Antioxidant effects and compatibility of zinc oxide nanoparticles during in vitro maturation of bovine oocytes and subsequent embryo development.

Zinc oxide nanoparticles (ZnO-NPs) have garnered significant attention in biological applications due to their known antioxidant properties. However, their potential impact on assisted reproduction techniques remains largely unexplored, particularly in the context of oocyte quality maintenance within in vitro culture systems, where free radicals can exert detrimental effects. This study investigated the effects of incorporating ZnO-NPs to in vitro maturation (IVM) media on the developmental, cryosurvival, and metabolic profiles of bovine embryos. Three concentrations of ZnO-NPs (0, 1.0, and 1.5 µg/mL) were evaluated. We observed, for the first time, that the inclusion of ZnO-NPs at a concentration of 1.0 µg/mL led to a significant increase in the number of embryonic cells (p < 0.05) accompanied by a reduction in reactive oxygen species production (p < 0.05). Notably, ZnO-NPs did not alter embryonic development, cryosurvival rates, or mitochondrial viability. These findings suggested that ZnO-NPs has antioxidant properties and are compatible with bovine oocytes. Consequently, they may serve as promising supplements to the IVM media, potentially enhancing the efficiency of assisted reproduction techniques.

Epigenetic modifiers during in vitro maturation as a strategy to increase oocyte competence in bovine.

Oocyte in vitro maturation (IVM) is a key procedure for the in vitro production (IVP) of bovine embryos; however, the efficiency of this step is limited by the intrinsic developmental competence of oocytes. This study aimed to investigate possible epigenetic changes resulting from using of histone deacetylase (HDAC) inhibitors in the maturation of bovine oocytes and subsequent embryo development. Initially, we investigated the meiotic progression of bovine oocytes matured in vitro in the presence of trichostatin A (TSA). We then evaluated histone H3k9 acetylation levels in oocytes exposed to different TSA concentrations, and the relative expression of genes linked to oocyte competence. Finally, we studied pre-implantation embryonic development by analyzing the cleavage, blastocysts, and hatching rates. Acetylation levels of H3k9 increased (p < 0.05) when oocytes were exposed to 50 nM or 100 nM TSA during IVM, but there were no significant changes in the relative expression of the evaluated genes p34cdc2, cyclin B1, MAPK, GDF9, G6PDH, and HSP70. We found that 5 nM TSA promoted the attenuation of meiotic progression and positively affected pre-implantation embryo development in bovine species, allowing a 10% increase in the blastocyst rate. We concluded that TSA treatment during IVM was efficient in promoting changes in H3k9 acetylation levels from 50 nM and promoted attenuated meiotic progression in bovine oocytes at all concentrations evaluated, with a positive impact on pre-implantation development when used at low concentrations.

Efficient delivery of DNA into bovine preimplantation embryos by multiwall carbon nanotubes.

The pellucid zone (PZ) is a protective embryonic cells barrier against chemical, physical or biological substances. This put, usual transfection methods are not efficient for mammal oocytes and embryos as they are exclusively for somatic cells. Carbon nanotubes have emerged as a new method for gene delivery, and they can be an alternative for embryos transfection, however its ability to cross the PZ and mediated gene transfer is unknown. Our data confirm that multiwall carbon nanotubes (MWNTs) can cross the PZ and delivery of pDNA into in vitro-fertilized bovine embryos. The degeneration rate and the expression of genes associated to cell viability were not affected in embryos exposed to MWNTs. Those embryos, however, had lower cell number and higher apoptotic cell index, but this did not impair the embryonic development. This study shows the potential utility of the MWNT for the development of new method for delivery of DNA into bovine embryos.

Biocompatibility assessment of fibrous nanomaterials in mammalian embryos.

Currently there is a growing interest in the use of nanotechnology in reproductive medicine and reproductive biology. However, their toxic effects on mammalian embryos remain poorly understood. In this work, we evaluate the biocompatibility of two fibrous nanomaterials (NMs): cotton cellulose nanofibers (CNF) and carboxylated multiwalled carbon nanotubes (MWCNT-COOH), by performing an investigation of the embryonic development, gene expression (biomarkers focused on cell stress, apoptosis and totipotency) and in situ apoptosis in bovine embryos. Exposure to NMs did not interfere in preimplantation development or in the incidence of apoptosis in the bovine embryo, but they did affect the gene expression. The results presented are important for an understanding of the toxicity of cotton CNF and MWCNT-COOH on mammalian embryos. To our knowledge, we report the first evaluation of biocompatibility between these NMs on preimplantation embryos, which may open a new window for reproductive biomedical applications.