Fetal cells and cell-free fetal DNA in maternal blood: new insights into pre-eclampsia

The examination of fetal cells, specifically erythroblasts, and cell-free fetal DNA from the blood of pregnant women is currently the subject of intense research with the aim of developing new risk-free methods for prenatal diagnosis. An unexpected finding made during these studies was that the traffic of fetal erythroblasts into the maternal peripheral circulation was enhanced in pre-eclampsia. Independent prospective studies examining samples collected in the second trimester indicated that this perturbation in fetal cell trafficking occurs early in pregnancy, well before the onset of pre-eclampsia symptoms. The quantitative analysis of cell-free fetal and maternal DNA levels indicated that these concentrations were elevated in a co-ordinate manner in manifest pre-eclampsia, and that these elevations corresponded to disease severity. On the other hand, analysis of prospectively collected samples indicated that only cell-free fetal but not maternal DNA levels were elevated before onset of symptoms in pregnancies which subsequently developed pre-eclampsia. These data support hypotheses suggesting that pre-eclampsia is a multi-step disorder, initiated by a placental lesion that occurs early in pregnancy and which subsequently leads to a systemic maternal inflammatory response and associated endothelial cell damag

Decrease in lipid levels of syncytiotrophoblast micro-particles reduced their potential to inhibit endothelial cell proliferation

Background: Preeclampsia is characterized by damage to the maternal endothelium that has been suggested to be mediated in part by elevated shedding of inflammatory placental syncytiotrophoblast micro-particles (STBM) into the maternal circulation. Previously, we have shown that STBM, prepared by three different methods: mechanical dissection, in vitro placental explants culture and perfusion of placenta, can inhibit endothelial cell proliferation. Only mechanically prepared STBM induced apoptosis in the endothelial cells. Now, we have examined lipid levels in the three STBM preparations and their differential responses on endothelial cells. Methods: We examined the lipid levels in the three STBM preparations using thin layer chromatography. Furthermore, the effects of reduced lipid levels in the three STBM preparations using the pharmacological agent methyl-β-cyclodextrin were examined on endothelial cell proliferation and apoptosis. Results: Among the three STBM preparations, mechanical STBM contained highest levels of lipids. The reduction in lipid levels in mechanical STBM reduced their potential to inhibit human umbilical vein endothelial cells (HUVEC) proliferation and blocked their potential to induce apoptosis. No similar effect was observed following lipid reduction in the two other STBM preparations. Conclusions: As it has been suggested that mechanically derived STBM may more closely resemble placental micro-particles generated in preeclampsia, our data suggest that lipid content may play a role in the anti-endothelial defects present in this diseas

Role of placentally produced inflammatory and regulatory cytokines in pregnancy and the etiology of preeclampsia

Human pregnancy is a metabolic and immune challenge for the mother who has to accommodate in her womb a semi-allogeneic fetus whose energy needs increase tremendously with gestation. Recent compelling research has suggested that proper inflammatory changes and oxidative balance are a requisite for successful pregnancy. The placenta is an integral component of this inflammatory response as it actively produces a variety of cytokines and immunomodulatory hormones. In preeclampsia, a life-threatening disorder of pregnancy that is characterized by widespread damage and dysfunction of the maternal endothelium, placental oxidative stress and aberrant cytokine expression induces an exaggerated maternal systemic inflammatory response to pregnanc

Is the quantity of circulatory cell-free DNA in human plasma and serum samples associated with gender, age and frequency of blood donations?

Circulatory cell-free DNA (cf-DNA) is increased in a variety of clinical pathologic conditions; therefore, these markers could be widely used as markers for detecting and monitoring several disorders. To better understand the biology of this molecule, we analysed the relationship between the level of circulatory cf-DNA and physiological parameters such as gender, age and frequency of blood donations. Paired plasma and serum samples were obtained from 87 blood donors and 50 healthy adults who had never donated blood. Cf-DNA was extracted from plasma and serum samples using the MagNA Pure LC Instrument. Quantity determination of circulatory cf-DNA was performed by TaqMan real-time PCR for the ubiquitous GAPDH gene. Our data showed that the concentration of cf-DNA in serum was about eightfold higher than that in plasma. Regarding the level of these circulatory species, no significant differences were observed between the age-matched men and women and gender-matched, different-age cohorts, except in women who were older than 60years of age. Frequent blood donations did not increase the circulatory species. Circulatory cf-DNA in plasma and serum samples is not correlated with human gender and human age except in women who are older than 60years of age. Frequent blood donation did not affect the quantity of circulatory cf-DNA. The explanation for the latter most likely is the short half-life time of free fetal DNA in maternal circulatio

Macrophage migration inhibition factor is elevated in pregnancy, but not to a greater extent in preeclampsia

Background: Maternal serum concentrations of macrophage migration inhibitory factor (MIF) have recently been reported to be elevated in cases with preeclampsia. These findings may be important in increasing our understanding of the underlying events leading to the development of preeclampsia, as this cytokine is also expressed in the placenta, where it has been shown to possess immunemodulatory activities. For this reason we attempted to independently verify this report. Methods: Plasma levels of MIF were assessed by ELISA in plasma samples collected from normal healthy male and female blood donors (n=20 per group), as well as healthy normal pregnant women in all three trimesters of pregnancy (n=60). In addition, MIF levels were examined from cases with mild and severe preeclampsia (n=20 per study cohort) and matched normotensive pregnancies (n=20). Results: MIF levels were found to be elevated in pregnancy (median=10.1ng/ml) when compared to non-pregnant controls (median=1.7ng/ml). A moderate, but not significant, elevation was found to occur from the first to the third trimester of pregnancy. No significant difference was found to occur between the two preeclampsia study groups when compared to the normotensive control group. Conclusions: Our data suggest that circulatory MIF concentrations are elevated throughout pregnancy, but are not further increased in preeclampsi

Neutrophil NETs: a novel contributor to preeclampsia-associated placental hypoxia?

Recent studies have suggested that the innate immune system is involved in the pathogenesis of preeclampsia. Its pathogenesis involves neutrophil activation and increased levels of cell-free DNA in the maternal plasma. Activation of neutrophils has recently been shown to induce DNA containing neutrophil extracellular traps (NETs) which trap and kill bacteria. Massive NETs induction by the placentally derived factors (IL-8 and placental micro-debris) and their increased presence in preeclamptic placenta suggest that NETs might be involved in the pathogenesis of preeclampsia. Therefore, increased presence of NETs in preeclampsia may play a role in the deficient placental perfusion associated with this disorde

Prenatal diagnosis of fetal aneuploidies: post-genomic developments

Prenatal diagnosis of fetal aneuploidies and chromosomal anomalies is likely to undergo a profound change in the near future. On the one hand this is mediated by new technical developments, such as chromosomal microarrays, which allow a much more precise delineation of minute sub-microscopic chromosomal aberrancies than the classical G-band karyotype. This will be of particular interest when investigating pregnancies at risk of unexplained development delay, intellectual disability or certain forms of autism. On the other hand, great strides have been made in the non-invasive determination of fetal genetic traits, largely through the analysis of cell-free fetal nucleic acids. It is hoped that, with the assistance of cutting-edge tools such as digital PCR or next generation sequencing, the long elusive goal of non-invasive prenatal diagnosis for fetal aneuploidies can finally be attained

Analysis of plasma elastase levels in early and late onset preeclampsia

Background: Circulatory neutrophils have been reported to be activated in preeclampsia. It has been suggested that maternal plasma levels of elastase may serve as a possible cell-free marker to quantify such activation. Although plasma elastase levels have been found to be elevated in cases with manifest preeclampsia and eclampsia, this has not yet been examined in cases with early and late onset preeclampsia. We have now examined this aspect. Methods: In this retrospective study, maternal plasma samples were examined from eight cases with early onset preeclampsia (34weeks of gestation) and an equal number of gestational age matched normotensive term controls. Plasma concentrations of elastase were measured by ELISA using a commercially available assay. Results: Plasma elastase concentrations were significantly elevated the preeclampsia study group when compared to the normotensive control group (median=139.2ng/ml versus median=72.1ng/ml; P=0.0025). These elevations remained significant when the preeclampsia study group was stratified into case with early onset preeclampsia (median=118.8ng/ml versus median=62.2ng/ml; P=0.03), but jailed failed to attain significance for those cases with late onset preeclampsia (median=181.3ng/ml versus median=86.3ng/ml; P=0.061). Conclusions: Our data indicate that elastase levels are elevated in both early and late onset forms of preeclampsia, and imply that the activation of neutrophils may be more acute in the former than in the latter (238 words