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Portal hypertension (PHT) is a heterogeneous clinical entity which develops in patients with cirrhosis. It is responsible for many of the complications that occur in cirrhosis, including gastroesophageal varices, hepatorenal syndrome, ascites, hepatic encephalopathy and hypersplenism.1 There are three principal factors responsible for the development of PHT, namely (1) purely mechanical obstruction resulting from hepatic fibrosis and regenerative nodules; (2) contraction of sinusoidal and perisinusoidal contractile cells due to an imbalance between intrahepatic vasoconstrictory and vasodilatory mediators and (3) splanchnic vasodilation and increased portal blood flow.1 Factors leading to the development of PHT include hypoxia, oxidative stress, inflammation and shear stress as potential mediators for the angiogenic response. Vascular Endothelial Growth factor (VEGF) is a key mediator in regulating the angiogenic switch in many pathological conditions, and is also probably a major player in the neoangiogenic process during the development of a hyperdynamic splanchnic circulation, and the formation of portal-systemic collateral vessels.2 This has led to many studies seeking to identify signalling pathways that interact with, or affect the formation and action of VEGF switching.
Mejias reports in this issue3 a new mechanism and therapeutic effect by targeting endogenous pigment epithelium-derived factor (PEDF) in bile duct-ligated portal hypertensive rats. PEDF belongs to the subgroup of the so-called non-inhibitory serpins that lack the protease inhibitory activity …