The interfering effects of superovulation and vitrification upon some important epigenetic biomarkers in mouse blastocyst.

Appropriate epigenetic changes in preimplantation embryos are critical for embryonic development and successful pregnancy. The aim of this study was to evaluate the effects of some assisted reproductive techniques (ARTs) on a panel of epigenetic biomarkers by immunofluorescence staining at blastocyst stage. For this purpose, four treatment groups were designed: control (C), superovulation (S), superovulation+in vitro culture (SI), and superovulation+vitrification+in vitro culture (SVI). Results showed that vitrification decreased the developmental competence of embryos cultured in vitro (P<0.05). Semi-quantitative analysis revealed that vitrification decreased the fluorescence intensity of global DNA methylation in the inner cell mass (ICM), in SVI Group in comparison to C group (P<0.05). Superovulation, elevated the level of H3K9acetylation of trophectoderm (TE) in comparison to C and SI groups (P<0.05). Furthermore, ARTs manipulations influenced H3K9acetylation in the ICM (P<0.05). The fluorescence intensity of H4K12acetylation in TE for SVI group was higher than C and S (P<0.05). For H3K4tri-methylation, S group had higher fluorescence intensity in the ICM in comparison to SI and SVI (P<0.05). Finally, in vitro culture decreased Pou5f1 protein signal in comparison to in vivo-derived embryos at blastocyst stage (P<0.05). In conclusion, ART manipulations may have important influences on multiple epigenetic biomarkers.

Can Vero cell co-culture improve in-vitro maturation of bovine oocytes?

This study was carried out to evaluate the effect of Vero cell co-culture on developmental competence of immature oocytes. Bovine cumulus-oocyte complexes (COC) were matured in presence or absence of Vero cells. Matured oocytes were inseminated and cultured for up to 9 days. Cleavage percentages were recorded on day 2 after insemination and embryos were evaluated on a daily basis. Expanding/expanded and hatching/hatched blastocysts were used for cell number assay. Results indicated a significantly greater cleavage percentage in oocytes matured in presence of Vero cells than control (86% versus 76%, P < or = 0.05). The percentages of advanced embryos appear to be greater on a daily basis in COC matured in presence of Vero cells compared with control. However, these differences were not significant. Blastocysts derived from COC matured in the presence of Vero cells had a significantly higher (P < or = 0.05) number of inner cell mass, trophectoderm and total cell number in expanding/expanded (65.25, 224.5 and 289.7 respectively) and hatching/hatched (67.75, 289.75 and 357.5) embryos in comparison to the control (42, 203.5, 245.5 and 51.3, 265, 316.3 respectively). Results confirm that co-culture of bovine COC during in-vitro maturation, enhances their ability for cleavage and for producing blastocysts with higher quality.