Angiopoietin‐1 is an apoptosis survival factor for endothelial cells

We examined the effect of angiopoietin‐1 (Ang1) on apoptosis in human umbilical vein endothelial cells (HUVECs). Ang1 (5–1000 ng/ml) dose‐dependently inhibited apoptosis under a serum‐deprived state. A significant apoptotic inhibition occurred with as low as 50 ng/ml. Two hundred ng/ml of Ang1 inhibited to approximately 50% of the control apoptotic rates for 96 h. Furthermore, an augmented antiapoptotic effect of Ang1 by the addition of 20 ng/ml vascular endothelial growth factor was observed. This Ang1‐induced strong antiapoptotic effect in endothelial cells is a novel and intriguing finding and could be an additional description of Ang1‐induced direct biological function.