Effect of polystyrene nanoplastics on in vitro maturation of pig cumulus-encosed oocytes

In recent years, concern has been increasing over the impact of environmental nanoplastics (NPs) contamination on both human and animal health, particularly regarding potential effects on reproductive systems. Nevertheless, current knowledge about the hazards posed by nanoplastics to mammalian gametes remains limited. In this study we evaluated the impact of increasing concentrations of polystyrene nanoplastics (PS-NPs)(5, 50, 100 and 200 μg/mL) on female gamete, using an in vitro model of pig oocyte maturation (IVM). Nuclear maturation, cytoplasmic maturation and developmental competence of oocytes, intracellular oocyte levels of glutathione (GSH) and reactive oxygen species (ROS), as well as steroidogenic activity of cumulus cells (CCs) were evaluated. Exposure to PS-NPs during IVM did not affect CCs steroidogenesis, oocyte nuclear maturation and oocyte cytoplasmic maturation in term of both fertilization parameters after IVF and blastocyst rate after parthenogenic activation. Nevertheless, PS-NPs significantly increased oocyte ROS levels at all the concentrations tested and compromised oocyte developmental competence, as indicated by reduced blastomere number per blastocyst. Our results confirm that PS-NPs may interfere with oocyte maturation and highlights the need to assess NPs exposure as an emerging environmental factor with potential implications for both animal and human fertility.