Technical Notes: Serum Levels of Vascular Growth Factors During Pregnancy

The establishment of placental circulation during pregnancy represents one of the most striking examples of vasculogenesis and remodeling that occurs normally in the adult. Reduced placental vascular development and decreased uterine blood flow have been used as predictors of high-risk pregnancy, underscoring the importance of understanding the factors that regulate the formation of this vascular network. The vascular endothelial growth factor (VEGF) and angiopoietin (Ang) families are important regulators of these processes. VEGF family members, VEGF and placental growth factor (PlGF), and Ang family member, Ang-2, promote angiogenesis in many contexts including wound healing, cancer, and reproduction. Altered levels of both VEGF and PlGF have been observed in pregnancy complicated by pre-eclampsia, ectopic implantation, and small-for-gestational-age and Down's syndrome fetuses. Since Ang-2 is clearly involved in placental vascular development, it also seems likely to be involved in the etiology of these conditions. Examination of Ang-2 levels during abnormal pregnancy, as well as further investigation into the regulation of these angiogenic factors, may help further elucidate the specific role each plays during normal and high-risk pregnancy.

R&D Systems' Quantikine® ELISAs were used to precisely assay serum levels of VEGF (Catalog # DVE00), PlGF (Catalog # DPG00), and Ang-2 (Catalog # DANG20) during normal pregnancy.* Serum samples from first, second, and third trimester low-risk pregnancies and non-pregnant controls were obtained by informed consent and assayed for concentrations of VEGF, PlGF, and Ang-2. VEGF concentrations were high in non-pregnant controls but decreased to undetectable levels early in the first trimester. Serum concentrations of both PlGF and Ang-2 increased during the first trimester and were maintained at levels higher than controls throughout gestation.

*Levels of soluble VEGF, PlGF, and Ang-2 receptors, sVEGF R1, sVEGF R2, and sTie-2 respectively, were also measured using R&D Systems' Quantikine® ELISAs.