CULTEX - an alternative technique for cultivation and exposure of cells ofthe respiratory tract to airborne pollutants at the air/liquid interface

The assessment of cytotoxicity of air contaminants such as gaseous or parti culate compounds and complex mixtures has traditionally involved animal exp eriments, due to the difficulties in exposing cell cultures directly to the se substances. New cultivation and exposure techniques enhance the efficiency of in vitro studies, as demonstrated by a new experimental system called CULTEX1 which allows direct exposure of cells at the air/liquid interface. In this case, human bronchial epithelial cells are cultivated on porous transwell membran es in a device allowing intermittent medium supply. The medium is pumped in to a special modular culture unit through the transwell membrane supporting the cells. At certain time intervals, the medium is completely removed and the cells can be maintained and exposed at the air/liquid interface until the next medium supply without loss of viability. In comparison to conventi onal submersed culture conditions, the cells have been grown on transwell m embranes using the new pulse submersion technique. There are no deleterious effects on cell viability due to the direct exposure to airborne pollutant s. Thus, the introduction of these new cultivation and exposure techniques offers new testing strategies for the toxicological evaluation of inhalable soluble and inert substances as well as complex mixtures.