Barrier Formation and Polarization

Intestinal epithelial cell lines were grown until fully polarized in transwell cultures as already described earlier (21). 3 × 10⁵ cells were grown on 0.4 µM pore sized transwell inserts (Costar). The culture medium was renewed every third day. The TEER was measured by a chopstick electrode with Volt/Ohm meter (World Precision Instruments). TEER values are reported as Ω*cm², i.e., the resistance in Ohm multiplied by the surface area of the transwell insert. The resistance value for the transwell insert without cells was subtracted as the basal resistance.