Effects of fructose supplementation in chemically defined protein-free medium on development of bovine in vitro fertilized embryos

Effects of Leonurine on oocyte maturation and parthenogenetic embryo development in sheep

Leonurine (LEO), an alkaloid isolated from Leonurus spp., has anti-oxidant, anti-inflammatory and anti-apoptotic effects and can prevent damage caused by reactive oxygen species (ROS). These properties suggest that it can improve the maturation rate of oocytes and developmental ability of embryos, which are key parameters in animal breeding. In this study, the effects of LEO on in vitro maturation and early embryonic development in sheep oocytes were evaluated. Among various doses examined (0, 10, 20 and 40 μM), a dose of 20 μM was optimal with respect to the oocyte maturation rate. Compared with estimates in the control group, GSH levels and mitochondrial membrane potential of sheep oocytes treated with 20 μM LEO were significantly higher, and 40 μM LEO would affect oocyte maturation. Additionally, ROS levels were significantly lower, expression levels of the antioxidant genes CAT and SOD1 were significantly higher, and there was no significant difference in GPX3 expression. The Bax/Bcl-2 ratio and Caspase-3 expression were significantly reduced in the 20 μM LEO group. During early embryonic development in vitro, the cleavage rate and blastocyst rate were significantly higher in the 20 μM LEO treatment group compared to other groups. GSH levels and mitochondrial membrane potential were significantly higher, while ROS levels were significantly lower, and expression levels of the antioxidant genes CAT, GPX3 and SOD1 were significantly higher in eight-cell embryos treated with 20 μM LEO than in the control group. The Bax/Bcl-2 ratio and Caspase-3 levels were significantly decreased. In summary, LEO can reduce the effect of oxidative stress, improve the oocyte maturation rate and enhance embryonic development.

Effect of energy source during culture on in vitro embryo development, resistance to cryopreservation and sex ratio

The aim of this work was to evaluate whether minimizing the glucose concentration during culture or replacing the hexose with other energy substrates and/or embryotrophic compounds would affect the in vitro development, the resistance to cryopreservation and the sex ratio of bovine embryos. In vitro matured and fertilized oocytes were randomly assigned to 4 groups for in vitro culture, that differed in the energy substrates included: group A) 1.5 mM glucose, as in standard SOF; group B) 0.15 mM glucose; group C) 0.125 mM G3P, in the presence of 0.15 mM glucose and group D) 0.34 mM citrate, in combination with 2.77 mM myo-inositol. Blastocysts were evaluated on day 7, then vitrified by cryotop in 16.5% DMSO, 16.5% EG and 0.5 M sucrose and warmed in decreasing concentration of sucrose (0.25 to 0.15 M sucrose). The survival rates were assessed after 24 h in vitro culture. Finally, the blastocysts produced were sexed by PCR. An increased blastocyst rate was recorded in groups B, C and D, i.e., when glucose concentration was reduced, compared to group A (28.2, 41.0, 35.7 and 35.8, respectively in groups A, B, C and D; P < 0.01). However, the embryos cultured in group D showed the slowest developmental speed, indicated by the lowest percentage of advanced stage-embryos (expanded and hatched blastocysts) out of the total blastocysts (56.1, 45.8, 56.9 and 31.8 %, respectively in groups A, B, C and D; P < 0.01). Furthermore, survival rates after 24 h culture of vitrified-warmed blastocysts also decreased in group D (73.3, 73.1, 71.4 and 58.4%, respectively in groups A, B, C and D; P < 0.01). Interestingly, in group D a higher percentage of female embryos was obtained compared to group A, with intermediate values in groups B and C (45.6, 53.4, 50.0 and 61.5%, respectively in groups A, B, C and D; P < 0.05). In conclusion, it was demonstrated that the energy substrate during in vitro culture affects both the production and the viability of blastocysts. Furthermore, manipulating the metabolic profile of embryos during in vitro culture may have an impact on sex ratio.

A prospective randomized sibling-oocyte study of two media systems for culturing cleavage-stage embryos-impact on fertilization rate

PURPOSE

Although several media systems have been developed, data from prospective randomised clinical studies are still lacking. In the present study we compared the effects of 2 different media systems on embryo morphology and development at days 2/3 using sibling oocytes.

METHODS

In this prospective sibling-split trial, 1206 oocytes from 110 women were divided via alternate allocation to fertilization and culture in media system A (G-IVF (TM) v5 PLUS/ G-1(TM) v5 PLUS) or for fertilization and culture in media system B (Universal IVF medium/EmbryoAssist (TM)).

RESULTS

The use of media system A significantly increased the normal fertilization rate (73.5% versus 67.2%; p = 0.030) and embryo utilization rate (55.5% versus 42.9%; p = 0.001), whereas polyploidy and embryo quality were similar in the two groups.

CONCLUSION

The different impacts on fertilization and early embryo development between the two commercially available and commonly used media systems show the importance of evaluation of the efficacy of existing sequential culture media and the need to further improve media for in vitro development of human embryos.

Effects of fructose supplementation in chemically defined protein-free medium on development of bovine in vitro fertilized embryos

The present study evaluated the possible embryotrophic role of fructose supplementation in potassium simplex optimization medium (KSOM) on preimplantation development of bovine in vitro matured and fertilized (IVF) embryos under chemically defined conditions. In Experiment 1, the rates of cleavage (74.0-75.5%) and blastocyst formation (21.0-24.5%) were not affected by the supplementation of fructose in KSOM in absence or presence of glucose. In Experiment 2, the rates of cleavage (71.7-77.3%) and blastocyst formation (19.9-26.3%) did not differ significantly among the concentrations (0.0, 0.2, 1.5, 3.0, 5.6mM) of fructose supplementations in KSOM in presence of glucose. Moreover, the number of total ICM and TE cells, and percentage of ICM to total cell in blastocysts did not differ significantly among the concentrations of fructose supplementations in presence of glucose. In Experiment 3, the rates of cleavage (67.3-74.7%) and blastocyst formation (14.4-19.3%) did not differ significantly among the concentrations (0.0, 0.2, 1.5, 3.0, 5.6mM) of fructose supplementations in KSOM in absence of glucose. Although the number of total and ICM cells, and percentage of ICM to total cells in blastocysts did not differ significantly among the concentrations of fructose supplementations, 1.5mM fructose supplementation in absence of glucose had significantly (P<0.05) higher number of TE cells (106.2) than that of 5.6mM (84.0) supplementation. The study indicates that, fructose up to 5.6mM concentration can be used as an alternative for energy substrate in culture media without any detrimental effect on pre-implantation development in bovine IVF embryos.