EMBRYO-CONDITIONED MEDIA ALTER THE EFFECTOR FUNCTIONS OF NATURAL KILLERS IN VITRO

NK cells represent the predominant lymphocyte population in the endometrium. NK cells engage in communication with the embryo during implantation, influencing implantation success. However, there is currently a lack of data in the literature regarding the influence of pre-implantation embryos on NK cell functional activity. The task of NK cells in the uteroplacental contact zone is to control trophoblast invasion, stimulate or limit it. Cytokines secreted by both embryo and NK cells —such as IL-1b, IL-6, IL-8, GM-CSF, and IP-10 — have been shown to stimulate migration and invasion of trophoblast cells Therefore, the purpose of this study was to develop a cellular diagnostic technology for predicting reproductive failure by investigating the effect of spent embryo culture media (ECM) on the cytotoxic activity of NK cells against trophoblast JEG-3 cells in an in vitro cytotoxicity model.

It was found that the death rate of Jeg-3 cells after co-culture with NK-92 cells was higher than the spontaneous death of Jeg-3 cells. Collectively, spent embryo culture media which were not divided into groups based on the quality of the embryos reduced the death of Jeg-3 cells when co-cultured with NK-92 cells. We have established that ECM from grade A (excellent- quality) embryos reduce the effector functions of natural killer cells against JEG-3 trophoblast cells. We assume that the embryos with the highest implantation potential (grade A) secrete factors that suppress NK cell cytotoxicity toward trophoblast cells, thereby promoting embryonic survival and successful implantation. Previously, we detected cytokines affecting NK cell functions IL-6, IL-8, IL-1b, IL-10, IP-10 and GM-CSF secreted by excellent quality embryos into a spent culture medium.

Thus, excellent-quality embryos with the greatest implantation potential secrete factors that modulate NK cell effector functions at the maternal–fetal interface. The method of assessing the quality of embryos using a functional model is generally consistent with the morphological system for assessing the quality of embryos and can be recommended for use in clinical practice.

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