The Dual Effect of Epidermal Growth Factor upon Human Chorionic Gonadotropin Secretion by the First Trimester Placenta in Vitro

Abstract

Epidermal growth factor (EGF) is believed to play an important role in the regulation of placental function. We have examined the effect of EGF upon first trimester (7-10 gestational weeks) placental hCG secretion and cellular differentiation using both static (explants and isolated cells) and kinetic (superfusion of explants) culture methods. In superfused explants, short (1-4 min) pulses of EGF increased both the rate and amplitude of spontaneous pulsatility of hCG. The frequency increased from 3/h to 5/h, and the amplitude increased compared to the control channels as calculated by the area under the curve. This effect was dose dependent and the concentration of 50 ng/ml, which was the lowest dose tested, was the most effective. In explants cultured for 24 h, EGF caused a 2-fold increase in hCG secretion, compared to control, P less than 0.05. In two different dispersed trophoblastic cell cultures, EGF added daily for the first week caused a 180% increase in hCG secretion, P less than 0.05. However, according to morphological criteria, i.e. light microscopy and vital staining, no significant effect upon the rate of differentiation to syncytiotrophoblast was observed in long-term cultures of one of these preparations. In conclusion, EGF plays a dual trophic role in stimulating hCG secretion in the first trimester. However, this effect is not dependent on cellular differentiation.