FIGURE 2.

NK cell interaction with DBMSCs. NK cell interaction with DBMSCs (evaluated by culturing IL-2 non-activated NK cells with DBMSCs at different NK: DBMSC ratios for 28 h) and NK cell cytolytic activity against DBMSCs were evaluated using microscopic examination and the xCelligence real-time cell system. Representative phase contrast microscopic images show that untreated DBMSCs (control) have a spindle-like morphology (A) Non-lysed and intact DBMSCs (arrow) cultured with IL-2 non-activated NK cells are shown at NK: DBMSC ratios of 25:1 (B), 50:1 (C), and 100:1 (D) The results of the xCelligence showing that after 28 h of culture, IL-2-non- activated NK cells did not lyse DBMSCs, as reflected by the cell index (E) and decreased DBMSC proliferation (growth slope) at a NK:DBMSC ratio of 100:1, relative to untreated DBMSCs (control), *P< 0.05, (F). Experiments were performed in triplicates and repeated 10 times using NK cells and DBMSCs prepared from the peripheral blood of 10 healthy donors and 10 normal human full-term placentae, respectively. Scale bars: 50 µm.