Sex-specific differences in the severity of pulmonary hypoplasia in experimental congenital diaphragmatic hernia and implications for extracellular vesicle-based therapy.

Purpose: Amniotic fluid stem cell extracellular vesicles (AFSC-EVs) hold regenerative potential to treat hypoplastic lungs secondary to congenital diaphragmatic hernia (CDH). This study aims to investigate sex-specific differences in pulmonary hypoplasia severity and responses to AFSC-EV administration in an experimental CDH mouse model.

Methods: C57BL/6J dams were fed with nitrofen + bisdiamine (left-sided CDH) or olive oil only (control) at embryonic day (E) 8.5. Lungs were dissected (E18.5), grown ex vivo and treated with medium ± AFSC-EVs that were collected via ultracentrifugation and characterized (nanoparticle tracking analysis, electron microscopy, Western blotting). Pulmonary hypoplasia was assessed via mean linear intercept (MLI). Gene and protein expression changes (Cd31, Enos, Il1b, TNFa) were measured via RT-qPCR and immunofluorescence. Pups were genotyped for Sry.

Results: Experimental CDH showed a male predominance without sex differences for pulmonary hypoplasia severity, fetal lung vascularization, and inflammation. AFSC-EV administration led to improved lung growth (decreased MLI), improved fetal lung vascularization (increased Cd31 and Enos), and decreased fetal lung inflammation (Il1b, TNFa). There was no sex-specific response to AFSC-EV administration.

Conclusion: This study shows sex-independent impaired lung growth, vascularization and fetal lung inflammation in a CDH mouse model. Antenatal administration of AFSC-EVs reverses aspects of pulmonary hypoplasia secondary to CDH independent of the biological sex.