Use of reverse transcription-polymerase chain reaction to detect embryonic interleukin-1 system messenger RNA in individual preimplantation mouse embryos co-cultured with Vero cells

In this study, we report a total of 292 mouse embryos cultured on Vero cell monolayers and 77 embryos cultured in medium alone at different preimplantation stages examined individually for embryonic mRNA of β-actin, interleukin-1β (IL-1β), interleukin-1 receptor antagonist (icIL-1ra) and interleukin-1 receptor type I (IL-1RtI) using reverse transcription and two-step polymerase chain reaction (RT-PCR). The rates of blastocyst formation and blastocyst hatching were both significantly higher in embryos co-cultured with Vero cells in comparison with the embryos cultured in control medium (81.2 ± 2.6 versus 42.2 ± 3.7%, P < 0.001; 75.6 ± 2.7 versus 19.2 ± 6.2%, P < 0.001 respectively). We have identified a similar pattern of interleukin-1 family embryonic mRNA transcripts expressed from the compact morula stage through to hatching blastocyst in both control and Vero cell cultured embryos with significantly increased icIL-1ra transcript at hatching blastocyst stage (P < 0.05, P < 0.001 respectively). There was a significant increase in IL-1β mRNA transcripts of embryos at hatching blastocyst stage compared to compact morula stage in Vero cell cultured embryos (P < 0.05). These findings support the hypothesis that the IL-1 system is an important factor in embryo-maternal molecular communication during the implantation process.