Fig. 7
Comparison of barrier characteristics of inverted cultures of pmCPECs on filters with 0.4 and 5 μm pores. a The time dependent progression of the transepithelial electrical resistance (TEER) of pmCPECs grown or inverted (abluminal) Transwell filter inserts with 0.4 and 5 μm pores was measured by impedance spectroscopy using the cellZscope device from d3 to d7 in culture. The pmCPECs on both kinds of filters reached a TEER of 100–150 Ω cm2 on d7. The figure shows one experiment with 3 filters per condition and 3 empty filters per condition. The colored lines show the mean TEER values of triplicate measurements surrounded by colored areas, which represent the SD. The area under the curve (AUC; Units: Ω cm2 h) was assessed for a comparison of the overall resistance of the cell layers over time with no significant difference detected. b, c The permeability of the pmCPEC grown on inverted Transwell filter inserts with 0.4 and 5 μm pores for two different small molecular tracers was determined following the TEER measurements in 1 experiment with n = 4 filters per condition. There was no difference for the permeability of Alexa Fluor 680–3 kDa dextran (Pe3kDa) (b) or for 457 Da Lucifer Yellow (PeLY) (c) across the pmCPECs cultured on either type of filter. d Immunofluorescence staining for claudin-1 (Cldn-1), cytokeratin (CK) and nuclei (DAPI) on pmCPEC monolayers grown on the inverted sides of filter inserts with 0.4 and 5 μm pores. The difference in clarity between the pictures is due to different microscopic characteristics of the filters. Scale bar 100 μm. Bars represent the mean permeability coefficients Pe ± SD