S-RBD-modified and miR-486-5p-engineered exosomes derived from mesenchymal stem cells alleviate radiation-induced lung injury and long-term pulmonary fibrosis via suppression of ferroptosis (preprint)

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.

Available Guidelines for Airlines-Responding to Communicable Diseases

The purpose of this study is to provide a quick reference for airline industry to examine their preparedness of an emergency response program (ERP) before a pandemic outbreak. The authors used Case Studies to review available documents and extract critical contents for airlines' reference. While many countries possess their own ERPs mainly focusing on aircraft mishaps or inflight emergencies, a specific review on pandemic threats affecting passengers should be addressed.