A low-cost device for measuring TEER at cultivation of epithelial/endothelial cells on inserts.

Background: The barrier properties of epithelial and endothelial cells are usually studied in vitro when cells are cultured on mesh inserts in culture plates, and it is necessary to assess the state of the cell monolayer on the membrane of the inserts before the experiment. Typically, monolayer density is analyzed by passing a fluorescent label through the insert with cells or by measuring the transendothelial resistance (TEER) of the cell layer. Many studies use both methods of assessing monolayer integrity in parallel, depending on the purpose of the study. The TEER method also allows to record early changes in the monolayer state under the action of various substances.

Aim of this work is to demonstrate the possibility of TEER measurements using the proposed device (conductometer) made from freely available components using endothelial/epithelial cells as an example.

Materials and Methods. A device (conductometer) for measuring TEER, created on the basis of easily accessible components, is presented. The device was tested by culturing two cell lines – hybridoma of endothelial origin Ea.hy926 and human colon adenocarcinoma Caco-2. Caco-2 cells were cultured for 22 days and Ea.hy926 cells were cultured for 7 days. The integrity of the cell monolayer and the density of intercellular contacts were evaluated by the TEER value determined by the proposed conductometer, as well as by the fluorescein permeability of the cell monolayer.

Results: The results of TEER measurements using the proposed device and at the same time, the fluorescein permeability of the cell monolayer during the cultivation of Caco-2 and EA.hy926 cells are presented. For Caco-2 cells from the moment of 100% confluence the TEER value gradually increased reaching maximum values by 20-21 days, after which it decreased slightly. The permeability values decreased as the cells were cultured, indicating the formation of dense contacts. For EA.hy926 cells the rise in TEER values are observed on day 3  and decrease was observed on day 7. The results of TEER and permeability obtained by the proposed conductometer have a strong inverse correlation for both cell lines and are in good agreement with each other.

Conclusions. The presented device, made on the basis of simple and affordable components, is similar to commercially available devices and can be used to study the integrity and density of a monolayer in the cultivation of epithelial/endothelial cells, to study the processes of trans/paracellular transport under the action of various substances, as well as in experiments with the co-cultivation of various cell lines.