In vitro MMP12-dependent angiogenesis. (A) Left panel: RT-PCR of MMP12 in control and VEGF-treated ECFCs. Right panel: Western blot analysis of MMP12 revealed in the culture medium of control and VEGF-treated ECFCs. (B) Matrigel invasion of control and VEGF-treated ECFCs, in the absence and in the presence of anti-MMP12 antibody (10 μg/mL), under basal conditions (control), and after VEGF stimulation. Histogram refers to quantification of Matrigel invasion assay obtained by counting the total number of migrated cells/filter. Results are the mean of 3 different experiments performed in triplicate in 3 ECFC preparations and are shown as mean value ± SD. *P < .05, significantly different from control. (C) Capillary morphogenesis of ECFCs using the same experimental conditions described for panel B. The figures are representative of a typical experiment of 3 experiments performed in triplicate in 3 ECFC preparations. Quantification was performed by measuring the percentage field occupancy of capillary projections, taking the control as 100%. *P < .05, significantly different from control. Image acquisition and quantification were performed as described in Figures 1 and 3.