Co-culture with amniotic membrane stem cells for oocyte maturation and early embryonic development in bovine

To improve early embryonic development, many strategies have been studied in various species including bovine. The co-culture of embryos with somatic cells has been known to improve embryo quality during in vitro culture and pregnancy rates compared with conventional culture systems. The co-culture of embryos with oviductal cells which have been used for blastocyst expansion appears to shorten the time needed for synthesis of hCG, early embryo development, and hatching blastocysts. The aim of this study is to investigate whether the co-culture system with amniotic membrane stem cells (bAMS) improves bovine embryonic development competence. In order to investigate the influence of bAMS on early embryo development, bAMS originated from fetal bovine amniotic membranes were used as the feeder layer during in vitro maturation. The rates of matured oocytes, cleavage division, and blastocysts formation were increased (p<0.05) after co-culture with the bAMS compared to the control group. Moreover the rates of oocyte maturation and embryo development were significantly higher with using bAMS below 5 passages. In addition, the GSH level and the total cell number of blastocysts were significantly higher in co-culture group than in those of control group. Apoptotic cells were found more in the control group, and the expression of anti-apoptosis related genes such as Mcl-1 and Bcl-2 were increased after co-culture with bAMS. In conclusion, the present study demonstrated that co-culture with bAMS cells enhances oocyte maturation and embryo developmental competence by increasing GSH level and expression of anti-apoptotic genes with reducing apoptotic cells in bovine embryos. We also found that it is more suitable to use bAMS below 5 passages.