Extracellular Vesicles in pregnancy: Their potential role as a liquid biopsy

Objective: Extracellular Vesicles (EVs) are cell-derived particles released during different pathophysiological processes, circulating in many body fluids and mediating the inter-cellular crosstalk. We have analyzed, for the first time, different EV phenotypes and concentrations in the peripheral blood of uncomplicated pregnant women.Study design: In this prospective case-control study, uncomplicated singleton pregnant women at term (N = 59) and aged matched non-pregnant women (N = 21) were enrolled. Freshly drowned peripheral blood samples were stained for flow cytometry analyses of EVs.Results: EVs derived from platelets, leukocytes, endothelial and epithelial cells were identified and counted. Platelet-derived EVs were higher in pregnant compared to non-pregnant women, both in terms of absolute counts (2064.4 +/- 1156.3 vs 701.1 +/- 378.8; p < 0.0001) and percentages (27.6 +/- 17.2 vs 10.7 +/- 5.9; p < 0.0001). The opposite pattern was observed both for concentrations of endothelial-EV counts (525.8 +/- 499.6 vs 844.7 +/- 652.9; p = 0.007) and percentages (6.1 +/- 5.5 vs 11.8 +/- 8.0; p < 0.0001) and leukocyte-derived EV percentages (10.2 +/- 7.4 vs 17.9 +/- 11.2; p = 0.002) EVs. Conclusions: Uncomplicated pregnancies are characterized by a specific EV signature. These cell-derived particles may therefore represent promising biomarkers of different pathological conditions complicating pregnancies, such as preeclampsia or preterm birth.