Figure 4.
The efficiency of controlled sprouting (Efcs) induced by ligand patterns
(A and B) Efcs is defined by the formula in (A) and quantifies the level and type of control of the functionalized lines over the spatial location of the endothelial sprouts. Below the formula, a schematic is presented of the patterned lines (red lines), the cell nuclei (blue ellipses), and the corresponding outline of the sprouting front (discontinuous green line). The formula of Efcs then accounts for the amount of cells in the subregion of the ROI in between the ligand lines (Coff, white area) as a percentage of the total amount of cells (Coff + Con) in that ROI. In the definition, Con represents the number of cells in the subregion of the ROI on top of the ligand lines (red area). This definition of Efcs enables the identification of different sprouting patterns and control: Efcs ≈ 50% for random patterning and no control; Efcs ≈ 0% for high control toward positive patterning; and Efcs ≈ 100% for high control toward negative patterning. Comparison of the Efcs between Fc, Jag1, and Dll4 line samples is shown in (B), where boxplots represent N = 31/112/58 ROIs pooled from a total of three Fc/four Jag1/4 Dll4 microchips, respectively. There is a significant difference between the Efcs of Jag1 and Dll4 samples (p < 0.0001) and between the Fc and Dll4 (p = 0.0004).
(C) No significant difference in the number of cells per ROI. In (B) and (C), data are represented as boxplots, where the boxes span from the 25th until the 75th percentile, the whiskers extend down to the 10th percentile and up to the 90th percentile, and the horizontal lines represent the median values.