Sophisticated human airway in vitro models to investigate cell-cell interactions in acute and chronic diseases

Respiratory diseases affect millions of people worldwide. Although animal models have provided valuable insights, they do not fully mimic human airway pathologies. Thus, complex multicellular systems are required as in vitro models for translational research. Vascularization is an essential feature of most tissues. Next to providing perfusion to exchange oxygen and nutrients, endothelial and mesenchymal cells play a crucial role in cell-cell interactions and tissue remodeling in diseases. We have created a 3D model of the airway that uses three human primary cell types: respiratory epithelial, endothelial, and mesenchymal cells in fibrin hydrogels. Cellularized hydrogels are matured in an air-liquid interface for 28 days in specific differentiation medium to support both epithelial differentiation and vascularization. Endothelial cells form hollow capillary-like structures supported by mesenchymal cells. A mature epithelium develops including ciliated, secretory, and basal stem cells. This model can be used to study various diseases, and we have found it to be suitable for investigating the pathophysiology of viral infections such as SARS-CoV-2 with both active and inactivated viruses. By variation of scaffold properties and application of mechanical stimuli such as stretch and compression, different disease states are mimicked to study tissue remodeling and cell response. We developed an innovative tool modeling the respiratory mucosa combining mature epithelium and a vascularized lamina propria. This platform can be utilized for complex disease modeling and personalized medicine, supporting the progressive reduction and replacement of animal studies.