Millicell ers 2 5 ohmmeter

Bronchial epithelial cell layer integrity was evaluated by TEER measurements using a Millicell-ERS 2 V-Ohmmeter (Millipore Co., Bedford, MA) at specified time points. The medium in the apical chamber was added at 1 h before TEER measurement. The electrode was soaked in 70% ethanol and rinsed with culture medium prior to use. TEER was calculated by the following equation [24 (link)]: TEER (Ωcm²) = (R_sample – R_blank) × effective membrane area (cm²).

Bronchial epithelial cell layer integrity was evaluated by TEER measurements using a Millicell-ERS 2V-Ohmmeter (Millipore Co., Bedford, MA). Medium was added to the apical chamber 1 h prior to TEER measurement. The electrode was soaked in 70% ethanol and rinsed with culture medium prior to use. TEER was calculated by the following equation^{19 (link)}: TEER (Ω cm²) = (R_sample − R_blank) × effective membrane area (cm²).

Caco-2 cells (a human colon adenocarcinoma cell line) were preserved in our lab and cultured in DMEM supplemented with 12% (v/v) FBS (FND500, ExCell Bio, Shanghai, China), 1% (v/v) L-glutamine, 1% (v/v) streptomycin–penicillin, and 1% (v/v) nonessential amino acids at 37 °C and 5% CO₂. Caco-2 cells were seeded in 12-well Transwell plates at a density of 2 × 10⁵ cells per well. On the 10th to 21st days, the transepithelial electrical resistance (TEER) of each well was detected using a Millicell ERS-2 V-ohm meter (Millipore, Boston, MA, USA). A cell monolayer with a TEER value higher than 400 Ω × cm² was selected for further work (Figure S1A,B). After 21 days, fluorescein sodium transport permeability in normal and inflammatory modes (IL-1β was added at a final concentration of 10 ng/mL on the 21st day and removed after 2 days of culture [20 (link)]) was measured to be 1.19 μg/h·cm² and 1.71 μg/h·cm², respectively, which verified the integrity of the Caco-2 cell monolayer. Then, the apparent permeability coefficient (Papp) of each well was calculated at time points of 1 h, 2 h, 3 h, and 4 h. Papp values were calculated using the following equation:
where dQ/dt is the transport volume per unit time (μg/s), A is the area of the transport membrane (1.12 cm²), and C is the initial concentration on the AP side (μg/L).

Tissues barrier integrity was evaluated by TEER measurements using a Millicell-ERS 2 V-Ohmmeter (Millipore Co., Bedford, MA, USA) at T0 and T24 after 300 ppm HOCL nebulization. For each well, 3 measures were performed. Briefly, the tissues were equilibrated for about 20 min at room temperature before the measurements. Blank measurements were performed on an empty insert. TEER value was then calculated using the following equation: TEER (Ωcm²) = (Rsample—Rblank) × membrane area (cm²).

At specific time points, the VD-treated airway organoids and the corresponding control cells were brought to room temperature and the medium was changed to fresh medium. After 30 min, TEER measurements were performed using a Millicell-ERS 2 V-Ohmmeter (Millipore, Bedford, MA). According to the guidance of the manufacturer, the TEER was calculated using the following equation: $$\text{TEER}\left(\mathrm{\Omega }{\text{cm}}^2\right)=\left(R_{\text{sample}}-R_{\text{blank}}\right)\times \text{effective membrane area}({\text{cm}}^2).$$
The effective membrane area of the inserts used in this study was 0.3 cm², with a diameter of 6.5 mm.