Figure 6: Co-culture of blood and fibroblasts synergistically increases secreted MMPs and VEGF.

Concentration of soluble factors in the supernatants of native and alkali-treated Ti surfaces exposed to blood (white bars), blood & fibroblasts (grey bars) or fibroblasts (dark grey bars) 24 h after fibroblast seeding were quantified. Barplots show concentrations of (a) C-terminal peptide of pro-collagen type I (CICP), (b) total Matrix-metalloproteinase (MMP) including pro-MMP amount standardized to fluorescence reference substrate conversion, (c) IL1β, (d) TNFα, (e) TGF-β1 (including latent form) and (f) VEGF. Reported values correspond to mean values ± standard error of the mean for experiments repeated for 8 blood donors. Statistically significant differences between conditions are indicated by (*) for p < 0.05, by (**) for p < 0.01 and by (***) for p < 0.001. Collagen production represented by CICP concentrations originates from fibroblasts, i.e. values are similar between fibroblasts only and blood & fibroblast co-cultures. Alkali-treatment of Ti tends to increase concentrations of IL1β, TNFα, TGF-β1 and MMPs, although co-culture with fibroblasts tamed surface treatment differences of IL1β, TNFα and TGF-β1 concentrations. MMP and VEGF concentrations in fibroblast and blood co-culture conditions were significantly increased compared to blood or fibroblasts alone, suggesting a strong synergistic effect of fibroblasts and blood.