Abstract
Background: Pulmonary fibrosis (PF) is a progressive disease of unknown etiology. Abnormal alveolar epithelial wound repair after injury may result in pulmonary fibrosis. We hypothesize that stem cells have a healing capacity by migrating to the site of injury and secreting hepatocyte growth factor (HGF) which supports alveolar epithelial repair, therefore contributing in reduction of fibrosis.
Methods: Immunohistochemistry using paraffin lung sections from patients with two histological lung fibrosis pattern, usual interstitial pneumonia (UIP) and non-specific interstitial pneumonia (NSIP) (both n=5) was performed with several stem cell markers.
Results: Specific cells in the lung parenchyma were stained positive for HGF in UIP and NSIP. They were mainly located in the fibrotic areas. These HGF-positive cells did not co-stain for markers of alveolar epithelial cell (Surfactant protein C) or fibroblasts (vimentin). However, HGF-positive cells showed strong co-staining for the mesenchymal stem cell markers CD44, CD29, CD105, and CD90, indicating that HGF positive cells in the lung are of stem cell origin. The HGF-positive cells were also positive for CXCR4, suggesting that the HGF-positive cells in UIP and NSIP are recruited from the bone marrow.
Conclusion: HGF-positive stem cells with the origin of the bone marrow (CXCR4 positive) can be detected in both UIP and NSIP, indicating a crucial role in the development or resolution of pulmonary fibrosis. These data indicate a possible role for stem cell therapy of patient with fibrotic lung disease in the future.
- © 2011 ERS