Angiopoietin/tie receptors system may play a role during reconstruction and capillarization of the hepatic sinusoids after partial hepatectomy and liver necrosis in rats.

Abstract

Sinusoidal endothelial cells and hepatocytes increase in number after partial resection and necrosis of the liver, and contribute to both reconstruction and capillarization of the sinusoids through interaction with stellate cells. The mechanism underlying such interaction was evaluated regarding angiopoietins and tie receptors essential for blood vessel formation. Hepatic mRNA expressions of angiopoietin-1, angiopoietin-2 and tie-2 were increased at 168h after 70% liver resection with sinusoidal reconstruction in rats, and also at 48h with sinusoidal capillarization in the liver of rats given carbon tetrachloride (CCl(4)). Tie-2 mRNA expression was detected in sinusoidal endothelial cells and stellate cells isolated from normal rats, and in activated stellate cells from CCl(4)-intoxicated rats. The mRNA expressions of angiopoietin-1 and angiopoietin-2 were detectable in Kupffer cells, sinusoidal endothelial cells and stellate cells in normal rats, but increased in activated stellate cells and macrophages after CCl(4)-intoxication. Both angiopoietins and tie-2 were immunohistochemically stained along the sinusoids of 70% hepatectomized rats and in necrotic areas of CCl(4)-intoxicated rats. Angiopoietin-1 and angiopoietin-2 may be involved in both reconstruction and capillarization of the sinusoids in rat liver after partial resection and necrosis through interaction between stellate cells and sinusoidal and vascular endothelial cells via tie-2 receptor.