Fig. 2

Natural killer (NK) cell interaction with decidua parietalis mesenchymal stem/stromal cells (DPMSCs) evaluated by culturing IL-2-unactivated NK cells with DPMSCs at different DPMSC:NK ratios for 24 h, and NK cell cytolytic activity against DPMSCs then assessed using microscopic examination and the xCELLigence real-time cell analyzer. Representative phase contrast microscopic images show untreated DPMSCs (control) with a spindle-like morphology (a), and nonlysed DPMSCs cultured with IL-2-unactivated NK cells (arrows) at ratios of 1:1 (b), 1:5 (c), 1:10 (d), and 1:20 (e) DPMSC:NK. The results of the xCELLigence showed that after 50 h of culture, IL-2-unactivated NK cells did not lyse DPMSCs as shown by the cell index (f) and significantly decreased DPMSC proliferation (growth slope) (g) at all examined NK:DPMSC ratios. Experiments were carried out in triplicate and repeated 10 times using NK cells and DPMSCs prepared from the peripheral blood of 10 different healthy donors and 10 different fetal membranes, respectively. Scale bars = 50 μm. *P < 0.05