LUCS (Light-up Cell System)-VALITOX

The LUCS test method (light-up cell system) measures general or basal cytotoxicity in cells of human origin.

The test method uses thiazole orange (TO) as fluorescent dye that passively enters the cells and binds to nucleic acids. In homeostatic cells, efflux transport proteins quickly remove the dye limiting their access to the nucleic acids and keeping the fluorescent levels inside the cells low. Changes in cell homeostasis result in the dye entering the cell massively and binding to the nucleic acids, increasing the fluorescence levels.

There is production of ROS inside live cells by light induction and the fluorescence before and after applying light, both in healthy (untreated) and treated cells is measured. The change in fluorescence levels are higher in untreated cells compared to treated cells, which have lost homeostasis.

The test method is proposed as: 1) a method to describe cytotoxicity, and 2) a method to inform acute oral toxicity, in particular for providing the starting dose for the in vivo acute oral toxicity test as described in OECD GD 129.