The effect of severity of pre-eclampsia on the basal plate intervillous surface lining components: A confocal laser scanning microscopy study

Using immunofluoresce microscopy and histology, intervillous surface lining components area fractions were measured in healthy term chorionic plate (CP) (n=7), healthy term placental basal plate (n=11), mild pre-eclamptic (MPE) placental basal plate (n=10) and severe pre-eclamptic (SPE) placental basal plate (n=11). The aims are (1) to examine the effect of pre-eclampsia (PE) and its severity on the basal plate (BP) intervillous surface lining composition and (2) to define the composition of the CP intervillous surface lining. The results show the mean birth weight of the babies in the SPE are significantly lower than in the HC and MPE (F (2, 29) = 11.912, p =0.000) and the mean gestational age at delivery (GAD) in the SPE group is significantly lower than the HC and MPE (GAD) [Anova p = 0.001; posthoc, p =0.003 and p = 0.001 for MPE and healthy control (HC) respectively]. The mean anchoring villi (AV) to fibrin (NS) ratio of the BP intervillous surface lining is significantly lower in the SPE compared to MPE and the HC groups (ANOVA, p = 0.010; posthoc p = 0.009 and p = 0.628 for HC and MPE respectively) indicating increase fibrin deposition on the basal plate and decreasing anchoring villi attachment area with increasing severity of pre-eclampsia. There are no significant differences in the mean length fractions of endothelium and trophoblast between the 3 groups (Anova, p= 0.107 and p = 0.131 respectively). CP intervillous surface is lined partly by endothelium, trophoblast and an acellular material (fibrin/fibrinoid). Conclusions: (1) The inverse relationship between the proportions of fibrin and anchoring villi with increasing severity of pre-eclampsia indicates that increase deposition of the BP fibrin and poor trophoblast invasion of the BP underlies the disease progression. (2) The CP is partly endothelial contrary to the widely accepted view of wholly trophoblast.