Effect of Interleukin-7 on In Vitro Maturation of Porcine Cumulus-Oocyte Complexes and Subsequent Developmental Potential after Parthenogenetic Activation

Abstract

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.