models.
Funding Source: This work was supported by grants from the “NRF (2021R1C1C2013954)”, “Technology Innovation Program funded by the MOTIE, Korea (20023068)”, and “IPET funded by MAFRA (RS-2024-00398561, RS-2024-00399475)", Republic of Korea
