Oligohydramnios compromises lung cells size and interferes with epithelial-endothelial development

BACKGROUND AND OBJECTIVE: Severe oligohydramnios can induce pulmonary hypoplasia. However, the mechanisms by which leaking of fluids cause lung hypoplasia are not well defined. The objective of this study was to characterize a mouse model of pulmonary hypoplasia induced by oligohydramnios.

METHODS: Amniotic sacs were punctured on E14.5 of gestation. Untouched fetuses were used as control. Pregnancy was allowed to continue until E18.5 in which lung tissue was collected and evaluated for morphometry, proliferation, differentiation, apoptosis, and angiogenesis.

RESULTS: Our results found that lung weight, lung to total body weight ratio, and lung water content were reduced in oligohydramnios when compared to controls. In contrast, oligohydramnios did not affect the DNA content. Morphometric studies confirmed that oligohydramnios fetuses had smaller air spaces than control. Interestingly, cells from oligohydramnios fetuses have smaller size and less regular shapes. Oligohydramnios decreased the differentiation of type I epithelial cells and compromised apoptosis and angiogenesis while proliferation was not affected.

CONCLUSIONS: Although, the smaller size of the lung could be explained by a decreased of lung fluids, our data suggest that increased of external compression secondary to severe oligohydramnios can compromise cell size and interfere with epithelial and endothelial development. Type I epithelial cells could have an unrecognized key role in the differentiation of the distal lung mediated by mechanical signals. Pediatr Pulmonol. 2017;52:746-756. © 2017 Wiley Periodicals, Inc.