Ex vivo pulmonary assay applied for screening of toxicity potential of chemicals.

Acute inhalation toxicity testing for chemical classification and labeling has been performed using animal models, however, these models have limited predictibility of the toxicity on the respiratory system. Thus, non-animal models have been emerging as alternatives for preclinical assessment of respiratory toxicity of chemicals, comprising in chemico, in vitro, ex vivo, and in silico approaches. In this study, we characterized and evaluated the applicability of a new ex vivo bovine bronchial model for addressing key aspects of pulmonary toxicity. Standardized bronchial fragments were cultured at an air-liquid interface for seven days showing cell viability, morphology, and function during the ex vivo time of cultivation. Different exposure ways, liquid or aerosol exposure, were also studied using paraformaldehyde (PFA) as a positive control. In a concentration-dependent manner, a decrease in tissue viability was observed for aerosols instead of direct liquid exposure upon tissue surface. Moreover, PFA exposure allowed the addressment of several damage biomarkers, including epithelium thickness, mitochondrial activity, ROS production, and caspase-3 activation. Besides, the bronquial tissue was exposed to chemicals from different UN GHS inhalation toxicity categories and presented a concentration-dependent response for most of the evaluated materials. The proposed airway ex vivo model represents a low-cost and reproducible tool applicable for pulmonary toxicity assessment of chemicals.