A microfluidic tool for real-time impedance monitoring of in vitro renal tubular epithelial cell barrier

The cell barrier is built to delineate tissue compartments and regulate the substance exchange between different compartments. In this work, we developed a microfluidic tool for real-time impedance monitoring of in vitro renal tubular epithelial cell barrier (RTECB) to follow its formation dynamics and its drug responses. Madin-Darby canine kidney (MDCK) cells were cultured on an artificial basement membrane (ABM) and monitored inside a microfluidic device for up to 10 days. The recorded impedance spectra of the cell layer were analyzed based on an equivalent circuit, giving rise to a set of fitting parameters varying in time. This allowed us to assess the electrophysiological properties of the system and correlate them to the tightness of the epithelial barrier. A calcium switch assay was performed to illustrate the high sensibility of the barrier to biochemical stimuli. Finally, the formation characteristics of the barrier on ABM and conventional transwell membrane were compared, showing significant differences in terms of cell growth dynamics and cell layer stability.