Introduction: Preeclampsia is a major pregnancy complication. Placental factor/toxin triggers maternal endothelial cell activation and inflammation. Trophoblast debris may be one placental trigger of preeclampsia. Trophoblast debris is dead cellular material shed from the placenta into the maternal blood and ranges in size from large multinucleated syncytial nuclear aggregates down to trophoblast microparticles. Trophoblast microparticles are membrane bound structures whose exact origin is not known. These microparticles may result from the shedding of microvilli from the syncytiotrophoblast or they may be apoptotic bodies produced as part of the trophoblast life cycle. In this study we investigated the effects of exposing endothelial cells to trophoblast microparticles obtained from placental explants that had been cultured with serum from women with preeclampsia or normotensive pregnancies.
Methods: Replicate placental explants from normal pregnancies first trimester pregnancies were labelled with cell-tracker red stain and incubated with medium containing 10% FBS or serum from each of 12 women with preeclampsia or 12 gestation-matched normotensive pregnant women. Trophoblast debris was collected and microparticles separated from the larger debris by differential centrifugation. Microparticles were exposed to monolayers of HMEC-1 endothelial cells for 24 hours. The fate of the microparticles was observed by confocal microscopy and quantified by fluorescent microplate reader. Endothelial cell responses were investigated by quantifying cell-surface ICAM-1 and IL-1beta in the media by ELISA.
Results:
1) Confocal microscopy demonstrated that endothelial cells contained labelled microparticles.
2) The density of microparticles in the endothelial cells increased in a time-dependent manner.
3) Microparticles from explants treated with preeclamptic but not normotensive serum activated endothelial cells.
Conclusion: Our results demonstrate that microparticles from placental explants treated with preeclamptic but not normotensive sera activated endothelial cells. This suggests a factor in preeclamptic sera changes the nature and/or number of microparticles extruded from placentae.