Human amnion cell-derived extracellular vesicles in the treatment of bronchopulmonary dysplasia and associated pulmonary hypertension

Abstract

Background & Aim We previously showed that human amnion epithelial cells (hAECs) are a viable source of cell therapy for established bronchopulmonary dysplasia (BPD). This work has culminated in a first-in-human clinical trial in babies with established BPD. In this current study, we sought to assess the therapeutic potential of hAEC-derived EVs (hAEC-EVs) in an experimental model of BPD. Methods, Results & Conclusion Methods Lipopolysaccharide (LPS) was introduced to C57bl6 mouse fetuses intra-amniotically at E16 prior to exposure to 65% oxygen (hyperoxia) at birth. hAEC-EVs were injected intravenously on postnatal day (PND) 4. One cohort of mice were culled on either postnatal day PND7 or PND14, while another cohort were kept in hyperoxia until PND 28, following which they were recovered under normoxia conditions for a further 2 weeks or 6 weeks for cardiovascular assessment. Results The isolated hAEC-EVs had distinct cup shaped morphology with average size of 80-140nm. ALIX, Grp94 and HLA-G were expressed in EVs, and Pathway enrichment analysis showed that endothelin signaling pathway, Wnt signaling pathway, and inflammation mediated by chemokine and cytokine signaling pathway were enriched in hAEC-EVs. In the mouse model of experimental BPD, hAEC-EV administration improved tissue-to-airspace ratio and septal crest density in a dose-dependent manner. hAEC-EVs reduced the levels of inflammatory cytokines such as interleukin (IL)-1β and tumour necrosis factor-alpha (TNF-α) on PND7. The improvement of lung injury was associated with the increase of the percentage of type II alveolar cells (AT2s) at both PND7 and 14. Surprisingly, neonatal hAEC-EV delivery reduced airway hyper-responsiveness, mitigated pulmonary hypertension and prevented right ventricle hypertrophy that associated with BPD-like lung injury at week 6. These improvements persisted till week 10. All these observations showed that HAEC-EVs mitigate the BPD lung injury through decreasing inflammation, activating local AT2 niche and reversing pulmonary artery remodeling. Conclusions hAEC-derived EVs had similar therapeutic effects to hAECs in this mouse model of experimental BPD. hAEC-derived EVs improved lung structure and reduced lung inflammation in a manner similar to that achieved using hAECs. EVs repaired lung injury partly through the activation of local stem/progenitor cells. Furthermore, hAEC-EV administration had long term benefit in improving lung function, preventing pulmonary hypertension and right ventricle hypertrophy.