Epithelial-stromal cell interactions and extracellular matrix mechanics drive the formation of airway-mimetic tubular morphology in lung organoids.

Complex human airway cellular organization where extracellular matrix (ECM) and epithelial and stromal lineages interact present challenges for organ study . Current lung models that focus on the lung epithelium do not represent complex airway morphology and cell-ECM interactions seen . Models including stromal populations often separate them via a semipermeable barrier precluding cell-cell interaction or the effect of ECM mechanics. We investigated the effect of stromal cells on basal epithelial cell-derived bronchosphere structure and function through a triple culture of human bronchial epithelial, lung fibroblast, and airway smooth muscle cells. Epithelial-stromal cross-talk resulted in epithelial cell-driven branching tubules with stromal cells surrounding epithelial cells termed bronchotubules. Agarose- Matrigel scaffold (Agrigel) formed a mechanically tuneable ECM, with adjustable viscoelasticity and stiffness enabling long-term tubule survival. Bronchotubule models may enable research into how epithelial-stromal cell and cell-ECM communication drive tissue patterning, repair, and development of disease.