Angiogenesis and disruption of liver vascular architecture have been linked to progression to cirrhosis and liver cancer (HCC) in chronic liver diseases, which contributes both to increased hepatic vascular resistance and portal hypertension and to decreased hepatocyte perfusion. On the other hand, recent evidence shows that angiogenesis modulates the formation of portal-systemic collaterals and the increased splanchnic blood flow which are involved in the life threatening complications of cirrhosis. Finally, angiogenesis plays a key role in the growth of tumours, suggesting that interference with angiogenesis may prevent or delay the development of HCC. This review summarizes current knowledge on the molecular mechanisms of liver angiogenesis and on the consequences of angiogenesis in chronic liver disease. On the other hand, it presents the different strategies that have been used in experimental models to counteract excessive angiogenesis and its potential role in preventing transition to cirrhosis, development of portal hypertension and its consequences, and its application in the treatment of hepatocellular carcinoma.

Portal hypertension, the most important complication in patients with cirrhosis of the liver, is a serious and life-threatening disease for which there are few therapeutic options. Because angiogenesis is a pathological hallmark of portal hypertension, the goal of this study was to determine the effects of sorafenib-a potent inhibitor of proangiogenic vascular endothelial growth factor receptor 2 (VEGFR-2), platelet-derived growth factor receptor ␤ (PDGFR-␤), and Raf kinases-on splanchnic, intrahepatic, systemic, and portosystemic collateral circulations in two different experimental models of portal hypertension: rats with prehepatic portal hypertension induced by partial portal vein ligation and rats with intrahepatic portal hypertension and secondary biliary cirrhosis induced by bile duct ligation. Such a comprehensive approach is necessary for any translational research directed toward defining the efficacy and potential clinical application of new therapeutic agents. Sorafenib administered orally once a day for 2 weeks in experimental models of portal hypertension and cirrhosis effectively inhibited VEGF, PDGF, and Raf signaling pathways, and produced several protective effects by inducing an approximately 80% decrease in splanchnic neovascularization and a marked attenuation of hyperdynamic splanchnic and systemic circulations, as well as a significant 18% decrease in the extent of portosystemic collaterals. In cirrhotic rats, sorafenib treatment also resulted in a 25% reduction in portal pressure, as well as a remarkable improvement in liver damage and intrahepatic fibrosis, inflammation, and angiogenesis. Notably, beneficial effects of sorafenib against tissue damage and inflammation were also observed in splanchnic organs. Conclusion: Taking into account the limitations of translating animal study results into humans, we believe that our findings will stimulate consideration of sorafenib as an effective therapeutic agent in patients suffering from advanced portal hypertension. (HEPATOLOGY 2009;49:1245-1256 See Editorial on Page 1066 P ortal hypertension is the most important complication that develops in patients with cirrhosis of the liver and remains a leading cause of morbidity and mortality worldwide. 1 The portal hypertensive syndrome is characterized by a pathological increase in portal pressure and by the development of hyperdynamic splanchnic circulation, with an increase in blood flow in splanchnic organs draining into the portal vein and a subsequent elevation in portal venous inflow. Such increased portal venous inflow is a significant factor maintaining and worsening portal pressure elevation and determining the formation of ascites. Another characteristic feature of portal hypertension is the formation of an extensive network of portosystemic collateral vessels; these include gastroesophageal varices, which are prone to rupture that can cause massive, life-threatening gastroesophageal bleeding. In addition, collateral vessels result in shunting of portal blood into the systemic circulation ...

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