Addition of steroids to embryo-uterine monolayer co-culture enhances embryo survival and implantation in vitro

Abstract

Co-culture with a mixed cell monolayer established from trypsinized uterine tissue increased the numbers of embryos developing in a minimum essential medium beyond the hatching blastocyst stage in the 5-day period of culture to 56.0% (343/613) compared with 30.2% (93/308) for embryos cultured in medium alone. The inclusion of progesterone (3.2 x 10(-6), 3.2 x 10(-5), or 3.2 x 10(-4) M) or oestradiol (3.7 x 10(-5) M) to the co-cultures increased the mean percentage of embryos developing to the advanced stages to 72.7-78.4%. The addition of progesterone (3.2 x 10(-6) M) together with oestradiol (3.7 x 10(-5) M) resulted in additional improvement to a mean of 86.5% (787/910, P less than 0.001) but the combination was without significant effect on embryos cultured in media alone. Blastocyst viability was not impaired by co-culture as assessed in embryo survival following surgical transfer to pseudopregnant recipients. This study confirms the feasibility of establishing co-culture systems to facilitate investigation of pre-implantation events in vitro and highlights a role of steroid hormones in enhancing the capacity of uterine cells to support pre-implantation-stage embryos.