Secretome derived from different cell lines in bovine embryo production in vitro

The present study investigated the effects of conditioned medium (CM), composed of microvesicles (MVs) and soluble factors present in the supernatant (SN), of bovine endometrial and amniotic cells on embryo quality and rate of blastocyst production. Presumptive zygotes were randomly assigned on Days 1, 3 and 5 after fertilisation to synthetic oviducal fluid with amino acids (SOFaa; control) or to SOFaa supplemented with either 20% endometrial or amniotic CM, 20% SN or 100×106MVsmL-1. Embryos were evaluated on Day 7. For groups supplemented with MVs derived from either endometrial or amniotic cells on Day 1 of culture, blastocysts had developed, but at a lower rate than in the control group. Blastocysts had developed in all groups in which endometrial or amniotic cell-derived CM or MVs were added on Day 3 of culture, but the rate of blastocyst development was significantly lower in both CM groups than in the MVs groups. The addition of all secretome fractions (CM, MVs and SN) derived from either bovine endometrial or amniotic cells on Day 5 of culture resulted in blastocyst production, but only amniotic MVs resulted in a blastocyst production rate comparable to that in the control group. Supplementation of SOFaa on Day 5 resulted in a qualitatively higher number of inner cell mass cells compared with the control group only for the amniotic CM and MVs groups. At day 7, these data were confirmed by RT-qPCR evaluation of genes (Bcl-2-associated X protein (BAX) and glutathione peroxidase 1 (GPX1) involved in apoptosis and protection against reactive oxygen species. In conclusion, of the different secretome fractions tested, only amniotic MVs added to SOFaa resulted in better outcomes than in the control group.