Different co-culture systems have the same impact on bovine embryo transcriptome

Abstract

During the last few years, several co-culture systems using either BOEC or VERO feeder cells have been developed to improve bovine embryo development and these systems give better results at high oxygen concentration (20%). In parallel, the SOF medium, used at 5% O, has been developed to mimic the oviduct fluid. Since 2010s, the SOF medium has become popular in improving bovine embryo development and authors have started to associate this medium to co-culture systems. Nevertheless, little is known about the putative benefit of this association on early development. To address this question, we have compared embryo transcriptomes in four different culture conditions: SOF with BOEC or VERO at 20% O, and SOF without feeders at 5% or 20% O Embryos have been analyzed at 16-cell and blastocyst stages. Co-culture systems did not improve the developmental rate when compared to 5% O Direct comparison of the two co-culture systems failed to highlight major differences in embryo transcriptome at both developmental stages. Both feeder cell types appear to regulate the same cytokines and growth factors pathways, and thus to influence embryo physiology in the same way. In blastocysts, when compared to culture in SOF at 5% O, BOEC or VERO seems to reduce cell survival and differentiation by, at least, negatively regulating STAT3 and STAT5 pathways. Collectively, in SOF medium both blastocysts rate and embryo transcriptome suggest no influence of feeder origin on bovine early development and no beneficial impact of co-culture systems when compared to 5% O.

Effects of bovine ova density and culture supplements on cleavage and blastocyst development rates of in vitro embryos

“…2 Despite the cells' positive influence on development, the protocol is inefficient, costly, and unsanitary for commercial production. 24 Similar pitfalls, combined with the potential for large offspring syndrome, are observed in a popular strategy of adding fetal serum to culture media. Although it may improve development, there is concern for its potential to spread pathogens and there are regulatory restrictions placed on embryos cultured in animal-based sera.…”

Single-embryo transcriptomic atlas of oxygen response reveals the critical role of HIF-1α in prompting embryonic zygotic genome activation

“…For bovine EGA analysis, we used the following published RNA-seq data set [ 32 ] and acquired EGA genes which significantly upregulated from 8-cell to 16-cell by fold change >1.5. Then, we compared the expression patterns of EGA genes between 5% O 2 - and 20% O 2 -exposed bovine 16-cell embryos by using published RNA-seq data [ 33 ].…”

The interaction between the environment and embryo development in assisted reproduction

“…Due to the large number of signaling molecules and metabolic peculiarities for in vitro cultures of embryos, media with more complex additives are applied that can be used via co-cultures ( Van der Weijden et al, 2017 ; Carvalho et al, 2017 ) or obtained directly from the animal (such as follicular fluid, oviduct fluid, serum) ( Van der Valk et al, 2018 ;). Other, more sophisticated, systems mimic the microtubular anatomy of the Fallopian tube ( Beebe et al, 2002 ).…”