Fetal lung vascular development is disrupted by mechanical compression and rescued by administration of amniotic fluid stem cell extracellular vesicles via regulation of the Hippo signaling pathway.

Postnatal pulmonary hypertension is the biggest treatment challenge and major determinant for poor outcome in infants with congenital diaphragmatic hernia (CDH). CDH lungs are hypoplastic and exhibit vascular remodeling, whose pathogenesis remains poorly understood. Using a novel micro-static compression system, herein we found that mechanical compression induces vascular remodeling and downregulation of key angiogenic markers in rat and human fetal lung models, with similar features observed in CDH fetal lung autopsy samples. These fetal lung vascular changes are reversed back to normal upon administration of extracellular vesicles derived from amniotic fluid stem cells (AFSC-EVs), a regenerative approach previously shown to restore lung branching morphogenesis and epithelial differentiation in CDH models. Exploring pathways that are dysregulated in CDH lungs and involved in mechanotransduction, we found that compressed fetal lungs had altered expression of Hippo signaling factors that was restored upon AFSC-EV administration. We found that AFSC-EV cargo contains some miRNAs involved in lung vascular development and Hippo pathway, indicating that AFSC-EV regenerative effects is associated with the delivery of specific miRNAs. This study uncovers the role of mechanical compression that herniated organs exert on CDH fetal lungs and proposes a new cell-free strategy to restore normal fetal lung vascular development.