Functional characterisation and application of an ex vivo perfusion-superfusion system in murine airways

IntroductionThe aim of this study was to develop two dynamic ex vivo airway explant systems, a perfusion-superfusion system and a ventilation-superfusion system, for the study of toxic airborne substances, such as the prevalent smoke constituent acrolein.MethodsMouse isolated tracheal segments were perfused with physiological media or ventilated with humidified air at 37 °C to mimic dynamic flow conditions, and superfused with media over the exterior surface. At selected time points, the histological and functional integrity of segments was evaluated. The perfusion-superfusion system was subsequently used to examine mucin secretory responses elicited by acrolein in airways in which mucous metaplasia had been induced with lipopolysaccharide (LPS; 1 μg ml− 1) prior to 24 h of media perfusion, followed by stimulation with acrolein or ATP for 15 min. Epithelial mucin levels were determined by quantitative analysis of periodic acid-Schiff's reagent (PAS)-stained sections.ResultsEpithelial morphology was successfully preserved in the perfusion-superfusion and ventilation-superfusion systems for at least 24 h and up to 18 h, respectively. At these time points, the contractile and relaxation responses of perfused and ventilated tracheal segments to carbachol, the neuropeptide substance P, and the prostanoid PGE2 were also preserved. Using the perfusion-superfusion system, acute exposure to acrolein caused a dose-dependent reduction in the levels of PAS-positive mucin stores induced by LPS, consistent with mucin secretion.DiscussionBoth the perfusion-superfusion and ventilation-superfusion systems successfully preserved the viability of mouse isolated tracheal segments on a histological and functional level, and the perfusion-superfusion system was used to characterise the mucin secretory responses elicited by acrolein. Thus, this system may be a useful model through which to conduct further toxicological studies in mammalian airways.