COVID-19 during pregnancy alters circulating extracellular vesicle cargo and their effects on trophoblast.

SARS-CoV-2 infection and the resulting coronavirus disease (COVID-19) complicate pregnancies as the result of placental dysfunction which increases the risk of adverse pregnancy outcomes. While abnormal placental pathology resulting from COVID-19 is common, direct infection of the placenta is rare. This suggests maternal response to infection is responsible for placental dysfunction. We hypothesized that maternal circulating extracellular vesicles (EVs) are altered by COVID-19 during pregnancy and contribute to placental dysfunction. To examine this, we characterized maternal circulating EVs from pregnancies complicated by COVID-19 and tested their functional effect on trophoblast cells in vitro. We found the timing of infection is a major determinant of the effect of COVID-19 on circulating EVs. Additionally, we found differentially expressed EV mRNA cargo in COVID-19 groups compared to Controls that regulates the differential gene expression induced by COVID-19 in the placenta. In vitro exposure of trophoblasts to EVs isolated from patients with an active infection, but not EVs isolated from Controls, reduced key trophoblast functions including hormone production and invasion. This demonstrates circulating EVs from subjects with an active infection disrupt vital trophoblast function. This study determined that COVID-19 has a long-lasting effect on circulating EVs and circulating EVs are likely to participate in the placental dysfunction induced by COVID-19.