The effect of impactor and impinger airflow on the air-liquid interface of tissue culture inserts
1University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK.
Inhalation is an important route of exposure to particulates; both through medicinal and occupational exposure, and there is increasing awareness of the need for bio-relevant exposure models to assess the biopharmaceutics and toxicology following of particulate exposure. The aim of this study was to assess the potential effects of airflow in the twin stage impinger (TSI), the next generation impactor (NGI) and the Andersen cascade impactor (ACI) on the air liquid interface fluid in tissue culture models; as a guide for selection of appropriate aerosol exposure models for alveolar deposition.
Cell culture medium was applied to Transwell/Snapwells which were placed into the impinger/impactors and subjected to a range of flowrates (30-90 L/min) and volumes (0.5-6.0 L) of air. The weight of the cell culture inserts before and after airflow treatment were recorded to assess fluid phase loss by evaporation and/or ballistic removal from the insert. Fluorescein sodium solution was also applied to inserts and the remaining mass of fluorescein after the airflow was measured by fluorescence spectroscopy to identify ballistic fluid phase loss.
The evaporation and fluorescein studies resulted in loss of mass of cell culture medium and fluorescein with the TSI at airflows above 30 L/min while the NGI and ACI showed minimal loss under all airflow conditions up to 90 L/min. Airflow volume was not observed to be a significant contributor to fluid phase loss from the inserts. The NGI and ACI may be a viable option for aerosol delivery, however, the impact of evaporation on cell health must be determined.