Regulation of hypoxia-inducible factor 1a by optimal oxygen concentration enhances oocyte maturation and early embryonic development in buffalo

Despite significant progress in vitro maturation (IVM) and in vitro culture (IVC) of oocytes and embryos, their developmental competence remains low. To address this issue, we used buffalo oocytes as a model system to investigate the effects and mechanisms of oxygen concentration on IVM and IVC. Our findings demonstrated that culturing buffalo oocytes with 5% oxygen significantly enhanced the efficiency of IVM and developmental competence of early embryos. Immunofluorescence results suggested that HIF1a played a critical role in these progresses. RT-qPCR results showed that maintaining a stable expression of HIF1a in cumulus cells with 5% oxygen concentration enhanced glycolysis, expansion, and proliferation abilities, up-regulated the expression of development-related genes, and suppressed apoptosis level. Consequently, it improved the maturation efficiency and quality of oocytes, leading to improve devel-opmental capacity of buffalo early embryos. Similar outcomes were also observed when embryos were cultured with 5% oxygen. Collectively, our study provided insights into the role of oxygen regulation during oocytes maturation and early embryo development, and could potentially improve the efficiency of human assisted-reproduction technology.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

Culturing buffalo oocytes and embryos with 5% oxygen concentration improves their developmental competence, possibly through the regulation of HIF1a expression and glycolysis. This study provides insights into the role of oxygen regulation in oocytes maturation and early embryo development.