not-yet-known not-yet-known not-yet-known unknown Supplementary Fig.1. Representative immunofluorescence images of cells on the chip captured on days 1 and 7 (Calcein AM in green, PI in red), alongside a corresponding statistical analysis (n=6). Scale bars, 75 μm. Measurements of TEER on the chip from day 1, 3, 5, 7 (n=5). Representative immunofluorescence images of cells on the chip captured on day 7 (DAPI staining in blue, E-cadherin in green for epithelial cells, and CD31 in red for endothelial cells). Scale bars, 100 μm. Exemplary immunofluorescence images illustrating the co-culture of lung epithelial cells (green stained with PKH 67) and HUVEC (red stained with PKH 26) cells on the lung chip at day 7. Scale bar = 50 μm. Schematic diagram of the alveolar-capillary barrier formed by lung epithelial and endothelial cells.