Circulating endothelial progenitor cells and chronic pulmonary diseases

Circulating endothelial progenitor cells (EPCs) are bone marrow-derived cells that contribute to vascular healing and remodelling under physiological and pathological conditions. Although controversies exist regarding the definition and origin of EPCs, it has been widely demonstrated that they are involved in several diseases and that they have therapeutic implications. Chronic obstructive pulmonary disease (COPD) is characterised by airflow limitation that is not fully reversible, associated with abnormalities of airways (bronchitis) and parenchyma (emphysema), reduced exercise tolerance and systemic inflammation. Growing evidence has also suggested that endothelial dysfunction may play a role in COPD. Although it is not clear whether endothelial dysfunction represents a cause or a consequence of COPD, several studies have highlighted the importance of EPCs in this disease, suggesting that the bone marrow could be a novel target of COPD. The present review summarises the role of EPCs in pulmonary diseases, with particular emphasis on COPD. The aim is to improve understanding as to the possible role of EPCs in COPD pathophysiology. This may help in the identification of novel diagnostic and therapeutic tools in COPD.