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Many lung-transplanted (LTx) patients develop obliterative bronchiolitis (OB) with deposition of extracellular matrix, accompanied by fibrocyte infiltration and increased lumen of vessels. In this study we hypothesize that fibrocytes, VEGF and prostacyclin (PGI2) are involved in remodelling processes after LTx. We investigated TGF-β activated peripheral fibroblast phenotypes regarding production of VEGF 165 /PGI2. Fibrocytes and fibroblast phenotypes were identified by prolyl4-hydroxylase (p4OH), CD45, VEGFR2 or PGIR. VEGF production from fibroblasts after LTx significantly decreased 3mo after LTx compared to healthy controls (p

Background: The mesenchymal stromal cells (MSC) are potent candidates for cell therapies, due to their immune-regulatory and regenerative properties. In most clinical trials bone marrow-derived MSC have been used, also for treatment of various pulmonary diseases. Bone marrow-derived MSC play an important role within the bone marrow, by providing and maintaining a functioning niche for the hematopoiesis. The functional role of lung-resident MSC, on the other hand, is still unknown. Exploring the proteins produced by lung-derived MSC might improve our understanding of the functional role of MSC within the lung. Therefore, we aimed to characterize the proteins produced by lung-derived MSC and to compare those findings to the proteins produced by MSC isolated from bone marrow. Methods: Proteins within the cell-layer and the conditioned medium of MSC isolated from lung biopsies and bone marrow aspirates were characterized using mass spectrometry-based quantitative proteomics. Results: Our results indicate that MSC isolated from lung biopsies and bone marrow aspirates are prominent producers of extracellular matrix proteins. Furthermore, these analyses revealed differences between lung- and bone marrow-derived MSC, both regarding proteins identified in the cell layer and within the conditioned medium. Conclusions: Lung-derived MSC are prominent extracellular matrix producers, and our results indicate that lung- and bone marrow-derived MSC produce different protein profiles.

Rationale: Idiopathic pulmonary fibrosis (IPF) is characterized by loss of lung function due to aberrant deposition of extracellular matrix (ECM) constituents. One such constituent is glycosaminoglycans (GAGs) consisting of unbranched polymers of repeating disaccharides. They are highly negatively charged which renders them the ability to interact with important mediators in the IPF pathogenesis. The abundance and localisation of GAGs in relation to tissue density is not known in IPF. The aim of this study was therefore to measure GAGs in lung samples from IPF patients and from control subjects. Methods: Lung tissue samples were collected from more or less dense areas in distal lungs from IPF patients (n=8) and from donor lungs (n=4). GAGs were isolated and quantified by HPLC after fluorochrome labelling. The total collagen content was quantified by the amount of hydroxyproline and fibrillar collagen was measured by picro-sirius red staining. Results: The total amount of heparan sulfate (HS), chondroitin/dermatan sulfate (CS/DS) and hyaluronan (HA) was significantly higher in denser areas of IPF lungs compared to less dense areas (p ≤ 0.01 for HS, p ≤ 0.05 for CS/DS and p ≤ 0.01 for HA) and also compared to control lungs. HA was significantly increased in less fibrotic areas compared to control lungs. Moreover, the amount of GAGs in IPF tissue correlated with the volume fraction of picro-sirius red stain but not with the hydroxyproline content. Conclusions: Our results show that GAGs are quantatively elevated in fibrotic lesions characterized by high tissue density and increased levels of fibrillar collagen in IPF. This may create an altered ECM niche that promotes an active remodelling process.