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Fig. 5 | Stem Cell Research & Therapy

Fig. 5

From: Preconditioning human natural killer cells with chorionic villous mesenchymal stem cells stimulates their expression of inflammatory and anti-tumor molecules

Fig. 5

NK cell interaction with MCF-7 breast cancer cells evaluated by culturing IL-2-activated NK cells with pMSCs at different NK to pMSC ratios in a cytolytic experiment. Following 24 h incubation with pMSCs, NK cells were harvested, purified, and then added to MCF-7 cells at a 10NK to 1MCF-7 ratio, and NK cytolytic activity against MCF-7 cells was then evaluated using microscopic examination and the xCELLigence real-time cell system. Representative phase contrast microscopic images showing a complete lysis of MCF-7 cells (no sign of intact adherent MCF-7 and cells were also ruptured as cellular debris were evident in suspension, stars) by untreated NK cells (NK cells were initially activated with 100 U/mL IL-2 for 72 h) (b), pretreated NK cells (pretreated NK cells “pre-NK”: IL-2-activated NK cells precultured with pMSCs) at 15NK to 1pMSC (c), 25NK to 1pMSC (d), 50NK to 1pMSC (e), and 100NK to 1pMSC (f) as compared to MCF-7 cells (arrow) cultured alone (a) within 24 h culture. The results of the xCELLigence show that after 24 h culture, MCF-7 were completely lysed by untreated NK cells and treated NK cells (described above) as reflected by the cell index (g) and growth slope (h). The cell index was reduced almost to zero for MCF-7 co-cultured with NK cells indicating no sign of intact cells. Experiments were carried out in triplicate using the indicated NK to MC7 ratios using NK cells harvested from ten independent NK/pMSC cytolytic assays and MC7 breast cancer cells. Scale bars, 50 μm

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