Objective: The purpose of the study was to determine the angiogenic capacity of sera in early and late pregnancy and in umbilical blood serum after childbirth, and to define how angiogenic properties assessed in a functional in vitro test are related to individual angiogenic proteins in six women with pre-eclampsia and in six healthy pregnant controls.
Methods: Maternal first and third trimester serum samples, and umbilical blood samples after childbirth, were tested in an in vitro human adipose stromal cell-human umbilical vein endothelial cell (hASC-HUVEC) vasculogenesis/angiogenesis assay. The angiogenic properties of the samples were measured by quantifying tubule formation. Concentrations of total placental growth factor (PlGF), total vascular endothelial growth factor (VEGF), soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEng) were determined by immunoassay.
Results: First-trimester maternal sera of both groups had a stimulatory effect on angiogenesis in vitro and levels of angiogenic proteins did not differ between the groups. Third-trimester maternal sera in the pre-eclampsia group had an inhibitory effect on tubule formation, while those from normal pregnancies remained stimulatory. Compared with the first trimester there was a significant change in the concentrations of angiogenic proteins toward an anti-angiogenic state in pre-eclampsia. Umbilical blood serum exhibited strong anti-angiogenic effects without a significant difference between groups.
Conclusions: Third-trimester serum of pre-eclamptic patients is anti-angiogenic. This phenomenon is not yet present in the first trimester. Umbilical blood serum shows inhibitory effects on angiogenesis after normal as well as pre-eclamptic pregnancy.
Keywords: Angiogenic proteins; In vitro vasculogenesis/angiogenesis; Inhibition of angiogenesis; PlGF; Pre-eclampsia; VEGF; sEng; sFlt-1.