Exogenous Melatonin in the Culture Medium Does Not Affect the Development of In Vivo-Derived Pig Embryos but Substantially Improves the Quality of In Vitro-Produced Embryos

Abstract

Cloned and transgenic pigs are relevant human disease models and serve as potential donors for regenerative medicine and xenotransplantation. These technologies demand oocytes and embryos of good quality. However, the current protocols for in vitro production (IVP) of pig embryos give reduced blastocyst efficiency and embryo quality compared to in vivo controls. This is likely due to culture conditions jeopardizing embryonic homeostasis including the effect of reactive oxygen species (ROS) influence. In this study, the antioxidant melatonin (1 nM) in the maturation medium, fertilization medium, or both media was ineffective in enhancing fertilization or embryonic development parameters of in vitro fertilized oocytes. Supplementation of melatonin in the fertilization medium also had no effect on sperm function. In contrast, the addition of melatonin to the embryo culture medium accelerated the timing of embryonic development and increased the percentages of cleaved embryos and presumed zygotes that developed to the blastocyst stage. Furthermore, it increased the number of inner mass cells and the inner mass cell/total cell number ratio per blastocyst while increasing intracellular glutathione and reducing ROS and DNA damage levels in embryos. Contrarily, the addition of melatonin to the embryo culture medium had no evident effect on in vivo-derived embryos, including the developmental capacity and the quality of in vivo-derived 4-cell embryos or the percentage of genome-edited in vivo-derived zygotes achieving the blastocyst stage. In conclusion, exogenous melatonin in the embryo culture medium enhances the development and quality of in vitro-derived embryos but not in in vivo-derived embryos. Exogenous melatonin is thus recommended during embryo culture of oocytes matured and fertilized in vitro for improving porcine IVP efficiency.

Effects of Melatonin, GM-CSF, IGF-1, and LIF in Culture Media on Embryonic Development: Potential Benefits of Individualization

“…Overall, current studies support the finding that melatonin may enhance preimplantation embryonic development [67,68,[70][71][72] and the success rate of implantation [68,72], as indicated by human clinical studies and animal research. Furthermore, some studies indicate that melatonin could result in a reduction in ROS during embryo development, and this may lead to a decrease in DNA damage [70,72,73].…”

“…The most recent study with in vivo-derived and in vitro-derived porcine embryo examined the effects of the sequential addition of melatonin to the IVM, IVF, and culture medium by development competence [70]. Melatonin accelerated embryo development (p < 0.05), showing a significant increase in the cleavage development rate (p < 0.001) while indicating no notable difference in the blastocyst rate.…”

Maslinic Acid Supplementation during the In Vitro Culture Period Ameliorates Early Embryonic Development of Porcine Embryos by Regulating Oxidative Stress

“…Despite substantial progress in the field of IVC optimization, in vitro -derived embryos have a lower ratio of early-stage development than in vivo -cultured embryos [ 5 ]. Long-term accumulation of ROS within embryos during the process of IVC has been established as a significant factor altering in vitro embryo quality [ 6 ]. Importantly, OS caused by an imbalance between antioxidants and ROS can negatively affect the efficiency of IVC [ 7 ].…”

Combination of CNP, MT and FLI during IVM Significantly Improved the Quality and Development Abilities of Bovine Oocytes and IVF-Derived Embryos

“…Our study also demonstrated that the use of a novel IVM system based on CNP pretreatment considerably enhanced the developmental competence of the bovine oocytes ( Table 2 ), which was due to CNP increased oocytes cGMP levels [ 32 ]. Evidence from numerous studies on humans [ 33 ], bovine [ 26 , 34 , 35 ], and pigs [ 36 , 37 ] has shown that MT supplementation was beneficial for the IVM of oocytes and their development; and, reducing ROS levels depicts why the combination treatment of CNP and MT significantly enhanced the developmental competence of the bovine oocytes. The oocytes treated with CNP, MT, and FLI showed the highest development potential because FLI promoted porcine oocyte IVM by activating MAPK1/3 [ 19 , 38 ].…”