FIGURE 6.

Tissue inhibitor of matrix metalloproteinase-3 (TIMP-3) inhibits vascular endothelial growth factor (VEGF)-mediated human retinal microvascular endothelial cell (HRMEC) migration, chemotaxis and proliferation. A scratch was made in confluent monolayers of overnight starved HRMECs with a micropipette tip. Subsequently, the cultures were pre-incubated with TIMP-3 (100 ng/ml) or dilution medium for 1 h before stimulation with dilution medium or vascular endothelial growth factor (VEGF) (50 ng/ml) for 24 h. Cells were visualized using an inverted microscope. Three independent experiments were performed. Each experiment was done in triplicate and 6–8 independent field images were taken for the migration analysis which was done by using image J software. In the figure one representative image is shown [panel (A)]. Results are expressed as median (interquartile range). Kruskal-Wallis test and Mann-Whitney test were used for comparisons between three groups and two groups, respectively. *p < 0.05 compared with untreated cells. ^#p < 0.05 compared with VEGF-treated cells. Chemotaxis and proliferation of HRMECs stimulated with 10 ng/ml VEGF was modulated by a 30-min pre-incubation with TIMP-3 (10 or 100 ng/ml). Cell migration was monitored using the xCELLigence RTCA-DP system. The median (interquartile range) percentage of inhibition of VEGF-induced chemotaxis [panel (B)] or proliferation [panel (C)] is shown. In total five chemotaxis experiments were performed and conditions were tested in duplicate or triplicate within 1 experiment. For proliferation, 6 experiments were performed and conditions were tested at least in triplicate within 1 experiment. *p < 0.05; Mann-Whitney test (compared with VEGF).