Placental bed spiral arteries in the hypertensive disorders of pregnancy

Abstract

Objective— The investigation of the histology of the placental bed spiral arteries in normal pregnancy and in pregnancies complicated by hypertension, with or without proteinura. Design— An observational study, based on women having caesarean sections for clinical reasons. Subjects— 17 normal pregnant women, 43 with gestational hypertension, of whom 39 had proteinuria, 17 with chronic hypertension, of whom 6 had proteinuria, and 5 with unclassified hypertension. Interventions— Placental bed biopsies obtained during caesarean section. Main outcome measures— Histological appearance of sections stained with haematoxylin and eosin PAS and Lendrum's MSB. Results— Biopsies containing spiral arteries were obtained from 6 normotensive and 44 hypertensive women. Trophoblastic invasion was present in 5 of the 6 normotensive biopsies but absent in the majority of those with hypertension. Subintimal proliferation was seen in all the normotensive biopsies but in only 8 of 28 from those with gestational hypertension and proteinuria. Other features seen predominantly or only in the hypertensive biopsies, in order of frequency, were medial hyperplasia, fibrin deposits, acute atherosis, endothelial vacuolation and thrombosis. Conclusion— Absence of physiological changes may not be peculiar to preeclampsia but may be associated or even a result of various forms of hypertension in pregnancy. Spiral arteries show a spectrum of changes in hypertensive pregnancies that do not appear to bear a clear‐cut relation to the clinical signs.

Summary of the NHLBI Working Group on Research on Hypertension During Pregnancy

“…There may be some superficial remodeling, but it never extends beyond the decidual lining, whereas in normal pregnancy, the modified vessels extend into the inner third of the myometrium. 17 Thus, many vessels in preeclamptic women undergo no remodeling, and this results in reduced placental perfusion. There have been enormous increases in the understanding of human trophoblast invasion, its relation to vascular remodeling, and aberrations that occur in preeclampsia.…”

Quantifying trophoblast migration: In vitro approaches to address in vivo situations

“…Trophoblast-induced remodeling of the spiral arteries results in an increased and constant supply of blood to the placenta as pregnancy progresses, and the importance of this process is highlighted in pregnancy disorders such as pre-eclampsia that are associated with inadequate spiral artery remodeling. 3 As EVTs grow out from the placenta they differentiate from a proliferative phenotype in those cells proximal to the placental villus, to an invasive phenotype capable of migrating into the decidua. Understanding the factors that underlie successful trophoblast invasion and migration is key to understanding how they contribute to normal and abnormal placentation.…”

Notch1 controls development of the extravillous trophoblast lineage in the human placenta

“…The latter deeply migrate into uterine tissue and the maternal spiral arteries, provoking vessel remodelling and adaptation of adequate blood flow to the placenta (5,6). Failures in placentation and artery remodelling have been associated with a variety of pregnancy diseases, such as miscarriage, preeclampsia, fetal growth restriction, and preterm labor (7)(8)(9)(10). Besides unfavorable immunological interactions of EVTs with uterine natural killer (uNK) cells (11), abnormal placental development and trophoblast differentiation are thought to contribute to the pathogenesis of gestational disorders.…”