Chronic Obstructive Pulmonary Disease (COPD) is a chronic respiratory disease characterized by a progressive decline of lung function. The limitation of expiratory airflow primarily affects distal airways, which show early signs of remodelling, inflammation and obliteration. The limited relevance of 2D cell models and lack of 3D models mimicking small airway features hinder early pathophysiological understanding and drug discovery. We have previously developed a 3D mesenchyme-free tubular “bronchioid” model.

Here, we aimed to incorporate bronchial smooth muscle (BSM) cells within the bronchioid model to investigate epithelial-mesenchymal interactions in COPD. We used a tubuloid cell-based assay and human bronchial epithelial and smooth mucle cells derived from clinical samples.

Spatially control of dual cell encapsulation was required to obtain a tubular epithelial structure surrounded by a peripheral concentric layer of BSM cells, mimicking bronchial topology. Adding the BSM cell population improved the robustness of the system. BSM cells exhibit active proliferation during the first two weeks before becoming largely quiescent, whereas BECs continue to proliferate throughout the culture period. We observed a greater persistence of basal epithelial cells in the bi-compartment bronchioid compared to the mesenchyme-free model, along with a shift toward more secretory cells. Calcium imaging following carbachol stimulation confirmed the ability of BSM cells to respond to a cholinergic stimulus. Bronchoconstriction and release, differentiation level and regeneration properties will be next tested in COPD and non-COPD-derived bronchioids.

We conclude that the bi-component bronchioid enables modeling of the distal lung's epithelial-mesenchymal unit and serves as a powerful tool for understanding COPD pathogenesis.