Endothelial progenitors in pulmonary hypertension: new pathophysiology and therapeutic implications

Pulmonary hypertension is a progressive and disabling disease with as yet unclear pathogenesis, limited treatment options and poor prognosis. This is why the discovery of new pathogenic mechanisms and therapeutic strategies are needed. Endothelial progenitor cells (EPCs) are bone marrow-derived cells involved in endothelial homeostasis, as well as physiological and pathological angiogenesis. Experimental and clinical studies have been conducted to understand the possible contribution of EPCs to the pathogenesis of pulmonary hypertension. Conflicting results have been obtained regarding the protective versus harmful effects of EPCs on the pulmonary vasculature. However, preliminary clinical trials using EPC-based therapies in patients with pulmonary hypertension show benefit of this approach, thus revealing EPCs as potential therapeutic targets. This review critically summarises the complex and conflicting data on EPCs and pulmonary hypertension, in both humans and animals, putting them into the context of lung (patho)physiology. The resulting scenario identifies EPCs as a novel and fascinating tool to study pathophysiology and therapy in the setting of pulmonary hypertension.