The pathobiology of pulmonary hypertension - Endothelium

Mild to moderate pulmonary hypertension (PH) is characterized histologicall y by medial smooth muscle cell hypertrophy. Sever PH (primary and secondary ) is characterized by the presence of intraluminal clusters of endothelial cells in pulmonary arteries. We review the evolving concepts of pulmonary e ndothelial cell dysfunction in severe PH. Our most recent findings indicate that mutations underlie the endothelial cell proliferation seen in PPH, su ggesting that endothelial progenitor-like cells may be activated to grow an d eventually disrupt pulmonary artery flow.