Measurement of mRNA Transcripts of Very High Placental Expression in Maternal Blood as Biomarkers of Preeclampsia

Context: mRNA of placental origin in maternal blood shows potential as a clinical biomarker of obstetric diseases such as preeclampsia (PE). We hypothesized that mRNA transcripts very highly expressed in the placenta relative to other tissues will be differentially expressed in PE and be useful as mRNA biomarkers in maternal blood. Objective: Our objective was to identify a panel of genes highly expressed in the placenta and compare their expression in placenta and maternal whole blood from PE vs. control pregnancies. Setting: Placental tissue and maternal whole blood specimens were obtained from normotensive controls (n = 15) and pregnancies complicated by severe preterm PE (n = 21). Intervention: mRNA expression was evaluated by quantitative real-time RT-PCR. Results: We identified 20 genes exhibiting highest to fourth highest expression in the placenta relative to all other tissues. All genes were detectable in placenta. Nine of the 20 genes were detectable in maternal whole blood. Four of the nine genes detectable in blood (i.e. PLAC3, PLAC4, CRH, and ERVWE1) were significantly increased in both maternal blood and placenta from PE pregnancies. The remaining five genes detectable in maternal blood were unchanged in both blood and placenta from PE pregnancies. Thus, there was complete correlation of gene expression between maternal blood and placenta. Conclusions: Circulating mRNA coding genes of high placental expression show strong correlation with transcript levels in preeclamptic placenta. Such transcripts may be promising candidates to screen as mRNA biomarkers of PE in maternal whole blood. (J Clin Endocrinol Metab 96: E1807-E1815, 2011)