Vascular endothelial growth factor is bound in amniotic fluid and maternalserum

To study vascular endothelial growth factor (VEGF) and placenta growth fact or (PlGF) concentrations and their possible binders, serum from 22 non-preg nant and 55 pregnant women (15 at weeks 10-13; 40 at term), umbilical vein (n = 24) and artery (n = 13) and amniotic fluid (a pool of 50 at weeks 15-1 7; 11 at term) were assessed for VEGF and PlGF by an enzyme-linked immunoso rbent assay. In amniotic fluid and maternal serum VEGF concentrations were <16 ng/ml and added VEGF was not recovered. VEGF was detected in serum from mothers postpartum (137 +/- 142 ng/l, mean +/- SD), umbilical artery (421 +/- 288 ng/l) and vein (502 +/- 339 ng/l) and nonpregnant controls (182 +/- 147 ng/l), and added VEGF was fully recovered. PlGF was detected in pregna ncy serum (52 +/- 23 ng/l early pregnancy; 439 +/- 217 ng/l term pregnancy) and in amniotic fluid (early pregnancy 56 ng/l; term pregnancy 30 +/- 18 n g/l). PlGF was fully recovered in all samples. Gel filtration and isoelectr ic focusing revealed that in maternal serum and amniotic fluid [I-125]VEGF was bound to a protein with an M-r of 400-700 kDa and an isoelectric point of approximately 8. This protein was not identical with alpha-2-macroglobul in (by an immunofluorometric assay), pregnancy zone protein or pregnancy as sociated plasma protein-A (by immunodiffusion). In conclusion, VEGF-binding activity is present in amniotic fluid and maternal blood. It disappears af ter delivery and is not detectable in fetal or non-pregnant serum.