Analysis of Placenta-derived mRNA in maternal plasma during pregnancy
Purpose: Detection of fetal-derived DNA and RNA molecules in maternal plasma is a promising approach for noninvasive prenatal diagnosis. Placenta-derived mRNA species are readily detectable in maternal plasma. Quantitative analysis of placental mRNAs in maternal plasma provides a way to monitor placental status.
Methods: In this study we measured plasma concentrations of human chorionic gonadotropin beta-subunit (beta-hCG), human placental lactogen (hPL) mRNAs and pregnancy associated plasma protein A (PAPP-A). Peripheral blood samples were taken from 21 subjects at 11 and 24 weeks, from 38 subjects at 15 weeks, from 26 subjects at 36 weeks, from 22 subjects just before delivery, 30 min after delivery, 1 day postpartum and from 10 subjects 1 month after delivery to clarify the time course of placental mRNAs. Blood samples were collected from pregnant women receiving ambulatory prenatal care in the Department of Obstetrics and Gynecology at Hiroshima University Hospital who had provided written informed consent. Plasma was separated from these samples for extraction of RNA, followed by reverse transcription polymerase chain reaction analysis.
Results: Concentrations of hPL mRNA gradually increased during pregnancy to peak (respective medians; 2346.2 and 2397.9 copies/ml) at 36 weeks and just before delivery, while mostly disappearing by the first day of the puerperium. beta-hCG mRNA showed its highest concentration (median; 2819.6 copies/ml) at 11 weeks of pregnancy; although it then declined, it slightly increased just before delivery, then largely disappearing by the first day of the puerperium. PAPP-A mRNA increased gradually during pregnancy, attaining highest concentrations just before and after delivery (respective medians: 5410.0 and 6498.4 copies/ml), and then decreasing on the first day of the puerperium.
Conclusions: Quantitative analysis of several placental mRNAs in maternal plasma might represent a useful way to monitor placental status.