Human Recombinant Interleukin-6 and Leukemia Inhibitory Factor Improve Inner Cell Mass Cell Number but Lack Cryoprotective Activities on In Vitro-Produced Bovine Blastocysts

This work explored whether supplementing recombinant human interleukin-6 (IL6), interleukin-11 (IL11), or leukemia inhibitory factor (LIF) improves IVP bovine embryo development, morphology, and cryosurvivability. Embryos were treated from day 5 to 8 post-fertilization with either the carrier only (control) or 100 ng/mL of IL6, IL11, or LIF. Blastocyst formation and stage were determined on day 7 and 8. A subset of day 8 blastocysts was processed for immunofluorescence to count trophectoderm (TE) and inner cell mass (ICM) cell numbers and another subset was slow frozen and stored in liquid nitrogen until thawing. No differences in the blastocyst rate or blastocyst stage of development were detected. Increases in ICM cell numbers were observed for IL6 and LIF but not the IL11 treatment. None of the cytokine treatments applied before freezing affected post-thaw survival, TE or ICM cell number, or cell death 24 h after thawing. In conclusion, supplementing IL6 and LIF improves ICM cell numbers in non-frozen blastocysts, but there was no evidence that any of these cytokine treatments contain cryoprotective properties in bovine embryos.