Allogeneic Human Mesenchymal Stem Cells Restore Epithelial Protein Permeability in Cultured Human Alveolar Type II Cells by Secretion of Angiopoietin-1*♦

Xiaohui Fang,Arne P Neyrinck,Michael A Matthay,Jae W Lee

doi:10.1074/jbc.m110.119917

Abstract

Acute lung injury is characterized by injury to the lung epithelium that leads to impaired resolution of pulmonary edema and also facilitates accumulation of protein-rich edema fluid and inflammatory cells in the distal airspaces of the lung. Recent in vivo and in vitro studies suggest that mesenchymal stem cells (MSC) may have therapeutic value for the treatment of acute lung injury. Here we tested the ability of human allogeneic mesenchymal stem cells to restore epithelial permeability to protein across primary cultures of polarized human alveolar epithelial type II cells after an inflammatory insult. Alveolar epithelial type II cells were grown on a Transwell plate with an air-liquid interface and injured by cytomix, a combination of IL-1β, TNFα, and IFNγ. Protein permeability measured by 131I-labeled albumin flux was increased by 5-fold over 24 h after cytokine-induced injury. Co-culture of human MSC restored type II cell epithelial permeability to protein to control levels. Using siRNA knockdown of potential paracrine soluble factors, we found that angiopoietin-1 secretion was responsible for this beneficial effect in part by preventing actin stress fiber formation and claudin 18 disorganization through suppression of NFκB activity. This study provides novel evidence for a beneficial effect of MSC on alveolar epithelial permeability to protein.

Highlights

ALI/ARDS is initiated by direct lung injury or systemic inflammatory processes
In an ex vivo perfused human lung preparation, we found that the intrabronchial instillation of mesenchymal stem cells (MSC) after E. coli endotoxin-induced lung injury restored alveolar fluid clearance in part through secretion of keratinocyte growth factor, which increased sodium and vectorial fluid transport across the alveolar epithelium [27]
Human Mesenchymal Stem Cells Restore Protein Permeability Across Human ATII Cells Injured by Cytomix—Protein permeability increased across primary cultures of human alveolar epithelial type II cells exposed to cytomix (1.9 Ϯ 1 versus 10.7 Ϯ 5%/24 h for control and cytomix-injured ATII cells, respectively) (Fig. 2)

Summary

Introduction

ALI/ARDS is initiated by direct lung injury or systemic inflammatory processes. Diffuse alveolar damage is the hallmark of the acute phase of ALI/ARDS with increased permeability of the capillary endothelium and alveolar epithelium. To investigate the role of Ang1 secretion by MSC on protein permeability, we exposed primary cultures of human ATII cells to cytomix and added MSC in the lower compartment of the Transwell system pretreated with or without Ang1 siRNA.

Results

Conclusion