Embryonic Development and Implantation Related Gene Expression of Oocyte Reconstructed with Bovine Trophoblast Cells

The temporal progressive increase of interferon tau (IFN tau) secretion from the bovine trophoblast is a major embryonic signal of establishing pregnancy. Here, we cultured and isolated bovine trophoblast cells (BTs) from IVM/IVF oocytes and in vitro produced blastocysts, used them, for the first time, as donor cells for nuclear transfer and compared them whit adult fibroblasts (AFs) as donor cells. BTs were reprogrammed in enucleated oocytes to blastocysts with similar efficiency to AFs (14.5\% and 15.6\% respectively, P <= 0.05). The levels of IFN tau, CDX2 and OCT4 expression in IVF-, BT- and AF-derived blastocysts were analyzed using reverse transcription polymerase chain reaction and reverse transcription quantitative polymerase chain reaction (RT-PCR and RT-qPCR). IVF-produced embryos were used as reference to analyze the linear progressive expression of IFN tau through mid, expanded and hatching blastocysts. RT-PCR and RT-qPCR studies showed that IFN tau expression was higher in BT-derived blastocysts than IVF- and AF-derived blastocysts. Both IVF- and BT-derived blastocysts showed a progressive increase in IFN tau expression as blastocyst development advanced when it compared with AF-derived blastocysts. OCT4 was inversely related with IFN tau expression, while CDX2 was found to be directly related with IFN tau temporal expression. Persistence of high expression of IFN tau and CDX2 was found to be higher in BT-derived embryos than in IVF- or AF-derived embryos. In conclusion, using BTs expressing IFN tau as donor cells for bovine NT could be a useful tool for understanding the IFN tau genetics and epigenetics.