ABSTRACT
Background Radiation-induced pulmonary fibrosis (RIPF) is a late-stage complication of therapeutic radiation, associated with poor prognosis and limited therapeutic options. Radiation-induced lung injury (RILI) is an early manifestation of RIPF, and intervention of RILI is an effective method for preventing long-term RIPF. Mesenchymal stem cell (MSC)-derived exosomes exhibit regenerative activity in injured lungs and are effective drug-delivery nanoparticles. SARS-CoV-2-S-RBD enables ACE2+ cell targeting of MSC extracellular vesicles. miR-486-5p is a multifunctional miRNA with angiogenic and anti-fibrotic activities and is enriched in MSC-derived exosomes. In this study, we investigated the therapeutic effects of miR-486-5p and SARS-COV-2-S-RBD-engineered MSC exosomes on RIPF in vitro and in vivo.Results Adenovirus-mediated gene modification led to the overexpression of miR-486-5p in umbilical cord MSCs (UC-MSCs), which further enriched miR-486-5p in UC-MSCs-derived exosomes. MiR-486-5p-engineered MSC exosomes (miR-486-MSC-Exo) promoted the proliferation and migration of irradiated MLE-12 cells in vitro and inhibited RILI in vivo. An in vitro assay revealed the occurrence of ferroptosis, a major form of cell death during radiation injury, indicated by the upregulated expression of fibrosis-related genes. miR-486-MSC-Exo effectively reversed these changes. MiR-486-MSC-Exo strongly reversed the upregulated expression of MLE-12 fibrosis-related genes induced by TGF in vitro and improved pathological fibrosis in the RIPF model in vivo. The distribution of RBD-VSVG-MSC exosomes labeled with DiR dye in hACE2CKI/CKI Sftpc-Cre+ mice demonstrated that the fluorescence of RBD-VSVG exosomes remained in the lungs for a long time. miR-486-RBD-MSC-exosomes significantly improved the survival rate and pathological changes in hACE2CKI/CKI Sftpc-Cre+ RIPF mice. Furthermore, miR-486-MSC-Exo exerted anti-fibrotic effects through targeted inhibition of SMAD2 and activation of Akt phosphorylation.Conclusions Here, miR-486-MSC-Exo inhibited lung injury and alleviated fibrosis in vivo and in vitro. Surface modification with COVID-S-RBD conferred engineered exosomes with the ability to target the lungs of animal models. The therapeutic effects of miR-486-5p and COVID-S-RBD-engineered MSC exosomes on RIPF were significantly enhanced. MSC-derived exosomes modified with recombinant COVID-S-RBD enabled targeted delivery of miR-486-5p, which is an effective approach for the treatment of RIPF.