Pre-validation of the ex vivo model precision-cut lung slices (PCLS) for prediction of acute inhalation toxicity

Tissue models for respiratory toxicity are mainly focused on prediction of toxicological outcomes such as organ injury, sensitization and inflammation. Nevertheless, the regulatory application of alternatives to inhalation toxicity studies has lagged behind other routes of administration. The goal of this project was the standardization and prevalidation of precision-cut lung slices (PCLS) as ex vivo alternative to reduce animal numbers used in inhalation toxicology. The project was conducted in three independent laboratories. In all laboratories, PCLS were exposed to 20 substances. Toxicity was assessed by LDH and WST-1 assay. In addition, protein content and IL- were measured. Dose-response curves were fitted and EC50 values were calculated. This presentation shows the final results for all 20 chemicals. More than 900 dose-response curves were analysed. Log10[IC50 (M)] showed best intra-laboratory consistency for WST-1 and BCA assays. WST-1 and LDH indicated toxic effects for majority of the substances. Some substances induced IL-1. The reproducibility within the laboratories was acceptably low. The results show (i) that the technique is transferable and (ii) that binary prediction model provides promising results with a specificity of 0.7 and sensitivity of 0.9. The presentation will give an overview about the current use of lung tissue in inhalation toxicity.