Fig. 1

Effects of mitogens on the cell cycle and cell morphology of fibroblast-like synoviocytes (FLS). Primary rheumatoid arthritis (RA) FLS were serum-starved and stimulated with platelet-derived growth factor (PDGF) or a combination of PDGF and IL-1β. The cells were then harvested and DNA-stained followed by flow cytometry. a Gating strategy identifying live cells and singlets and histogram gating of cell cycle analysis by DNA content. b Representative histograms of FLS in an unstimulated state and upon PDGF stimulation. c Percentage of cells in the G1 and G2/M phase, respectively, in unstimulated FLS and upon stimulation with PDGF (20 ng/mL) for 24 and 48 h, respectively. d Morphology of FLS in 2D culture, before stimulation and after incubation for 48 h with PDGF (20 ng/mL) + IL-1β (2 ng/mL), as visualized by light microscopy. Scale bar 20 μM. e Percentage of cells in the G2/M phase upon PDGF + IL-1β stimulation compared to percentage of cells without stimulation. Values are the mean ± SEM of three different FLS lines. *p < 0.05, **p < 0.01. FSC-A, forward scatter-area; SSC-A, side scatter-area