Angiopoietin-1 is an apoptosis survival factor for endothelial cells

We examined the effect of angiopoietin-1 (Ang1) on apoptosis in human umbil ical vein endothelial cells (HUVECs). Ang1 (5-1000 ng/ml) dose-dependently inhibited apoptosis under a serum-deprived state. A significant apoptotic i nhibition occurred with as low as 50 ng/ml. Two hundred ng/ml of Ang1 inhib ited to approximately 50% of the control apoptotic rates for 96 h. Furtherm ore, an augmented antiapoptotic effect of Ang1 by the addition of 20 ng/ml vascular endothelial growth factor was observed. This Ang1-iuduced strong a ntiapoptotic effect in endothelial cells is a novel and intriguing finding and could be an additional description of Ang1-induced direct biological fu nction. (C) 1999 Federation of European Biochemical Societies.