Early development of bovine embryos is influenced by the origin of feeders during in vitro culture

Abstract

National audienceThe early development of embryo is clearly impacted by its environment and more specifically by the oviduct secretions in vivo. In cattle, an in vitro model of co-culture of bovine oviduct epithelial cells (BOEC) with the embryo has been developed to mimic the in vivo oviduct/embryo crosstalk. On the other hand, several other co-culture systems were previously developed including co-culture with monkey VERO fibroblasts to improve bovine embryo quality. Nevertheless, to the best of our knowledge, no comparison of co-culture systems using BOEC and other cells has been done yet to analyze if there is a specific impact of BOEC on bovine embryo. To answer to this question, we compared the influence of BOEC as well as VERO cells on bovine early development. Because co-culture with BOEC cells require culture at 20%O2, we included two control conditions: embryos cultured at 20%O2 and embryos cultured at 5% O2 in SOF medium + 5% SVF. No difference of cleavage rates were observed. No difference in the timing and rate of 16 cell stage development were observed despite this stage just follows EGA which is very sensitive to environmental conditions. Blastocyst rates are currently analyzed. To have new insight on the embryo quality at the 16-cell stage, a high throughput transcriptomic analysis was developed. Therefore, a new bovine microarray was designed including more than 26 700 transcripts and 250 retroviral EST. Considering an adjusted p value < 0.05, only one gene was differentially expressed between 5% O2 and 20%O2 conditions. Thus, 16-cell embryos seem to not respond to the induced oxidative stress. The direct comparison of the two co-culture conditions revealed only 19 differential expressed genes. Nevertheless, the presence of VERO or BOEC induced differential expression of 125 and 1162 genes respectively when compared to 5% O2 and 1209 and 2186 genes respectively when compared to 20% O2. Interestingly functional analysis using DAVID software pointed to different biological pathways according to the cell types used for co-culture. Further analyses at the blastocyst stage will be necessary to clarify the differential impact of cell types used in co-culture systems on embryo quality