Acrolein measurement and degradation in Dulbecco's Modified Eagle Medium: an examination of in-vitro exposure metrics

Acrolein is a reactive α,β-unsaturated aldehyde known for its adduction to endogenous biomolecules, resulting in initiation or exacerbation of several disease pathways. In-vitro systems are routinely used to elucidate the cytotoxic or mechanistic role(s) of acrolein in pathogenesis. Nevertheless, the half-life of acrolein in biological or in-vitro systems, e.g. blood or culture media, has not been well characterized. Since in-vitro cytotoxic and mechanistic investigations routinely expose cultures to acrolein from 1 hour to 72 hours, we aimed to characterize the half-life of acrolein in culture medium to ascertain the plausible exposure window. Half-life determinations were conducted in low-serum DMEM at room temperature and 37 °C, both with and without H9c2 cells. For quantitative assessment, acrolein was derivatized to a fluorescent 7-hydroxyquinoline method validated in-house and assessed via fluorescent spectroscopy. In closed vessel experiments at room temperature, acrolein in DMEM was reduced by more than 40% at 24 hours, irrespective of the initial concentration. Expectedly, open vessel experiments demonstrated accelerated depletion over time at room temperature, and faster still at 37 °C. The presence of cells tended to further accelerate degradation by an additional 15-30%, depending on temperature. These results undermine described experimental exposure conditions stated in most in-vitro experiments. Recognition of this discrepancy between stated and actual exposure metrics warrant examination of novel alternative objective and representative exposure characterization for in-vitro studies to facilitate translation to in-vivo and in-silico methods.