Uterine vascular remodeling and its clinical relevance during pregnancy

Angiogenesis is a critical process for reproduction in mammals consisting of arterioles and blood vessels formation from the existing vasculature. Human endometrium becomes highly vascularized during the secretory/luteal phase of menstrual cycle to prepare the uterus to receive the blastocyst during the implantation process. Future changes in uterine blood vessels are necessary, and among them the formation of the spiral arteries and the placental vascular bed are extremely important to support the development, growth and survival of the fetus in the womb. Moreover, microvasculature arteries perform the dynamic control of maternal blood flow to the placenta, a key process for healthy pregnancy. Deranged placental vasculature is the most common cause of gestational complications in placental mammals including preeclampsia, fetal growth restriction, preterm labor, placenta accreta and abortion. The process of vascular remodeling during pregnancy follows an orchestrated sequence of events involving trophoblast cells and maternal immune cells, which produce vasoactive substances such as VEGF, angiopoietin and PGF, as well as metalloproteinases and vasoactive gases. The biology of trophoblast cells and maternal immune system related to production of vasoactive substances and their role in vascular remodeling during pregnancy still a promising research field due to its importance on health and economics as well as because this process has not been fully elucidated.