Model validation experiments.

<p>The sprouting percentage (red curve), the angiogenesis level (blue curve), and the fibrinolysis percentage (green curve), are plotted against changes in (A) the initial concentration of fibrin-bound plasminogen (relative units), (B) the decay rate of uPAR (MCS⁻¹), and (C) the decay rate of PAI-1 (MCS⁻¹). The sprouting percentage is the percentage of simulations (out of a 100 simulations) that have an angiogenesis level larger than zero. The angiogenesis level is a measure that simultaneously reflects sprout depth and sprout count, and the mean angiogenesis level is calculated over all simulations that actually formed sprouts. The fibrinolysis percentage is the percentage of the initial fibrin lattice sites that are invaded by the endothelial cells at MCS 6000. (D) Blocking PAI-1 activity increased endothelial sprouting in 3D fibrin matrices in a biphasic manner. hMVECs were seeded confluently on top of 3D fibrin matrices. Subsequently, the hMVECs were stimulated with the combination of FGF-2/TNF<i>α</i> (bT) with or without 100 U/ml trasylol, 25 ug/ml anti-uPAR antibody H2, control mIgG or anti-PAI-1 antibody MAI-2 (n = 4 independent donors, each in triplicate). 7 days after seeding and stimulation with FGF-2/TNF<i>α</i>, tube length was quantified by using Optimas software and expressed as mm/cm² with error bars expressing standard error of the mean. For statistical analysis a one-way ANOVA with Bonferroni post-hoc test was used. * indicates P < 0.05. Error bars of panels A-C are the standard deviation of 100 runs.