Exposure to nanoscale graphene oxide deteriorates the quality of porcine oocytes via induction of oxidative stress and the apoptosis.

Abstract

Purpose: Nano graphene oxide (nGO), as a type of engineered carbon nanomaterial, has witnessed significant growth in biomedical applications. Given the likelihood of accumulation of these materials in human tissues or organs, it becomes imperative to comprehensively assess the toxicological profile of nGO, particularly concerning female reproductive health.

Methods: Germinal vesicle (GV) porcine oocytes were cultured at 38.5 °C to the specific developmental stage for subsequent analysis. The nGO was diluted with the maturation medium to the final concentrations of 10, 50, 100 and 200 μg/ml, respectively. Immunostaining and fluorescence intensity quantification were applied to assess the effects of nGO exposure on the key processes during the oocyte meiotic maturation.

Results: We observed that exposure to nGO led to compromised meiotic competency in porcine oocytes during in vitro culture. Specifically, nGO exposure resulted in reduced acetylation levels of α-tubulin and misattachment of kinetochore-microtubules, thereby disrupting spindle/chromosome organization and impeding meiotic progression. Furthermore, nGO exposure perturbed actin dynamics, potentially hindering spindle migration and cortical polarization during oocyte meiosis. Additionally, mislocalization and premature exocytosis of ovastacin were observed following nGO exposure. Notably, nGO exposure induced mitochondrial dysfunction, DNA damage, and oxidative stress, ultimately triggering apoptosis and impeding the maturation of porcine oocytes and the development of post-fertilized embryos.

Conclusion: Our findings underscore the potential deleterious effects of nGO on mammalian oocyte quality, while also contributing valuable insights into the impact of environmental nanoparticle release on female germ cell development.