Figure 8: Mesenchymal stem cells (MSCs) prevent pyroptosis in macrophages with ITO-NP, SiO2-NP and MSU exposure.
(a) Schematic diagram indicating the experimental procedures used to examine the effects of MSCs in suppressing pyroptosis, upon exposure of macrophages to ITO-NPs, SiO2-NPs or MSU. (b) Cytometer analysis of MSCs shows cells negative for hematopoietic markers CD14, CD34 and CD45, but positive for MSC markers CD73, CD90, and CD105; 1 representative histogram in 4 for each marker is shown. (c) TEM of MSCs shows large cells with a clear cytoplasm and eccentric nucleus; 1 representative image in 3 is shown; original magnification ×1500. (d) MSCs appear on TEM as poorly capable of ITO-NP uptake (black arrow) at 12 h post-exposure; 1 representative image in 3 is shown; original magnification ×500. (e) TEM of MSCs co-cultured with MH-S or PMA-activated THP-1 cells exposed to ITO-NPs. TEM reveals tight cell-to-cell contacts (orange arrow) between MSCs and macrophages containing ITO-NP endosomes (black arrow); original magnification ×3000 and ×8000, 1 representative TEM image in 3 is shown. (f) MSCs co-cultured with MH-S cells exposed to ITO-NPs exhibited LDH release that was inversely proportional to the number of MSCs present. (g) MSCs effect on TNF-α release by MH-S cells exposed to ITO-NPs. (h) MSCs co-cultured with PMA-activated THP-1 cells exposed to ITO-NPs were tested for LDH release, and the release of LDH was inversely proportional to the number of MSCs present. (i) TNF-α release by PMA-activated THP-1 cells exposed to ITO-NPs in co-culture with MSCs. (j) MSCs co-cultured with PMA-activated THP-1 cells exposed to ITO-NPs were examined for IL-10 release. MSCs alone are represented as an empty green circle on the graph. Concentration of ITO-NPs was 500 μg/mL, and exposure time 16 h, unless stated otherwise. (b–j) n = 3–6 ± SEM, *p < 0.05. TEM abbreviations, Cyto = cytoplasm, N = nucleus and E = endosome.
