A human PCLS model of lung injury and repair for discovery and pharmaceutical research.

Background: The Acid Injury and Repair (AIR) model is an ex-vivo model of lung injury and repair, that was previously established using mouse precision-cut lung slices (PCLS). The AIR model provides a bridge between the current in -vitro and in-vivo models to study the effects of lung injury in 3D lung tissue slices. Here, we show that the AIR model can be adapted for use in human tissue as a translational model for discovery research and drug screening.

Methods: To generate PCLS, resected human lung tissue was coated with alginate hydrogel to form an artificial pleura. Lung tissue was inflated by point injecting 3% agarose, followed by generation of 450-500 µM thick slices of tissue. An isolated area of each slice was injured by brief application of 0.1 M hydrochloric acid. AIR-PCLS were then washed and cultured for 48 h before immunostaining to assess proliferating cells (Ki67) alveolar type II/progenitor cell markers (HTII, proSP-C), lipofibroblasts (ADRP) and endothelial cells (ERG). Viability of PCLS was assessed by both MTT assay and Live/Dead staining.

Results: We show that levels of proliferation do not change in response to acid injury. However, there is a significant increase in the percentage of proSP-C and HTII positive cells in the injured regions of AIR-PCLS. We also identify non-epithelial cell populations; lipofibroblasts and endothelial cells in human AIR-PCLS, to demonstrate that other repair relevant cell types can be identified and tracked in the human AIR (hAIR model).

Conclusions: The hAIR model is an effective ex-vivo tool to study early mechanisms of lung repair following injury. By establishing an area of injured tissue adjacent to uninjured tissue, this model mimics the heterogenous pattern of lung injury frequently present in lung diseases. The hAIR model will facilitate mechanistic studies of human lung repair and provides a valuable pre-clinical model for drug testing.