Exosomal miR-17-5p from human embryonic stem cells prevents pulmonary fibrosis by targeting thrombospondin-2

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible lung disease characterized by pulmonary fibrosis and lung dysfunction, ultimately leading to respiratory failure. Many preclinical studies have investigated the therapeutic potential of stem cell-derived exosomes in this disease, particularly mesenchymal stem cell-derived exosomes. However, the effects of embryonic stem cell-derived exosomes in IPF remain unclear. We established a bleomycin (BLM)-induced pulmonary fibrosis mice model and administered human embryonic stem cell exosomes (hESC-exo) from the first day after BLM treatment. RNA-seq was used to screen for the potential therapeutic targets of hESC-exo in fibrotic lungs. RNA-seq facilitated exploration of the mechanism by which hESC-exo combated BLM toxicity in the lung. To screen the key genes for alleviating pulmonary fibrosis of hESC-exo, we focused on investigating differences in the mRNA expression profiles between BLM-treated lungs with or without hESC-exo-treatment. Pairwise Venn analysis extracted 29 overlapping upregulated, and 14 overlapping downregulated, genes between the BLM+PBS group and the normal saline (NS)+PBS and BLM+exo groups. The overlapping differentially expressed genes (DEGs) (29 plus 14), as the key candidate genes for hESC-exo to alleviate pulmonary fibrosis, were subjected to bioinformatics analysis, and the results indicated that they were mainly involved in the ECM, ECM organization, positive regulation of natural killer cell-mediated cytotoxicity, etc., processes that are involved in the following pathways: ECM-receptor interaction, cytokine-cytokine receptor interaction, focal adhesion, cell adhesion molecules, etc. Results indicated hESC-exo administration notably alleviated inflammation, removed deposited collagen, and rescued alveolar architecture in the lungs of BLM-induced mice. In vivo and in vitro tests revealed that hESC-exo-derived miR-17-5p directly bound thrombospondin-2 (Thbs2) to regulate inflammation and fibrosis; thus, hESC-exo protected against BLM toxicity in the lungs via the miR-17-5p/Thbs2 axis. These results suggest a promising new treatment for fibrosis-associated diseases.