Fig 1: Human Gut Chip microfluidic culture device.a Schematic showing the positions of the human intestinal epithelium and endothelium when initially plated on opposite sides of the matrix-coated porous membrane within the two-channel microfluidic device (left), and how this progresses to form a villus epithelium in the top channel interfaced with a planar endothelium that forms a lumen in the bottom channel (middle). A representative immunofluorescence confocal micrograph visualizing a cross-section of the Gut Chip device with the villus intestinal epithelium stained for villin (green) to visualize the apical brush border, and the planar endothelium stained for VE-cadherin (red) to visualize adherens junctions, is shown at the right (bar, 100 µm). b Microscopic views showing the villus morphology of the human Caco-2 intestinal epithelium cultured for about 5 days in the Gut Chip with flow (30 µl h-1) and cyclic strain (10% at 0.15 Hz), when viewed from above by DIC imaging (left; bar, 50 µm) or by immunofluorescence staining for the tight junction protein, ZO-1 (green, middle; bar, 50 µm) and villin (green, right; bar, 100 µm). Blue and gray indicate DAPI-stained nuclei. c Microscopic views showing the planar morphology of the human endothelium cultured under identical conditions as in b, when viewed from above by phase contrast imaging (left; bar, 50 µm) or immunofluorescence staining for the endothelial cell junction-associated proteins PECAM-1 (green, middle; bar, 50 µm) and VE-cadherin (red, right; bar, 200 µm). Blue indicates DAPI-stained nuclei