Background and aim of the study The animal models of congenital diaphragmatic hernia (CDH) have contributed to identify several signaling pathways potentially associated to the pathogenesis of lung hypoplasia. However, due to their in vivo nature, these models can only demonstrate the consequence of the malformation and thus are not adequate to evaluate different factors which may have influence on pulmonary hypoplasia separately. In particular, it is still unclear at what extent physical constraint produced by herniated abdominal viscera affects the lung development.

We aim at developing a novel ex vivo model harnessing an innovative three-dimensional (3D) printing technique to recapitulate the lung development impaired by physical constraint in CDH.

Methods Lungs harvested from E12.5 mouse embryos were embedded in Matrigel solution and maintained in air-liquid interphase (ALI) culture conditions. On the following day (equivalent to E13.5), a 3D structure surrounding the outer surface of the left lobe was built by polymerization of a chemically modified Polyethylene-glycol (PEG) solution, which was added to Matrigel and selectively cross-linked through a two-photon laser.

Main results The 3D structure mimics the physical constraint observed in CDH. Live imaging demonstrates decreased growth and delayed branching impeded by 3D structure. After 4 days of culture, the size of the lobe and the number of epithelial branching of the lung surrounded by 3D structure were significantly decreased compared to the control lungs cultured without physical constraint.

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Abstract 50 Figure 1

Comparison between lung explants with our without a 3D structure

Conclusions We envision our model as an innovative way to investigate the pathogenesis of pulmonary hypoplasia of CDH. This model has a potential to be applied to human embryo, paving the way for a deeper understanding of the molecular pathways implicated in the mechanism of pulmonary hypoplasia.