Beneficial effects of small extracellular vesicles derived from MSC-NTF (NurOwn®) cells on lung inflammation and fibrosis

Background ExMN exosomes are small extracellular vesicles (sEV) derived from mesenchymal stem cells induced to secrete increased levels of neurotrophic and immunomodulatory factors (MSC-NTF cells). Previously, ExMN have demonstrated therapeutic effects in an acute lung inflammation murine model and were therefore hypothesized to have beneficial effects in additional lung conditions and on consequential remodeling and fibrosis. Methods Protective and early intervention effects of sEV produced from MSC or MSC-NTF cells grown in bioreactors were evaluated 2- and 14 -days after bleomycin induced lung injury in mice. Peripheral blood oxygen saturation and body weight were followed and infiltrating immune cells, cytokines and chemokines were measured in the bronchioalveolar fluid (BALF). Lung gene expression and histopathology were analyzed. Additionally, the effects of ExMN were evaluated in four in vitro models, including lipopolysaccharide-exposed BEAS-2B lung epithelial cells, THP-1 macrophage polarization, activated primary peripheral blood mononuclear cell (PBMC) and CD8+ T cells. Results ExMN administered intratracheally or by inhalation demonstrated significant effects in both protective and early intervention models, significantly reducing histological inflammation and fibrosis scores in ExMN treated mice lungs, displaying efficacy as early as 24 h post administration. By day 14, blood oxygen saturation and body weight improved following treatment and infiltrating immune cells, specifically neutrophiles and T cells as well as BALF cytokines were reduced. Lung gene expression analysis demonstrated a transcriptional reversal in 67% of genes that were altered following bleomycin exposure (e.g., Mmp12, Col3a1, Ccl2 and Cd68). Generally, ExMN efficacy was superior to MSC-derived sEV (ExMSC). Moreover, in four in vitro models, ExMN reduced pro-fibrotic and pro-inflammatory activity while enhancing anti-inflammatory responses including decreased TNFα/IFNγ secretion in PBMCs and CD8⁺ T cells, suppression of MMP12 in both M1 and M2 macrophages, attenuation of IL6/CCL2 in M1 and BEAS-2B cells while augmenting IL10/TGM2 in M2 macrophages. Conclusions Collectively, our findings demonstrate that ExMN exerts superior immunomodulatory and protective effects compared to ExMSC and suggest that ExMN is a promising allogeneic therapeutic candidate for treating acute and chronic lung injury conditions. Furthermore, our results indicate that inhalation is a clinically relevant ROA for ExMN and that pre-treatment with ExMN confers protection from lung injury.