Human mesenchymal stromal cell extracellular vesicles maintain therapeutic miRNA cargo despite exposure to cystic fibrosis bronchoalveolar lavage fluid

BACKGROUND AND AIMS: Human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) and their extracellular vesicles (EVs) reduce lung inflammation and fibrosis in a variety of model systems, including in a Cystic Fibrosis (CF) mouse model. Many components of MSC-derived EVs, including cytokines, antimicrobial peptides, and miRNAs have been implicated in their anti-inflammatory effects. However, a major gap in our knowledge of using MSC as a therapeutic intervention for people with CF (pwCF) is whether the CF airway environment compromises miRNA cargo in hBM-MSC-derived EVs. METHODS: To assess this, hBM-MSCs were exposed to cell culture media (control) or to bronchoalveolar lavage fluid (BALF) obtained from pwCF or healthy controls (HC) and compositional analysis of EV miRNA content was conducted. RESULTS: Thirteen miRNAs (each ≥1% of the total miRNA content) were identified that collectively account for ∼70% of the miRNA content of EVs. These miRNAs were remarkably stable across treatments. To infer potential therapeutic effects, we identified predicted gene targets of these miRNAs and performed pathway enrichment analysis. Gene pathway analysis revealed that many of the 13 miRNAs are predicted to inhibit TLR signaling, NF-κB activation, TGF-β-mediated fibrosis, and cytokine production. CONCLUSIONS: These results indicate that miRNAs secreted by hBM-MSCs in EVs may contribute to the observed anti-inflammatory and anti-fibrotic effects in experimental models and that exposure to CF BALF does not significantly diminish the abundance of the 13 miRNAs.