Increased tissue endothelial progenitor cells in end-stage lung diseases with pulmonary hypertension

Diffuse lung diseases promote the development of vascular changes and pulmonary hypertension (PH). Endothelial progenitor cells (EPCs) seem to be involved in pulmonary vascular remodeling. We evaluated circulating and intra-pulmonary EPCs in end-stage lung diseases in relation to pulmonary arterial pressure (PAP).

The study included 19 patients affected by different end-stage lung diseases, with or without PH. Six lung donors were considered as control group. EPCs were measured in blood samples taken at the time of transplant from pulmonary arteries and veins (by flow cytometry) as well as in lung specimen sections (by confocal microscopy) and expressed as percentage of total number of cells.

The amount of EPC in lung specimens was significantly different according to type of disease (p = 0.001). Specifically, a higher number of EPCs was detected in idiopathic pulmonary hypertension and idiopathic pulmonary fibrosis with high (> 25 mm Hg) mean PAP (p = 0.03 for both) compared with chronic obstructive pulmonary disease and control group. There was a direct correlation between intrapulmonary EPCs and PAP. According to receiver operating characteristic curve analysis, the presence of > 3% EPCs had a 91% sensitivity and 93% specificity in identifying high mean PAP. There were no differences in circulating arterial or venous EPCs among groups.

Intra-pulmonary EPCs are increased in lung diseases with high PAP, suggesting that EPCs may contribute to vascular remodeling in end-stage pulmonary disease.