Effect of Human Endometrial Stromal Cell-derived Conditioned Medium on Uterine Natural Killer (uNK) Cells' Proliferation and Cytotoxicity

Problem Human endometrial stromal cells are involved in the regulation of immune cell proliferation, apoptosis, differentiation, and function. In the endometrium, uNK cells are in close contact with stromal cells. The aim of the study was to investigate the effects of human endometrial stromal cells on uNK-cell proliferation and uNK-cell cytotoxicity. Method of study The conditioned medium was derived from the endometrial stromal cells in the proliferative phase, secretory phase, and early pregnancy. The effects of stromal cell-derived conditioned medium on uNK-cell proliferation and cytotoxicity were detected by mitochondrial lactate dehydrogenase-based MTS staining and flow cytometry. Results The stromal cell-derived conditioned medium in both secretory phase and early pregnancy significantly promoted uNK-cell proliferation. Compared with the control group, the uNK-cell cytotoxicity were significantly reduced by conditioned medium in the proliferative, secretory, and decidua groups, but there were no significant differences among these different physiological stages in the inhibiting ability. Conclusion Human endometrial stromal cells may be involved in the regulation of uNK-cell functions through influencing proliferation and cytolytic activity.