Fig. 1.

Three-dimensional formation of endothelial sprouts and neovessels in a microfluidic device. (A) Device schematic. Parallel cylindrical channels are encased in a 3D collagen matrix within a microfabricated PDMS gasket and connected to fluid reservoirs. One channel is coated with ECs and perfused with medium and the other channel is perfused with medium enriched with angiogenic factors. (B) Photograph of the device. Zoom shows phase (Upper) and fluorescent (Lower) micrographs of an endothelialized channel. F-actin and nuclei are labeled with phalloidin (green) and DAPI (blue), respectively. (C) Representative confocal immunofluorescence images of sprouting and migrating ECs in response to gradients of different proangiogenic factors: S (i), P (ii), HFMVS cocktail (iv), and MVPS cocktail (v); iii shows a phase image of directed sprouting induced by HFMVS. F-actin and nuclei are labeled with phalloidin (green) and DAPI (blue), respectively. (D) Neovessels in the device are shown in (i) a merged image of a time-lapse movie tracking the position of 3-μm red fluorescent beads perfused through the large channels and neovessels and (ii) a z-projection confocal image of the same vessels. Beads were added to the left end of the parent vessel and flowed through neovessels to the factor source channel. In both images ECs (green) are labeled with DiI. F, bFGF; H, HGF; M, MCP-1; P, PMA; S, S1P; V, VEGF. (Scale bars: 2× zoom-in Insets in C, 50 μm; all other scale bars, 100 μm.)