Circulatory Corticotropin-Releasing Hormone mRNA Concentrations Are Increased in Women with Preterm Delivery But Not in Those Who Respond to Tocolytic Treatment

Stability of placental RNA using dried maternal blood spots

Having demonstrated successful recovery and detection of placental transcripts from dried blood spots (DBS), various preanalytical conditions were examined to determine optimal handling of samples. The role of several factors was explored, including temperature (4 degrees C versus 25 degrees C), processing time (24 h to 8 weeks), and addition of preservatives (RNA later and formalin) that may interfere with stability and detection of placental transcripts in DBS. mRNA transcripts encoding human glyceraldehyde-3-phosphate dehydrogenase (GAPDH; internal control) and beta-human chorionic gonadotrophin (beta HCG; placental) were analysed by real-time-polymerase chain reaction using DBS from 23 pregnant women. GAPDH and beta HCG transcripts were detected in all samples 24 h after collection. Although treatment of blood with RNA later did not affect RNA recovery, formalin treatment negatively affected RNA recovery from DBS. Temperature did not have a significant effect on levels of either transcript. Storage time caused a significant decrease in GAPDH after 4 weeks (P = 0.014) and beta HCG after 1 week (P = 0.007). Decrease of beta HCG levels after 1 week followed by steady detectable levels for up to 4 weeks suggests two populations of circulating placental transcript exist, a population susceptible to degradation in blood versus a more stable form. Therefore, defining proper parameters for collection and storage of DBS further reinforces reliable analysis of target sequences for clinical testing.

Non-invasive prenatal diagnosis: implications for antenatal diagnosis and management of high-risk pregnancies

There has been a huge effort in the last 2-3 decades to develop non-invasive prenatal diagnosis to avoid the risks to the fetus caused by invasive procedures. Obtaining fetal nucleic material for molecular analysis without the need of invasive procedures has been a goal of prenatal diagnosis for many years; this is now been made possible by the use of non-cellular fetal nucleic acids circulating in maternal blood. The placenta is the primary source of these nucleic acids, raising the possibility that they could be a marker for pregnancy complications resulting from placental disease/dysfunction such as pre-eclampsia and fetal growth restriction. If so, these markers might be able to identify cases at risk, predict disease and/or its severity or allow early diagnosis. This has the potential to allow improvements in the management of complicated pregnancies.

Oxidative stress alters the integrity of cell-free mRNA fragments associated with placenta-derived syncytiotrophoblast microparticles

OBJECTIVES

Cell-free fetal RNA from placental origin is present in the peripheral blood of pregnant women. Therefore, its qualitative analysis might provide insights into the physiological condition of the placenta. Here, we examine whether oxidative stress affects the integrity of placentally derived mRNA in vitro.

METHODS

Placental explants were cultured under normal or oxidative conditions, and the levels of placental and syncytiotrophoblast microparticle associated glyceraldehyde-3-phosphate dehydrogenase 3' versus 5' mRNA fragments were analyzed by real-time reverse-transcriptase polymerase chain reaction.

RESULT

The relative ratio of 3' to 5' mRNA fragments associated with placental microparticles was significantly altered upon culture under oxidative stress.

CONCLUSIONS

Our data suggest that oxidative stress reduces the levels of full-length, particle-associated glyceraldehyde-3-phosphate dehydrogenase mRNA transcripts released by the placenta. Therefore, analysis of the microparticle-coupled mRNA integrity in pregnant women might prove useful to diagnose disorders such as preeclampsia, where placental oxidative stress is involved.