Fig. 2

Effect of different concentrations of curcumin on cell death, viability and apoptosis of hBMSC and OA-CH. Live/dead staining, CellTiter-Blue assay, and Caspase-3/7 assay were used to determine the viability and apoptosis of hBMSC and OA-CH after treatment with different concentrations of free curcumin for 24 h. a, b Vital and dead hBMSC and OA-CH were visualized by fluorescence microscopy after labeling cells with calcein and ethidium homodimers. Living cells were labeled with calcein (green fluorescence) and dead cells were stained with ethidium homodimer (red fluorescence). Scale bar = 200 μm. c–e Quantification of live/dead staining conducted with hBMSC and OA-CH after stimulation with different concentrations of free curcumin (0–100 μM). f–h Quantification of viability and apoptosis assays conducted with hBMSC and OA-CH after treatment with different concentrations of free curcumin (0–100 μM). The 0 μM group without curcumin treatment is defined as control (DMSO only). i Quantification of caspase 3/7 assay conducted with IL-1β-induced OA-CH after treatment with different concentrations of EVs. The OA-CH group (no treatment) is defined as control. Difference to control: *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001; ^#difference between groups: ^#p < 0,05; ^##p < 0,01; 1-way ANOVA with Newman-Keuls multiple comparison test; n = 4