Effects of BOEC and VERO co-culture systems on bovine early development
Résumé
Embryo development is known to be impacted by its environment and especially by oviductal secretions in vivo. In cattle, embryo co-culture with bovine oviduct epithelial cells (BOEC) has been developed to mimic the in vivo oviduct/embryo crosstalk. However, whether BOEC had a specific impact on embryo transcriptome hasn’t been investigated yet. We thus compa-red bovine embryos co-cultured with BOEC to embryos co-cultured with VERO cells (a kid-ney epithelial cell line from monkey). Control embryos were obtained in SOF medium + 5% Fetal Calf Serum (FCS) at 5% O2. Because co-culture systems require 20% O2, embryos cul-tured at 20% O2 in SOF + 5% FCS were included as an additional control. No impact of co-culture systems was observed on timing and developmental rates. 16-cell stage embryos and day 8 blastocysts' transcriptomes were analyzed on a new customized bovine microarray (GPL21734). Comparing the two co-culture conditions revealed only 14 and 10 differentially expressed transcripts respectively at 16-cell and blastocyst stages suggesting almost no diffe-rence induced by the type of co-culture. Nevertheless, BOEC or VERO cells induced differential expression of 83 and 51 transcripts respectively when compared to 5% O2 and 218 and 309 transcripts respectively when compared to 20% O2 in 16-cell embryos and 192 and 229 transcripts respectively when compared to 5% O2 and 542 and 881 transcripts respectively when compared to 20% O2 in blastocysts. A large proportion of the transcripts affected by BOEC presence were also impacted by VERO cells. Several biofunctions relative to cell cycle regulation and lipid metabolism were impacted by both cell types when compared to culture in SOF without feeder cells. Collectively, co-culture systems, using BOEC or VERO cells, induce weak and closely related modifications of embryos transcriptome without improvement of cleavage and blastocyst rates when compared to standard 5% O2 culture conditions.