TFPI and chronic obstructive pulmonary disease: Cella et al., compared the levels of nitric oxide (a powerful vasodilator and inhibitor of platelets aggregation), thrombomodulin (the endothelial surface site for binding and deactivating thrombin that subsequent activates protein C), and TFPI between patients with COPD and healthy controls, to evaluate the endothelial cell dysfunction associated with COPD.