Studies of Placental Vasculogenesis: a Way to Understand Pregnancy Pathology?

Abstract

Undisturbed development and growth of the fetus depends on an adequate vascular development in the fetomaternal unit. Several steps of vascular adaptation both on fetal and maternal side are necessary and involve uterine vasodilation and remodelling by extravillous trophoblast as well as vasculo- and angiogenesis within the placenta. Ubiquitous (e. g. VEGF, bFGF) as well as pregnancy specific (PlGF, hCG, IGF-II, AFP) angiogenic factors are involved. Consequences of abnormal vascular development have been associated with different pregnancy-related pathologies ranging from miscarriage to intrauterine growth restriction or preeclampsia. Pregnancy-associated exposure to bacterial and viral infections or toxic agents (e. g. alcohol, nicotine or drugs) may also influence vascular development of the placenta and often lead to preterm labour and delivery. Different methods of study placental vascular development exist. Morphological and stereological approaches as well as animal models reveal significant limitations and can not be applied to in vivo human situation without hesitation. There is a need to design in vitro models of human placental vascular development allowing studies into the different aspects of this process including: trophoblast and stromal cells, interaction with endothelial progenitor cells, influence of viral or bacterial infection of trophoblast as well as influence of toxic agents. Our manuscript reviews major aspects of vascular development in the placenta and describes author's efforts to establish a three-dimensional model of this process in vitro.