Fig. 4

a, b Histograms representing high content imaging data for MSC and Beas2B cells exposed to Au or SiO₂ NPs at 150 µg/ml for 24 h (subcytotoxic conditions). The data for a cell size and b FAC size are expressed as mean ± SD (n = 3) relative to the level for untreated control cells (100%). The results for ROS, mitochondrial health and autophagy are presented relative to the level observed for untreated control cells. c Histograms representing the cellular ATP levels of MSC and Beas2B exposed to Au or SiO₂ NPs (150 µg/ml for 24 h) at 1 day and 4 days after NP exposure. Data are expressed as mean ± SD (n = 3) relative to the level for untreated control cells (100%). The degree of statistical significance is indicated when relevant (*p < 0.05; **p < 0.01). d Representative high content images of control MSC (D0) or MSC labelled with the Au or SiO₂ NPs at 150 µg/ml for 24 h and then stained for actin (red) and vinculin (green), a marker for focal adhesion complexes 3, 5 and 6 days after labelling. Scale bars: 50 µm