132 - Developmental Trajectory of Extracellular Vesicles from the Lungs of Preterm Infants

Extracellular vesicles (EVs) have been identified as important mediators of cellular communication. Because lung development requires vast cellular and structural changes that rely on cellular communication, EVs may be both markers and mediator of normal development and of bronchopulmonary dysplasia (BPD) after preterm birth.


Objective:

To characterize EVs across lung development.

Design/Methods:

TAs were collected from infants born between 22 and 35 weeks gestation intubated for in/out surfactant or respiratory failure. TA were analyzed for EVs with electron microscopy (EM), nanoparticle tracking analysis (NTA), and bead-based flow cytometry with the MACSPlex Exosome Kit. We queried a single-cell transcriptomic atlas of mouse lung development for EV marker expression.

Results:

TAs were collected from 34 patients, with 27 samples containing detectable EVs. For analysis, patients were divided into two groups based on developmental stage, late canalicular (22w0d to 26w6d) and saccular (27w0d to 34w6d). EM showed EVs of varying sizes in TAs. NTA revealed infants in the late canalicular stage had larger mean and median EV diameter. Bead-based flow cytometry found an abundance of the EV-enriched tetraspanins CD9, CD63 and CD81 across GA and particularly high levels of EVs carrying CD326 (EpCAM) and CD133 (Prom-1), consistent with the detection of abundant EVs derived from epithelial cells. Higher levels of CD24⁺ EVs were detected in samples from the late canalicular vs. saccular stage (p=0.0095). There also appeared a trend towards higher levels of CD14⁺ in EVs in the late canalicular stage (p=0.0664). Among infants that went on to develop BPD, higher levels of CD24⁺ (p=0.0186) and CD14⁺ (p=0.0372) EVs were detected. Query of epithelial cells from a developmental atlas revealed abundant levels of EV marker gene expression in epithelial cells across analogous stages in mouse lung development.

Conclusion(s):

We have identified a developmental trajectory of enriched CD24⁺ EVs during early lung development and an association of CD24⁺ EVs with developmental stage and BPD and  CD14⁺ EVs with risk of BPD, independent of GA. This work lays a foundation to query the biologic function of EVs during lung development, with the overall goal of identifying therapeutic agents for restoring lung development in premature neonates.