Plasma Extracellular Vesicle and miRNA Profiles in Pregnancies Complicated by Fetal Congenital Heart Defects

Congenital heart defects (CHDs) are the most common form of fetal malformation however, our understanding of trophoblast health and communication throughout gestation in CHD pregnancies remains limited. The purpose of this study was to assess extracellular vesicles (EVs) and microRNA (miRNA) present in maternal and umbilical cord plasma from a spectrum of CHD subtypes during gestation and at time of delivery. We hypothesized that circulating placenta-derived EVs and miRNA will differ in CHD when compared to controls. Maternal plasma samples were collected between 16-24 weeks of gestation and at the time of delivery. Umbilical cord plasma was obtained following delivery. EVs were isolated from plasma samples using nanoscale flow cytometry, and total EV counts as well as counts by cellular origin were determined. MicroRNA was extracted from maternal plasma and levels quantified using qPCR. Maternal plasma from pregnancies complicated by fetal CHD exhibited higher total EV counts at delivery compared to control. Platelets derived extracellular vesicles (pdEVs) were significantly higher both in maternal and cord blood plasma at the time of delivery in CHD pregnancies compared to gestationally age-matched control pregnancies. Circulating miR22 and miR421 levels were reduced, while miR29c levels were increased in maternal plasma from CHD pregnancies between 16-24 weeks but no differences seen at time of delivery. Pregnancies complicated by CHD are associated with an altered in utero environment by changes in extracellular vesicles and miRNA profile in maternal serum. Circulating EVs and miRNA profiles may therefore serve as minimally invasive indicators of placental and maternal vascular dysfunction in CHD.