Nerve growth factor in human umbilical cord serum: demonstration of a veno-arterial gradient

An heterologous radioreceptor assay (RRA) for nerve growth factor (NGF) has been developed to measure NGF in human umbilical cord serum. The RRA uses mouse NGF (mNGF) as iodination material and as standard and a rat pheochromocytoma clonal line of cells (PC-12) as a source of NGF receptor (KD = 3.8 X 10(-9)M). Human cord serum exhibited parallel displacement of radiolabeled NGF in the RRA. Umbilical vein and artery NGF concentrations were measured in 22 healthy, full-term infants. The mean and (SEM) umbilical vein NGF concentration (30.4 +/- 3.2 pM/ml) significantly exceeded the mean umbilical artery NGF concentration (22.4 +/- 3.3 pM/ml) (p less than 0.05). Cord serum also produced a positive bioassay response (neurite outgrowth) in PC-12 cells, and this response was inhibited by anti-hNGF antiserum. These results are compatible with placental synthesis and secretion of NGF and suggest the possibility that NGF may play a role in autonomic and perhaps central nervous system maturation in the human fetus.