P regnancy-induced hypertension (PIH) complicates 6% to 10% of pregnancies.1 It represents 1 of the following 4 conditions: (1) pre-existing hypertension, (2) gestational hypertension and preeclampsia; (3) pre-existing hypertension plus superimposed gestational hypertension with proteinuria; and (4) unclassifiable hypertension. Among these conditions, preeclampsia entails severe consequences for both the mother and the fetus.
2,3During the first trimester of human pregnancy, the extravillous trophoblasts must migrate and invade the maternal decidua and differentiate to facilitate the uterine spiral arterioles to undergo transformation and widen their luminal diameter, thus supplying more blood containing oxygen and nutrients to the placenta and growing fetus. One of the major contributing factors to the development of PIH is the failure of the extravillous trophoblast invasion deep into the maternal decidua, Abstract-Pregnancy-induced hypertension diseases are classified as gestational hypertension, preeclampsia, or eclampsia. The mechanisms of their development and prediction are still to be discovered. Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is an angiogenic factor secreted by the placenta during the first trimester of human pregnancy that was shown to control trophoblast invasion, to be upregulated by hypoxia, and to be abnormally elevated in pathological pregnancies complicated with preeclampsia and intrauterine growth restriction. These findings suggested that sustaining EG-VEGF levels beyond the first trimester of pregnancy may contribute to pregnancy-induced hypertension. To test this hypothesis, osmotic minipumps delivering EG-VEGF were implanted subcutaneously into gravid OF1 (Oncins France 1) mice on day 11.5 post coitus, which is equivalent to the end of the first trimester of human pregnancy. Mice were euthanized at 15.5 and 18.5 days post coitus to assess (1) litter size, placental, and fetal weights; (2) placental histology and function; (3) maternal blood pressure; (4) renal histology and function; and (5) circulating soluble fms-like tyrosine kinase 1 and soluble endoglin. Increased EG-VEGF levels caused significant defects in placental organization and function. Both increased hypoxia and decreased trophoblast invasion were observed. Treated mice had elevated circulating soluble fms-like tyrosine kinase 1 and soluble endoglin and developed gestational hypertension with dysregulated maternal kidney function. EG-VEGF effect on the kidney function was secondary to its effects on the placenta as similarly treated male mice had normal kidney functions. Altogether, these data provide a strong evidence to confirm that sustained EG-VEGF beyond the first trimester of pregnancy contributes to the development of pregnancy-induced hypertension. (Hypertension. 2016;68:148-156.