Transwell Assay for Podocyte Barrier Assessment

Cellular barrier properties were assessed using assessment of TER across confluent podocytes with Millicell-ERS (MERS00002, Millipore, Darmstadt, Germany) [23 (link)]. A 24-well transwell system (Greiner Bio-One, 0.4-mm pore size, 6.5-mm diameter, transparent, Costar) was inserted into the 24-well plate. Podocytes were plated in transwell chambers. The volumes of culture medium were 100 and 600 μL in the upper and lower compartments, respectively, in which cells were allowed to grow for 2 days (considered day 0). The resistance (R sample) was measured; the value for the blank well represented the blank resistance (R blank). The following calculation was performed: epithelial monolayer resistance = (R sample-R blank) * effective membrane area (the area of a 24-well transwell chamber is 0.336 cm²).