Mesenchymal stem cell-derived extracellular vesicles improve the molecular phenotype of isolated rat lungs during ischemia/reperfusion injury

ABSTRACT BACKGROUND Lung ischemia/reperfusion (IR) injury contributes to development of severe complications in patients undergoing transplantation. Mesenchymal-stem-cells (MSCs)-derived Extracellular vesicles (EVs) exert beneficial actions comparable to those of MSCs without the risks of the cell-based strategy. The present research investigated EV-effects during IR injury in isolated rat lungs. METHODS An established model of 180 min-ex vivo lung perfusion (EVLP) was used. At 60 min EVs (N=5) or saline (N=5) were administered. Parallel experiments used labelled-EVs to determine EV biodistribution (N=4). Perfusate samples were collected to perform gas analysis and to assess concentration of nitric oxide, hyaluronan, inflammatory mediators, and leukocytes. Lung biopsies were taken at 180 min to evaluate hyaluronan, ATP, gene expression, and histology. RESULTS Compared to untreated lungs, EV-treated organs showed decreased vascular resistance and a rise of perfusate nitric oxide metabolites. EVs prevented the reduction in pulmonary ATP caused by IR. Increased medium-high-molecular-weight hyaluronan was detected in the perfusate and in the lung tissue of the IR+EV group. Significant differences in cell count on perfusate and tissue samples, together with induction of transcription and synthesis of chemokines, suggested EV-dependent modulation of leukocyte recruitment. EVs up-regulated genes involved in resolution of inflammation and oxidative stress. Biodistribution analysis showed that EVs were retained in the lung tissue and internalized within pulmonary cells. CONCLUSIONS This study shows multiple, novel EV influences on pulmonary energetics, tissue integrity, and gene expression during IR. The use of cell-free therapies during EVLP could constitute a valuable strategy for reconditioning and repair of injured lungs before transplantation.