Determining Airway Cell Polarity by TEER

During culture of WD cells in differentiation medium, the polarity of cells was determined by TEER measurement. The apical and basolateral chambers of inserts were filled with fresh differentiation medium following 21 days of ALI culture, and equilibrated at 37 °C, 5% CO2 for 10 min. TEER values were determined using two Millicell-ERS (MERS00002, Millipore, Burlington, MA, USA) electrodes submerged into the insert medium. WD cells with TEER values > 1000 Ω cm² were considered well-differentiated and met the requirement for subsequent studies of the model (Hiemstra et al., 2018 (link); Huang et al., 2012 ; Min et al., 2016 (link)).