Angiogenic factors in placentas from pregnancies complicated by fetal growth restriction (Review)

The placenta is the organ that is responsible for providing the developing fetus with all the nutrients necessary for its growth and is also responsible for removing fetal waste. Placentation is a crucial process that includes angiogenesis. Angiogenesis involves not only the fetal circulation, but also placental and endometrial vascular changes. In this study, we review the literature regarding any impairment in the angiogenic process in placentas from pregnancies complicated by fetal growth restriction (FGR). Angiogenesis is regulated by a list of factors, also known as growth factors, such as the vascular endothelial growth factor (VEGF), the placental growth factor (PIGF) and the basic fibroblastic growth factor (bFGF), as well as the partial pressure of oxygen in the feto-placental vessels. Other factors, such as transcriptional factors, also play a pivotal role, controlling the above-mentioned growth factors. Alterations in these pathways have been described in cases of growth-restricted fetuses. In this review, we provide an insight into these processes and identify the most crucial factors involved.