Abstract
Simple SummaryOocyte-secreted factors play an essential role in oogenesis and fertility through bidirectional crosstalk between oocytes and somatic cells. Interleukin-7, known as an oocyte-secreted factor, has recently been shown to improve oocyte developmental competence through interaction with cumulus cells around the oocytes. This study aimed to investigate the effects of interleukin-7 on porcine cumulus-oocyte complexes during in vitro maturation. Our results showed that supplementation with interleukin-7 during in vitro maturation exerted beneficial effects on porcine oocyte meiotic maturation by upregulating antioxidant-related genes and enhanced the subsequent developmental potential of porcine embryos after parthenogenetic activation.Interleukin-7 (IL-7) is a cytokine essential for cell development, proliferation and survival. However, its role in oocyte maturation is largely unknown. To investigate the effects of IL-7 on the in vitro maturation (IVM) of porcine oocytes, we analyzed nuclear maturation, intracellular glutathione (GSH) and reactive oxygen species (ROS) levels, and subsequent embryonic developmental competence after parthenogenetic activation (PA) under several concentrations of IL-7. After IVM, IL-7 treated groups showed significantly higher nuclear maturation and significantly decreased intracellular ROS levels compared with the control group. All IL-7 treatment groups exhibited significantly increased intracellular GSH levels compared with the control group. All oocytes matured with IL-7 treatment during IVM exhibited significantly higher cleavage and blastocyst formation rates after PA than the non-treatment group. Furthermore, significantly higher mRNA expression levels of developmental-related genes (PCNA, Filia, and NPM2) and antioxidant-related genes (GSR and PRDX1) were observed in the IL-7-supplemented oocytes than in the control group. IL-7-supplemented cumulus cells showed significantly higher mRNA expression of the anti-apoptotic gene BCL2L1 and mitochondria-related genes (TFAM and NOX4), and lower transcript levels of the apoptosis related-gene, Caspase3, than the control group. Collectively, the present study suggests that IL-7 supplementation during porcine IVM improves oocyte maturation and the developmental potential of porcine embryos after PA.
Highlights
Porcine embryos derived from in vitro maturation (IVM) are useful for research regarding reproduction [1,2]
To improve the efficiency of porcine IVM, addition of various growth factors and other molecules to the IVM medium has been suggested [8,9,10]. These efforts have led to significant advances in the porcine IVM system, the in vitro matured oocytes exhibit lower developmental competence compared with matured oocytes in vivo, as the in vitro environment is not as optimum as in folliculogenesis [11]
We investigated whether IL-7 is effective in both porcine IVM and the subsequent pre-implantation embryonic development following parthenogenetic activation (PA)
Summary
Porcine embryos derived from in vitro maturation (IVM) are useful for research regarding reproduction [1,2]. As pigs have an organ structure that is physiologically similar to that of humans, many studies use porcine embryos in the field of biomedical research [3,4,5]. To improve the efficiency of porcine IVM, addition of various growth factors and other molecules to the IVM medium has been suggested [8,9,10]. These efforts have led to significant advances in the porcine IVM system, the in vitro matured oocytes exhibit lower developmental competence compared with matured oocytes in vivo, as the in vitro environment is not as optimum as in folliculogenesis [11]
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