Bone marrow-derived progenitor cells in end-stage lung disease patients

Background: Chronic lung diseases are marked by progressive inflammation, tissue damage and remodelling. Bone marrow-derived progenitor cells may contribute to these processes. The objectives of this study were to (1) to quantify CD45⁺Collagen-1⁺ fibrocytes and a novel epithelial-like population of bone marrow-derived cells, which express Clara Cell Secretory Protein, in patients at the time of lung transplant and (2) to evaluate mediators that may act to recruit these cells during injury.Methods: Using an observational design, progenitor cells were quantified by flow cytometry from both bone marrow (BM) and peripheral blood (PB). Migration was tested using in vitro transwell assays. Multiplex bead-based assays were used to quantify plasma cytokines.Results: An increase in CD45⁺Collagen-1⁺ fibrocytes was found in pulmonary fibrosis and bronchiolitis obliterans patients. Cystic fibrosis patients had an increase in CCSP⁺ cells in both the BM and PB. The proportion of CCSP⁺ cells in the BM and PB was correlated. CCSP⁺ cells express the chemokine receptors CCR2, CCR4, CXCR3, and CXCR4, and significantly migrated in vitro toward Stromal Derived Factor-1 (SDF-1) and Stem Cell Growth Factor-β (SCGF-β). Plasma cytokine levels differed between disease groups, with a significant correlation between SCGF-β and CCSP⁺ cells and between Monocyte Chemotactic Protein-1 and fibrocytes.Conclusions: Different bone marrow-derived cells are found in various lung diseases. Increased fibrocytes were associated with fibrotic lung diseases. An increase in the novel CCSP⁺ epithelial-like progenitors in cystic fibrosis patients was found. These differences may be mediated by alterations in plasma cytokines responsible for cell recruitment.