Abstract/Summary

Fetal lung underdevelopment, also known as pulmonary hypoplasia, is characterized by decreased lung growth and maturation. The most common birth defect found in babies with pulmonary hypoplasia is congenital diaphragmatic hernia (CDH). Despite research and clinical advances, CDH babies still have high morbidity and mortality rates, which are directly related to the severity of lung underdevelopment. To date, there is no effective treatment that promotes fetal lung growth and maturation. Herein, we describe a stem cell-based approach that enhances fetal lung development via the administration of extracellular vesicles (EVs) derived from amniotic fluid stem cells (AFSCs). Using fetal rodent models of pulmonary hypoplasia (primary epithelial cells, organoids, explants, and in vivo), we demonstrated that AFSC-EV administration promotes branching morphogenesis and alveolarization, rescues tissue homeostasis, and stimulates epithelial cell and fibroblast differentiation. We confirmed this regenerative ability in human models of lung injury, where human AFSC-EVs obtained following good manufacturing practices restored pulmonary epithelial homeostasis. Investigating EV mechanism of action by tracking AFSC-EV cargo transfer, profiling EV protein and RNA content, and sequencing target lung epithelial cells, we found that AFSC-EV beneficial effects were exerted via the release of RNA cargo. Particularly, miRNAs that regulate the expression of genes involved in lung development, such as the miR17~92 cluster and its paralogues, were highly enriched in AFSCEVs and were increased in AFSC-EV-treated primary lung epithelial cells compared to untreated cells. Our findings suggest that AFSC-EVs hold regenerative ability for underdeveloped fetal lungs, demonstrating potential for therapeutic application in patients with pulmonary hypoplasia.