Apoptosis in human cultured trophoblasts is enhanced by hypoxia and diminished by epidermal growth factor

Preeclampsia and fetal growth restriction are associated with placental hyp operfusion and villous hypoxia. The villous response to this environment in cludes diminished trophoblast differentiation and enhanced apoptosis. We te sted the hypothesis that hypoxia induces apoptosis in cultured trophoblasts , and that epidermal growth factor (EGF), an enhancer of trophoblast differ entiation, diminishes hypoxia-induced apoptosis. Trophoblasts isolated from placentas of term-uncomplicated human pregnancies were cultured up to 72 h in standard (Po-2 = 120 mmHg) or hypoxic (Po-2 < 15 mmHg) conditions. Expo sure to hypoxia for 24 h markedly enhanced trophoblast apoptosis as determi ned by DNA laddering, internucleosomal in situ DNA fragmentation, and histo morphology, as well as by the reversibility of the apoptotic process with a caspase inhibitor. Apoptosis was accompanied by increased expression of p5 3 and Bar and decreased expression of Bcl-2. Addition of EGF to cultured tr ophoblasts or exposure of more differentiated trophoblasts to hypoxia signi ficantly lowered the level of apoptosis. We conclude that hypoxia enhances apoptosis in cultured trophoblasts by a mechanism that involves an increase in p53 and Bar expression. EGF and enhancement of cell differentiation pro tect against hypoxic-induced apoptosis.