A computer-controlled spray-generating and spray-exposure unit called RHINOCON was designed and constructed to offer the possibility of depositing, for example, environmental or pharmaceutical aerosols at the air/liquid interface under realistic exposure conditions. Here, isolated human respiratory cells are chosen to simulate, as far as possible, the in vivo situation. The exposure unit is equipped to hold up to 6 commercially available pump-spray dispensers, which are prepared mechanically for exposure as described in the manufacturer's users' guide. A transwell insert containing the cells is placed opposite each dispenser in a special plate head rst. After starting the program, the spray dispensers are shaken and actuated automatically. The spray is released into an air ow passing over the cells, where the spray droplets are deposited due to their inertia. After exposure, the inserts can easily be removed and processed to measure a variety of cell toxicity parameters, such as cell viability or cell metabolism.
Validation of the experimental setup was performed in an initial set of experiments: (1) by determination of the deposited amount of nebulized test substance on transwell membranes, and (2) by investigation of the cellular reactions of a human respiratory epithelial cell line (HFBE 21) exposed to nebulized hydrogen peroxide or to standard medium as a reference control.Keywords aer os ol, a ir/ liqu id in t er fa ce, expos ur e syst em , h u m a n r espirat or y cells, in vit r o, ph ar m a ceu t ica l a er osol pr od u ct s N owa d a ys, in vit r o st u dies on expla n t s, or isola t ed h u m a n cells, offer a u n iqu e ch a n ce t o st u dy su bs ta n ce effect s dir ectly on h u m a n m a ter ia l wit h ou t u sin g a n im a l st u dies or h u m a n volu n t eer s. N ever t h eless, u n t il n ow, in vest iga t ion s of t h e biologica l effect s in du ced by com plex m ixt u r es on cells of a pr im a r y con ta ct or ga n , lik e th e r esp ir a tor y t r a ct , h a ve been lim it ed. In t h is ca se, it is beca u se t h e subst a n ces a r e, for t h e m ost p a r t ,
