Fig. 4

Secretion of G-CSF by MSCs. Levels of G-CSF were assayed after treating cells from different donors (n = 3 experiments/donor) with different concentrations of TNF-α (a) and IFN-γ (b) for 24 h, which had no significant effect on the secretion of G-CSF. Treatments with IL-1α (c) and IL-1β (d) for 24 h induced a strong increase in the secretion of G-CSF. The youngest donor presented the highest increase in secretion, as measured by ELISA (*p < 0.05, **p < 0.01, ***p < 0.001 vs untreated from same donor), despite all donors showing an increase in the secreted levels of G-CSF. The increased secretion of G-CSF in response to priming with IL-1α (e) and IL-1β (f) is completely inhibited when IL1-Ra (100 μg/ml) is added 10 min prior to the treatment. *p < 0.05, ***p < 0.001 vs untreated; ⁺⁺ p < 0.05, ⁺⁺⁺ p < 0.001 IL-1Ra condition vs cytokine treatment only. Cells from donor 3 were used in the inhibition experiment. G-CSF granulocyte-colony stimulating factor, IFN-γ interferon gamma, IL interleukin, IL-1Ra interleukin-1 receptor antagonist, nd not detectable, TNF-α tumour necrosis factor alpha