Vascular protection by young circulating extracellular vesicles ameliorates aging-related pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a fatal aging-related disease characterized by aberrant lung remodeling and progressive scarring, leading to organ failure and death. Current FDA approved anti-fibrotic treatments are unable to reverse established disease, highlighting the need for innovative therapeutic approaches targeting novel pathways and cell types. Mounting evidence, including our own, has recently highlighted the pathogenic role of aging-related endothelial abnormalities, including vascular inflammation and oxidative stress, in the progression of lung fibrosis, offering new therapeutic opportunities to block IPF progression. Unexplored, however, are the modalities to restore vascular abnormalities associated with progressive lung fibrosis, representing a critical gap to effective treatments for IPF. In this study, we demonstrate that circulating extracellular vesicles (cEVs) isolated from young mice are capable of reversing the aging-associated transcriptional alterations of the pulmonary vasculature, reducing transcripts associated with innate immunity, oxidative stress and senescence, while simultaneously increasing transcripts linked to endothelial identity. Using the bleomycin model of persistent lung fibrosis in aged mice, we then demonstrate that the pre-treatment with cEVs improves the vascular response to injury and attenuates lung fibrosis progression, as demonstrated by reduced lung collagen content and preserved vascular network and lung architecture. These findings support the efficacy of interventions targeting endothelial aging-associated transcriptional alterations, such as young cEV delivery, in mitigating pulmonary fibrosis progression in animal models of persistent fibrosis and indicate the potential benefits of combined therapies that simultaneously address vascular and non-vascular aspects of IPF.