Peptide hormone ELABELA enhances extravillous trophoblast differentiation, but placenta is not the major source of circulating ELABELA in pregnancy

Preeclampsia is a frequent gestational hypertensive disorder with equivocal pathophysiology. Knockout of peptide hormone ELABELA (ELA) has been shown to cause preeclampsia-like symptoms in mice. However, the role of ELA in human placentation and whether ELA is involved in the development of preeclampsia in humans is not yet known. In this study, we show that exogenous administration of ELA peptide is able to increase invasiveness of extravillous trophoblasts in vitro, is able to change outgrowth morphology and reduce trophoblast proliferation ex vivo, and that these effects are, at least in part, independent of signaling through the Apelin Receptor (APLNR). Moreover, we show that circulating levels of ELA are highly variable between women, correlate with BMI, but are significantly reduced in first trimester plasma of women with a healthy BMI later developing preeclampsia. We conclude that the large variability and BMI dependence of ELA levels in circulation make this peptide an unlikely candidate to function as a first trimester preeclampsia screening biomarker, while in the future administering ELA or a derivative might be considered as a potential preeclampsia treatment option as ELA is able to drive extravillous trophoblast differentiation.