Extracellular vesicle RNAs reflect placenta dysfunction and are a biomarker source for preterm labour

Abstract

Preterm birth (PTB) can lead to lifelong complications and challenges. Identifying and monitoring molecular signals in easily accessible biological samples that can diagnose or predict the risk of preterm labour (PTL) in pregnant women will reduce or prevent PTBs. A number of studies identified putative biomarkers for PTL including protein, miRNA and hormones from various body fluids. However, biomarkers identified from these studies usually lack consistency and reproducibility. Extracellular vesicles (EVs) in circulation have gained significant interest in recent years as these vesicles may be involved in cell‐cell communication. We have used an improved small RNA library construction protocol and a newly developed size exclusion chromatography (SEC)‐based EV purification method to gain a comprehensive view of circulating RNA in plasma and its distribution by analysing RNAs in whole plasma and EV‐associated and EV‐depleted plasma. We identified a number of miRNAs in EVs that can be used as biomarkers for PTL, and these miRNAs may reflect the pathological changes of the placenta during the development of PTL. To our knowledge, this is the first study to report a comprehensive picture of circulating RNA, including RNA in whole plasma, EV and EV‐depleted plasma, in PTL and reveal the usefulness of EV‐associated RNAs in disease diagnosis.

MicroRNA‐transcriptome networks in whole blood and monocytes of women undergoing preterm labour

“…In whole blood, two of the miRNAs (miR‐495‐3p and miR‐381‐3p) with concentration differences in women undergoing sPTL were part of the C14MC region, a group of imprinted miRNAs located on chromosome 14q32 which is highly produced by the placenta and enters maternal circulation . In plasma samples from the same patients, these miRNA concentrations were negatively associated with sPTL, and changes in average expression of C14MC miRNAs in plasma have also been associated with preterm labour . On average, C14MC miRNAs have higher expression and lower variance in the foetal compartment and the placenta compared with the maternal plasma; thus, this signal may be reflecting changes in this compartment .…”

“…They were matched with 30 healthy asymptomatic pregnant women whose blood was taken at the same time‐point during routine clinical visits (gestational age 24‐34 weeks), who later delivered at full term (TL). A full description of this subpopulation is described in other manuscripts . This study was approved by the Research Ethics Board of Mount Sinai Hospital, Toronto, Canada (#04‐0024‐E).…”

“…A full description of this subpopulation is described in other manuscripts. 18,19 This study was approved by the Research Ethics Board of Mount Sinai Hospital, Toronto, Canada (#04-0024-E). All patients provided written consent as part of the OBS at Sinai Health System, Toronto, Canada.…”

“…In our prior analysis of plasma from same patients from the OBS cohort, we identified significant differences in concentration of 132 miRNAs in whole plasma, EVs and EV-depleted plasma. 19 Five of these miRNAs were also significantly different in monocytes, and three miRNAs were significantly different in whole blood (Table S2).…”

“…In order to mitigate batch effects, we eliminated differentially expressed miRNAs which were correlated with order they were loaded onto the array (N = 3 miRNAs in whole blood and monocytes), identified using Spearman's correlation tests with a statistical cut-off of FDR-adjusted q value <.05. We compared expression of miRNA in whole blood and peripheral monocytes to previously published data from the same patient population, including miRNA data from matched plasma and EVs (GSE106224), 19 as well as mRNA expression from whole blood and peripheral monocytes (GSE96097). 18 Putative miRNA targets were detected using the quantitative model TargetScan (V. 7.0, targe tscan.org), which characterizes canonical targeting of miRNAs based on 14 features, and has the best predictive performance compared with comparable tools.…”