A stretchable and biomimetic polyurethane membrane for lung alveolar in vitro modelling.

The lung alveolus constitutes a morphologically and mechanistically complex tissue that is constantly subjected to cyclic tension and exhibits unique elastic properties. Available materials used to mimic alveolar tissue often lack biomimicry and the mechanical properties required for cyclic tension. Here, we report a fully synthetic fibrous polyurethane scaffold that approximates tissue stiffness, is elastic under breathing simulations and supports long-term culture of alveolar epithelial-like cells. Using electrospinning a fibrous membrane of tuneable thickness, set fibre diameter and small pore size is prepared. When subjected to cyclic uniaxial tension the material retains its elasticity at both low and high frequency mimicking human and mouse breathing. Thanks to the small pore size, lung alveolar cells can be cultured on its apical surface forming an epithelial monolayer. This monolayer can be maintained long term (at least 15 days) and in an air-liquid interface. In the latter conditions, cells differentiate and exhibit expression of surfactant protein A, a constituent of the surfactant layer that plays a key role in lung physiology. Owing to its lung-mimicking characteristics, the electrospun membrane holds the potential to be adapted for breathing lung models.