Mesenchymal stromal cell extracellular vesicles rescue mitochondrial dysfunction and improve barrier integrity in clinically relevant models of ARDS.

Johnatas Dutra Silva,Carolyn S Calfee,Danny F Mcauley,Kevin L Delucchi,Daniel Weiss,Yue Su,Cecilia O'Kane,Anna D Krasnodembskaya

doi:10.1183/13993003.02978-2020

Abstract

Alveolar epithelial–capillary barrier disruption is a hallmark of acute respiratory distress syndrome (ARDS). Contribution of mitochondrial dysfunction to the compromised alveolar-capillary barrier in ARDS remains unclear. Mesenchymal stromal cells-derived extracellular vesicles (MSC-EVs) are considered as a cell-free therapy for ARDS. Mitochondrial transfer was shown to be important for the therapeutic effects of MSCs and MSC-EVs. Here we investigated the contribution of mitochondrial dysfunction to the injury of alveolar epithelial and endothelial barriers in ARDS and the ability of MSC-EVs to modulate alveolar–capillary barrier integrity through mitochondrial transfer.Primary human small airway epithelial and pulmonary microvascular endothelial cells and human precision cut lung slices (PCLSs) were stimulated with endotoxin or plasma samples from patients with ARDS and treated with MSC-EVs, barrier properties and mitochondrial functions were evaluated. Lipopolysaccharide (LPS)-injured mice were treated with MSC-EVs and degree of lung injury and mitochondrial respiration of the lung tissue were assessed.Inflammatory stimulation resulted in increased permeability coupled with pronounced mitochondrial dysfunction in both types of primary cells and PCLSs. Extracellular vesicles derived from normal MSCs restored barrier integrity and normal levels of oxidative phosphorylation while an extracellular vesicles preparation which did not contain mitochondria was not effective. In vivo, presence of mitochondria was critical for extracellular vesicles ability to reduce lung injury and restore mitochondrial respiration in the lung tissue.In the ARDS environment, MSC-EVs improve alveolar–capillary barrier properties through restoration of mitochondrial functions at least partially via mitochondrial transfer.

Highlights

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterised by widespread uncontrolled inflammation in the lungs
We explored the contribution of mitochondrial dysfunction to the injury of alveolar epithelial and endothelial barriers in ARDS and the ability of Mesenchymal stromal cells-derived extracellular vesicles (MSC-extracellular vesicles (EVs)) to modulate alveolar-capillary barrier functions through mitochondrial transfer
To generate Mesenchymal stromal cells (MSCs) with dysfunctional mitochondria, MSCs were treated with 1 μg·mL−1 Rhodamine-6G (Sigma-Aldrich) for 48 h [20] in medium supplemented with 50 ug·mL−1 uridine and 2.5 mM sodium pyruvate (Sigma-Aldrich) to support glycolysis, washed with PBS and incubated for 48 h in serum free medium. extracellular vesicles were isolated from conditioned medium (Rho-EVs) and handled identically to extracellular vesicles isolated from normal MSCs

Summary

Introduction

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterised by widespread uncontrolled inflammation in the lungs. Two biological phenotypes have been identified retrospectively in four randomised clinical trials [5,6,7] and one observational study [8]. These phenotypes had different clinical characteristics, biomarker profiles, clinical outcomes and, more importantly, they responded differently to interventions (positive end-expiratory pressure, fluid management strategy, low-dose macrolide therapy and simvastatin administration). The field is still waiting for the confirmation of these findings in prospective studies, when developing novel therapeutics, it will be important to consider which ARDS phenotype is present and how it may respond

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Results

Conclusion