Trophoblast proliferation is higher in female than in male preeclamptic placentas

Preeclampsia (PE) is a pregnancy-specific hypertensive disorder with inflammatory complications. There are no known placental histopathological features, which are unique to PE. It is often pooled with the fetal growth restriction (FGR) under a single umbrella pathophysiology, the maternal vascular malperfusion (MVM). The aim of this study is to assess the villous trophoblast and the villous tree quantitatively in PE placentas and to identify morpholgical correlates unique to PE.

20 PE placentas (10 female and 10 male) and 20 Control placentas (10 female and 10 male) were included in the study. The villous trophoblast and the villous tree were assessed quantitatively by Stereology and 3D Microscopy. For Stereology measurements, the villous tree was classified in contractile and non-contractile parts based on immunohistochemical detection of perivascular myofibroblasts.

The density of proliferative trophoblast nuclei is increased, whereas the density of non-proliferative trophoblast nuclei is decreased in female PE placentas. The male PE placentas do not show this effect. Though no significant difference in the diffusion distance was observed, the non-contractile villi and the fetal vessels inside show a significantly reduced volume in PE placentas. The branching index of the villous tree is lower in PE placentas in general. However, in female PE placentas the deviation is accentuated.

In PE, the villous trophoblast shows a sexually dimorphic alteration in the density of proliferative and non-proliferative nuclei, which is inherently different from FGR.