Influence of formaldehyde on signaling pathways when used in mammalian cell culture

Formaldehyde is the smallest existing aldehyde, a highly reactive color less gas at room temperature and ubiquitously present in our atmosphere. Because of its reactivity leading to the crosslinking of macromolecules like proteins, it is widely used in industrial applications, but also in cell biology in order to preserve cells and tissues for further analysis. In this work, we show that formaldehyde releasing solutions commonly used for fixation of cells, can diffuse via the gas phase to the neighboring well and influence signaling processes in the therein cultured cells. To analyze this effect, we utilized a stable reporter cell line for YAP signaling or a gene expression-based reporter for activation of the NF-kappaB pathway. Especially the stable reporter cell line can also be used as sensor for bioavailable formaldehyde. The observed impact of formaldehyde on cellular signaling underscores the need for careful planning of experimental protocols and emphasizes the importance of implementing proper controls when utilizing this reagent in cellular signaling analyses.