Human Mesenchymal Stem Cell Microvesicles for Treatment of Escherichia coli Endotoxin-Induced Acute Lung Injury in Mice

Abstract

We previously found that human mesenchymal stem cells (MSC) or its conditioned medium restored lung protein permeability and reduced alveolar inflammation following E.coli endotoxin-induced acute lung injury (ALI) in an ex vivo perfused human lung in part through the secretion of soluble factors such as keratinocyte growth factor (KGF). Recently, MSC were found to release microvesicles (MV) that were biologically active because of the presence of mRNA or miRNA with reparative properties. MVs are circular fragments of membrane released from the endosomal compartment as exosomes or shed from the surface membranes. The current studies were designed to determine if MVs released by human bone marrow derived MSCs would be effective in restoring lung protein permeability and reducing inflammation in E.coli endotoxin-induced ALI in C57BL/6 mice. The intra-tracheal instillation of MVs improved several indices of ALI at 48 h. Compared to endotoxin-injured mice, MVs reduced extravascular lung water by 43% and reduced total protein levels in the bronchoalveolar lavage (BAL) fluid by 35%, demonstrating a reduction in pulmonary edema and lung protein permeability. MVs also reduced the influx of neutrophils and macrophage inflammatory protein-2 levels in the BAL fluid by 73% and 49% respectively, demonstrating a reduction in inflammation. KGF siRNA-pretreatment of MSC partially eliminated the therapeutic effects of MVs released by MSCs, suggesting that KGF protein expression was important for the underlying mechanism. In summary, human MSC derived microvesicles were therapeutically effective following E.coli endotoxin-induced ALI in mice in part through the expression of KGF mRNA in the injured alveolus.

Mesenchymal Stromal Cells Modulate Macrophages in Clinically Relevant Lung Injury Models by Extracellular Vesicle Mitochondrial Transfer

“…Additionally, the capacity of MSCs to induce polarization toward M2-type monocytes/macrophages, identified by CD206 expression, may serve as a biomarker for MSC efficacy in clinical samples. EVs have emerged as a major contributor to the therapeutic effects of MSCs in lung injury, capable of recapitulating many of the effects of the whole-cell therapy (25)(26)(27). CD44 expression on MSC-derived EVs was shown to be necessary for their uptake and therapeutic effect on target cells (27,50).…”

“…Recently, EVs have emerged as an important component of the MSC secretory repertoire. MSC-derived EVs may contain a diverse cargo, including proteins, mRNAs, microRNAs (miRNAs), and mitochondria, the functional effects of which remain largely unknown (9,(23)(24)(25). MSC-derived EVs alone are capable of recapitulating many of the beneficial effects of MSC whole-cell therapy (25)(26)(27)(28).…”

“…MSC-derived EVs may contain a diverse cargo, including proteins, mRNAs, microRNAs (miRNAs), and mitochondria, the functional effects of which remain largely unknown (9,(23)(24)(25). MSC-derived EVs alone are capable of recapitulating many of the beneficial effects of MSC whole-cell therapy (25)(26)(27)(28). Phinney and colleagues observed the transfer of MSC mitochondria and miRNAs via EVs to human macrophages in a model of silicosis and found that mitochondria enhanced macrophage bioenergetics, whereas miRNAs suppressed Toll-like receptor signaling (24).…”

Mesenchymal stem cells: mechanisms of potential therapeutic benefit in ARDS and sepsis

“…65 MSCs express high levels of genes essential to the regulation of haemopoietic stem cells, 66 stimulate proliferation of endogenous cardiac progenitor cells during experimental myocardial infarction, 67 and possibly increase the number of lung progenitor cells in response to injury. 65 Finally, MSCs seem able to aff ect tissue repair through the delivery of extracellular vesicles 68,69 and direct mitochondrial transfer. 70 Although a detailed exploration of this scientifi c literature is beyond the scope of this review, table 5 shows a brief overview of several representative studies.…”

“…Zhou et al 73 Renal capsule injection of exosomes isolated from human umbilical cord blood MSCs attenuated blood and histological markers of acute kidney injury in an in-vivo rat model; exosomes also limited apoptosis and oxidative stress in vitro Zhu et al 69 Intratracheal and intravenous delivery of microvesicles isolated from human MSCs reduced infl ammation and lung water in a murine lung injury model using Escherichia coli endotoxin; in-vitro microvesicles restored epithelial cell barrier function after infl ammatory injury…”