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Fig. 3 | Stem Cell Research & Therapy

Fig. 3

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

Fig. 3

NK cell interaction with pMSCs evaluated by culturing IL-2-activated NK cells with pMSCs at different NK to pMSCs ratios and NK cytolytic activity against pMSCs were then evaluated within 24 h culture using microscopic examination and xCELLigence real-time cell system. Representative phase contrast microscopic images showing untreated pMSCs (control) with typical spindle-like morphology (arrow) (a), unlysed pMSCs cultured with IL-2-activated NK cells (arrow) at 1NK to 1pMSC ratio (b), lysed pMSCs cultured with IL-2-activated NK cells at ratios 15NK to 1pMSC (c), 25NK to 1pMSC (d), 50NK to 1pMSC (e), and 100NK to 1pMSC (f). The lysis of pMSCs was evident as no sign of intact adherent pMSCs, and cells were ruptured as cellular debris were evident in suspension. The results of the xCELLigence showing that after 15 h culture, IL-2-stimulated NK cells did not lyse pMSCs at 1NK to 1pMSC ratio, but pMSCs were lysed at 15NK to 1pMSC, 25NK to 1pMSC, 50NK to 1pMSC, and 100NK to 1pMSC as reflected by the cell index, which showing the cell index was almost zero indicating that pMSCs were not intact (no adhesion and proliferation) (g) and growth slope (h). At 1NK to 1pMSC ratio, pMSC proliferation significantly decreased, *P < 0.05 (g, h). Experiments were carried out in triplicate and repeated for ten times using NK cells and pMSCs prepared from the peripheral blood of ten different healthy donors and ten different normal human term placentae, respectively. Scale bars, 50 μm

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