Consequences of human cytomegalovirus infection on small extracellular vesicles isolated from first trimester placental histocultures

Currently, research on the use of non-invasive biomarkers as diagnosis and prognosis tools during pathological pregnancies is in full development. Among these, the placenta-derived small extracellular vesicles (sEVs) are considered as serious candidates. As such, their composition is modified during many pregnancy pathologies and they can be easily purified from a simple blood sample, as they are found in maternal serum. In this study, we describe the isolation of sEVs from a histoculture model of first trimester placental explants. We characterized these sEVs by a combination of biochemical, bead-based multiplex cytometry and electron microscopy approaches and defined their associated markers and ultrastructure. We next examined the consequences for sEVs secretion and characteristics of placenta infection by the human cytomegalovirus. Under these conditions, the secretion and integrity of sEVs was preserved. However, an increase in the expression level of several surface markers was detected, opening up the prospect for the search for biomarkers predicting the severity and the outcome of this congenital infection early during the pregnancy, which are still sorely lacking.