Integrin α6β4 Identifies Human Distal Lung Epithelial Progenitor Cells with Potential as a Cell-Based Therapy for Cystic Fibrosis Lung Disease

Xiaopeng Li,Andrew L Hornick,Philip H Karp,Sarah E Ernst,Ryan J Adam,Dana N Levasseur,Thomas O Moninger,Joseph Zabner,Benjamin R Steines,Nathan Rossen,Patrick L Sinn,Shama Ahmad

doi:10.1371/journal.pone.0083624

Abstract

To develop stem/progenitor cell-based therapy for cystic fibrosis (CF) lung disease, it is first necessary to identify markers of human lung epithelial progenitor/stem cells and to better understand the potential for differentiation into distinct lineages. Here we investigated integrin α6β4 as an epithelial progenitor cell marker in the human distal lung. We identified a subpopulation of α6β4+ cells that localized in distal small airways and alveolar walls and were devoid of pro-surfactant protein C expression. The α6β4+ epithelial cells demonstrated key properties of stem cells ex vivo as compared to α6β4- epithelial cells, including higher colony forming efficiency, expression of stem cell-specific transcription factor Nanog, and the potential to differentiate into multiple distinct lineages including basal and Clara cells. Co-culture of α6β4+ epithelial cells with endothelial cells enhanced proliferation. We identified a subset of adeno-associated virus (AAVs) serotypes, AAV2 and AAV8, capable of transducing α6β4+ cells. In addition, reconstitution of bronchi epithelial cells from CF patients with only 5% normal α6β4+ epithelial cells significantly rescued defects in Cl- transport. Therefore, targeting the α6β4+ epithelial population via either gene delivery or progenitor cell-based reconstitution represents a potential new strategy to treat CF lung disease.

Highlights

Cystic fibrosis (CF), which is caused by loss of cystic fibrosis transmembrane conductance regulator (CFTR), affects multiple organs, though lung disease is the main cause of morbidity and mortality in patients with CF [1]
Isolation and localization of human distal lung epithelial progenitor cells Given that the data regarding the presence of a multipotent lung epithelial progenitor cell population are conflicting [3,4], our objective in this study was to investigate whether multipotent progenitor cells are present in human distal lungs
To realize the full potential of stem cell therapy for diseases such as CF, it is necessary to determine biomarkers that identify progenitor cells in distinct regions of the lung and to understand the potential of these progenitor cells to differentiate into different epithelial cell lineages

Summary

Introduction

Cystic fibrosis (CF), which is caused by loss of cystic fibrosis transmembrane conductance regulator (CFTR), affects multiple organs, though lung disease is the main cause of morbidity and mortality in patients with CF [1]. The long-term vision is to use stem cellbased therapy to regenerate the defective epithelia and thereby reverse the physiological and pathological abnormalities caused by the loss of CFTR. These approaches are still in their infancy and require extensive research, including a better understanding of the processes by which stem cells transition to progenitor cells and eventually become differentiated lung epithelial cells. Lineage tracing studies targeting known markers for putative adult lung multipotent stem/progenitor cells have failed to identify such a population under non-pathological conditions in mice [5]. In order to develop epithelial progenitor cell-based therapy for CF, it is first necessary to understand if multipotent epithelial progenitor cells exist or if different regions of the lung contain distinct populations of progenitor cells with limited differentiation potential [9,10]

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Conclusion