Figure 4

Relative effect of [VEGF] on total vessel growth over time. (A) and (B) Effects of [VEGF] alone on total vessel length. Initial number of capillaries was three, and the number of initial sprouts varied from two to six, with branching allowed. Simulation sample size was five values for each concentration at a given time. Growth for this simulation was unrestricted in i- and j-planes, and the dimension of the k-axis was 400 μm. [VEGF] gradients and initial cell activation level ([VEGF] = 0.6 ng/ml) were held constant for all compared [VEGF] concentrations. (C) and (D) Comparison of sprout length changes as a function of VEGF (ng/ml) to experiments using human endothelial cell spheroids on 3D collagen gel. (C) shows fold increase compared to the control in each experiment, while (D) shows absolute changes in vessel length for the same experiments. Values are for growth from a single spheroid. Experiments in references [60–64] were for a mean of 10 spheroids, embedded in a matrix of collagen from rat-tails. Experiments in [60–62, 64] used HUVEC alone in the spheroids, while reference [63] used a coculture of HUVEC and human umbilical artery smooth muscle cells. All experiments used 50 ng/ml VEGF₁₆₅ alone as the stimuli, except [61], where 25 ng/ml VEGF₁₆₅ and 25 ng/ml bFGF were added. Experimental data are shown by the purple bar [60], yellow bar [63], blue bar [61], orange bar [64] and red bar [62].