Figure 8.

Cytotrophoblasts modulate VEGF receptor expression at the protein level as they differentiate in vitro. Cell lysates were prepared from first and second trimester cytotrophoblasts, either immediately after isolation (0 hours) or after they had been plated for 20 hours on Matrigel. Receptor expression was analyzed by immunoblotting. First and second trimester cells down-regulated expression of VEGFR-2 and up-regulated the expression of VEGFR-1. VEGFR-3 expression was higher in first trimester than in second. As a control, uterine vein endothelial cell (UtVEC) expression of the receptors was analyzed in parallel. Multiple bands may be due to receptor phosphorylation in some of the cytotrophoblast samples. Different glycoforms could also be present.