Role of the angiopoietin/Tie system in pregnancy (Review)

Angiopoietin-1 and -2 are endogenous ligands for the vascular endothelium-specific receptor tyrosine kinase Tie-2. The angiopoietin/Tie system plays a critical role in the regulation of endothelial cell survival and vascular maturation and stability. Apart from its well-established role in vascular morphogenesis, emerging data support the involvement of angiopoietins in inflammation and various malignancies. Previous studies have underlined the significance of several angiogenic factors in normal placental development. In addition, angiogenic imbalance is observed in pregnancy complications related to impaired placentation, such as preeclampsia (PE) and intrauterine growth restriction (IUGR). However, there is only limited information available on the role of the angiopoietin/Tie system in the establishment of a competent feto-maternal vascular system. In this review, we present the current knowledge regarding the role of angiopoietins in normal pregnancy and pregnancy complications.