Epithelial Barrier Function Quantification

Electrical impedance (to restrict ionic conductance) imparted by epithelial cultures was measured to quantify barrier function (TJ activity), as previously described^{19 (link),23 (link)}. One difference here was the models were assessed during the entire differentiation process from day 1 (24 h after “air-lift”) to day 32. Briefly, transwell ALI cultures were allowed to acclimatise for 30 min on a 37 °C heating platform (Lecia Biosystems, Mt. Waverley, VIC, Australia) before reading electrical impedance using the EVOM2 Ohm meter (World Precision Instruments, Sarasota, FL, USA). Raw ohm values (n = 3 measures per well) were converted to magnitudes of TEER by subtracting the resistance imparted by an empty transwell and dividing by the surface area of the membrane support (0.33 cm²; Ω.cm²). Five transwells were prepared and assessed per participant per culture type.