Abstract
Bone marrow-derived progenitor cells have been shown to participate in angiogenesis, vascular repair and tissue remodelling in pulmonary arterial hypertension (PAH). A unique subpopulation of peripheral blood mononuclear cells (PBMC), termed fibrocytes, has been demonstrated to develop myofibroblasic phenotype and contribute to the vascular remodelling process in hypoxic models of PAH. To extend these studies, we tested the hypothesis that circulating fibrocytes contribute to human PAH and examined their possible role as predictors of activity and progression of disease.
18 patients with idiopathic and familial PAH and 20 healthy control subjects were studied. Circulating fibrocytes, identified as CD11b+CD34+vimentin+ cells and membrane CD11b expression were quantified by flow cytometry. The in vitro differentiation capacity of PBMC to fibrocytes was quantified.
We observed a slight decrease in the percentage but not in the number of circulating fibrocytes in the blood of PAH patients, compared with healthy control subjects (0.67±0.015% in control subjects vs 0.22±0.04% in PAH patients, p<0.05). Accordingly, a significant decrease in the percentage of differentiated CD45+vimentin+ cells in PBMC culture from PAH patients was observed (73±3% in control group vs 61±2% in PAH patients, p<0.05). Interestingly, the mean fluorescence intensity of CD11b was significantly increased on circulating fibrocytes in PAH patients (1112±116 in control group vs 2167±247 in PAH patients, p<0.0001), indicating their increased activation state.
Our data suggest that a more detailed analysis of circulating fibrocyte function and activation is needed in PAH patients.
- © 2011 ERS
