Circulatory fetal and maternal DNA in pregnancies at risk and those affected by preeclampsia

The role of neutrophils and neutrophil extracellular traps (NETs) in stages, outcomes and pregnancy complications

Neutrophils are the main components of innate immunity to eliminate infectious pathogens. Neutrophils play a role in several stages of the reproductive cycle, and their presence in the female reproductive system is highly regulated, so their function may change during pregnancy. Emerging evidence suggests that neutrophils are important at all stages of pregnancy, from implantation, placentation, and connective tissue regeneration to birth, as well as birth itself. Neutrophil extracellular traps (NETs) are defined as extracellular strands of unfolded DNA together with histone complexes and neutrophil granule proteins. NET formation is a new mechanism of these cells for their defense function. These strands containing DNA and antimicrobial peptides were initially recognized as one of the defense mechanisms of neutrophils, but later it was explained that they are involved in a variety of non-infectious diseases. Since the source of inflammation and tissue damage is the irregular activity of neutrophils, it is not surprising that NETosis are associated with a number of inflammatory conditions and diseases. The overexpression of NET components or non-principled NET clearance is associated with the risk of production and activation of autoantibodies, which results in participation in autoinflammatory and autoimmune disorders (SLE, RA), fibrosis, sepsis and other disorders such as vascular diseases, for example, thrombosis and atherosclerosis. Recent published articles have shown the role of neutrophils and extracellular traps (NETs) in pregnancy, childbirth and pregnancy-related diseases. The aim of this study was to identify and investigate the role of neutrophils and neutrophil extracellular traps (NETs) in the stages of pregnancy, as well as the complications caused by these cells.

Detection of serum major histocompatibility complex I (HLA-1) and β2-microglobulin (β2M) in pre-eclampsia using isobaric tags for relative and absolute quantitation (iTRAQ)

OBJECTIVE

The purpose of this preliminary investigation into the pathogenesis of pre-eclampsia was to screen the differential proteins in the serum of pregnant women with normal pregnancy and early-onset pre-eclampsia using isobaric tags for relative and absolute quantitation (iTRAQ), so as to identify serum biomarkers for the early diagnosis of pre-eclampsia.

METHODS

We examined the peripheral serum of 58 normal pregnant women and 42 pregnant women with early-onset pre-eclampsia using iTRAQ; the differentially expressed proteins were screened for bioinformatics analysis; and the expression of candidate proteins human leukocyte antigen-1 (HLA-1) and β2-microglobulin (β2M) in placental tissues was detected using western blot.

RESULTS

We identified a total of 63 differential proteins in the serum of patients from the normal control group and the pre-eclampsia group, and this included 24 up-regulated proteins and 39 down-regulated proteins. The western blot results of placental tissue showed reduced HLA-1 expression (1.12 ± 0.23) in the placenta in the pre-eclampsia group as compared with the normal control group (1.34 ± 0.22). Consistent with the results observed in the serum, β2M in the placenta in the pre-eclampsia group was significantly elevated (1.05 ± 0.47) in comparison with the normal group (0.75 ± 0.33) (P < 0.05).

CONCLUSION

In this study, we found that iTRAQ technology was useful for identifying differentially expressed proteins in the peripheral serum of pregnant women with pre-eclampsia, and that HLA-1 and β2M, which may be involved in the occurrence of pre-eclampsia, show promise as predictive markers of pre-eclampsia.

Circulating Nucleic Acids in Maternal Plasma and Serum in Pregnancy Complications: Are They Really Useful in Clinical Practice? A Systematic Review

OBJECTIVE

A systematic review was carried out to summarize the available evidence to assess whether circulating nucleic acids in maternal plasma and serum (CNAPS) have the potential to serve as extra and independent markers for the prediction and/or progression monitoring of the most common and severe complications of pregnancy, including preeclampsia, intrauterine growth restriction, preterm delivery, morbidly adherent placenta, gestational diabetes, antiphospholipid syndrome, threatened abortion, intrahepatic cholestasis of pregnancy, and hyperemesis gravidarum.

METHOD

A comprehensive literature search of the MEDLINE (PubMed), EMBASE, and ISI Web of Knowledge databases was conducted to identify relevant studies that included amounts of CNAPS in the abovementioned pregnancy complications.

RESULTS

Eighty-three studies met the eligibility criteria. The vast majority of studies were conducted on the quantity of total circulating cell free DNA (cfDNA) and cell free fetal DNA (cffDNA), and some were conducted on messenger RNA (mRNA) species. A few studies have instead evaluated the cell free DNA fetal fraction (cfDNAff), but only in a limited number of pregnancy complications. Despite the growing interest and the abundance of the papers available, little information is available for other new CNAPS, including microRNA (miRNA), long noncoding RNA (lncRNA), mitochondrial DNA (mtDNA), and circular RNA.

CONCLUSION

Due to the heterogeneity of the populations enrolled, the scarcity of the studies that adjusted the CNAPS values for possible confounding factors, and the difficulty in interpreting the published data, no conclusion regarding the statistical robustness and clinical relevance of the data can be made at present. If assayed at the third trimester, the CNAPS have, however, shown better performance, and could be used in populations already at risk of developing complications as suggested by the presence of other clinical features. Other CNAPS, including miRNA, are under investigation, especially for the screening of gestational diabetes mellitus, but no data about their clinical utility are available. Circulating DNA (cfDNA, cffDNA, and cfDNAff) and mRNA have not been properly evaluated yet, especially in patients asymptomatic early in pregnancy but who developed complications later, perhaps because of the high cost of these techniques and the availability of other predictors of pregnancy complications (biochemical, biophysical, and ultrasound markers). Therefore, from the analysis of the data, the positive predictive value is not available. As regards the new CNAPS, including miRNA, there are still no sufficient data to understand if they can be promising markers for pregnancy complications monitoring and screening, since CNAPS are statistically weak and expensive. It is reasonable to currently conclude that the use of the CNAPS in clinical practice is not recommended.

Sex of the first-born and obstetric complications in the subsequent birth. A study of 2.3 million second births from Denmark, Finland, Norway, and Sweden

INTRODUCTION

Studies have shown associations between a first-born boy and increased risks of pregnancy loss, stillbirth, decreased birthweight, and preterm birth in subsequent pregnancies, but with limited precision.

MATERIAL AND METHODS

We examined associations between sex of the first-born and obstetric complications in second births. We calculated the relative risks (RR)s of preeclampsia/eclampsia, placental abruption, stillbirth, and preterm birth in approximately 2.3 million second births comparing women with a preceding first-born boy to those with a first-born girl using the Medical Birth Registries of Denmark, Finland, Norway, and Sweden 1980-2008.

RESULTS

In second births following a first-born boy rather than a girl, the RR was 4% higher for preeclampsia/eclampsia (RR = 1.04, 95% CI 1.02-1.06), 9% higher for placental abruption (RR = 1.09, 95% CI 1.05-1.13), 9% higher for stillbirth (RR = 1.09, 95% CI 1.04-1.14), and 8% higher for preterm birth (RR = 1.08, 95% CI 1.07-1.09). The population attributable risks ranged from 2% to 4.5%.

CONCLUSIONS

Male sex of the first-born is associated with small increases in risks of obstetric complications in the second birth. Exploration of the underlying mechanisms is needed to increase our knowledge and treatment options for these serious obstetric complications.

Inflammation-The role of ATP in pre-eclampsia

Sterile inflammation may be initiated by molecules in the host organism that signal "damage" or "danger" also known as danger-associated molecular pattern (DAMPs). In pre-eclampsia (PE), a variety of DAMPs may be involved in the etiology or exacerbation of the disorder. Adenosine 5'-triphosphate (ATP) is a key intracellular energy molecule as well as a ligand for purinergic receptors. In humans, under physiological conditions, extracellular ATP (eATP) levels are distinctly low, but can rise to several hundred fold when cells become injured, stressed, or even necrotic. This often initiates a sterile inflammatory response with eATP acting as a DAMP. Extracellular ATP and its derivative nucleotides synthetized by endonucleotidases exhibit many of their effects through purinergic receptors, via inflammatory cascades and the production of proinflammatory molecules. This is clearly seen in the P2X₇ gated receptor, which is linked to release of cytokines of the interleukin-1 family. Considering its fundamental role in innate immunity, an imbalance of P2X₇ receptor activation may lead to deleterious effects in the coordination of placental vessel tone via the synthesis of various proinflammatory cytokines. This review explores the implication of DAMPs, specifically ATP and uric acid in the inflammation associated with PE.

The impact of previous live births on peripheral and uterine natural killer cells in patients with recurrent miscarriage

BACKGROUND

Peripheral and uterine natural killer cells (pNK and uNK cells) are key players in the establishment and maintenance of pregnancy and are disturbed in patients with recurrent miscarriage (RM). Different immunologic risk factors have been proposed between patients with primary RM (pRM, no previous live birth) and secondary RM (sRM, ≥ 1 previous live birth). However, so far, the study populations mainly consisted of small subgroups. Therefore, we aimed to analyse pNK and uNK cells in a large, well defined study population within a prospective study.

METHODS

In total, n = 575 RM patients (n = 393 pRM, n = 182 sRM) were screened according to a standard protocol for established risk factors as well as pNK and uNK cells. Peripheral blood levels of CD45⁺CD3^-CD56⁺CD16⁺ NK cells were determined by flow cytometry and uterine CD56⁺ NK cells by immunohistochemistry in mid-luteal non-pregnant RM patients. Exclusion of patients with ≥1 established risk factor revealed n = 248 idiopathic RM patients (iRM, n = 167 primary iRM (ipRM), n = 81 secondary iRM (isRM)).

RESULTS

Patients with pRM and ipRM showed significant higher absolute numbers and percentages of pNK cells compared to sRM and isRM patients (pRM/ipRM vs sRM/isRM, mean ± SD /μl: 239.1 ± 118.7/244.9 ± 112.9 vs 205.1 ± 107.9/206.0 ± 105.6, p = 0.004/ p = 0.009; mean ± SD %: 12.4 ± 5.5/12.8 ± 5.4 vs 11.1 ± 4.6/11.1 ± 4.3, p = 0.001; p = 0.002). Only patients with isRM showed significantly higher uNK levels compared to patients with ipRM (mean ± SD /mm² 288.4 ± 239.3 vs 218.2 ± 184.5, p = 0.044).

CONCLUSIONS

The demonstrated differences in pNK and uNK cells in RM patients depending on previous live birth might indicate differences in NK cell recruitment and potentially different underlying immune disorders between pRM and sRM. As there is an overlap in the distribution of the NK cell results, further studies with focus on NK cell function are needed in order to clearly identify RM patients with distinct immune abnormalities. The clinical relevance of our findings should be interpreted cautiously until specificity and sensitivity are further evaluated.

Feto-Maternal Microchimerism: The Pre-eclampsia Conundrum

Feto-maternal microchimerism (FMM) involves bidirectional cross-placental trafficking during pregnancy, leading to a micro-chimeric state that can persist for decades. In this manner a pregnant woman will harbor cells from her mother, as well as, cells from her child. Historically, eclampsia, a severe disorder of pregnancy provided the basis for FMM following the detection of trophoblast cells in the lungs of deceased women. Bi-directional cell trafficking between mother and fetus is also altered in pre-eclampsia and has been suggested to contribute to the underlying etiology. FMM has been implicated in tolerance promotion, remission of auto-inflammatory disorders during pregnancy, or the development of autoimmune conditions post-partum. The underlying mechanism whereby the host immune system is modulated is unclear but appears to involve HLA class II molecules, in that incompatibility between mother and fetus promotes remission of rheumatoid arthritis, whereas feto-maternal HLA compatibility may assist in the post-partum initiation of scleroderma. Couples having a high degree of HLA class II compatibility have an increased risk for pre-eclampsia, while the occurrence of scleroderma and rheumatoid arthritis is greater in pre-eclamptic cases than in women with normal pregnancies, suggesting a long term autoimmune predisposition. Since pregnant women with pre-eclampsia exhibit significantly lower levels of maternally-derived micro-chimerism, the question arises whether pre-eclampsia and post-partum development of autoimmune conditions occur due to the failure of the grandmothers cells to adequately regulate an inappropriate micro-chimeric constellation.

Levels of Circulating Cell-Free Serum DNA in Benign and Malignant Breast Lesions

Purposes of the study: We analyzed circulating cell-free DNA in the serum of patients with benign and malignant breast disease and in healthy individuals to determine its diagnostic value.

Basic procedures: Serum samples were obtained from 50 healthy individuals, 33 patients with malignant breast disease and 32 patients with benign breast disease. Circulatory DNA was extracted from serum samples. Cell-free DNA was quantified by real-time quantitative PCR for the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. Tissue samples from patients with malignant and benign breast lesions were histopathologically examined.

Main findings: The mean levels of circulating cell-free DNA in serum samples were 41,149 genome equivalents (GE)/mL in patients with malignant disease, 30,826 GE/mL in patients with benign disease, and 13,267 GE/mL in healthy individuals. Healthy individuals had significantly lower levels of cell-free DNA than patients with malignant or benign breast disease (p=0.001, p=0.031). No significant difference was observed between malignant and benign disease. There was a correlation between cell-free DNA levels and tumor size but not with other tumor characteristics.

Principal conclusion: Our results suggest that levels of circulating cell-free DNA in serum could have diagnostic value to discriminate between healthy individuals and patients with breast lesions but not between patients with malignant and benign breast lesions.

Excessive Neutrophil Activity in Gestational Diabetes Mellitus: Could It Contribute to the Development of Preeclampsia?

Gestational diabetes mellitus is a transient form of glucose intolerance occurring during pregnancy. Pregnancies affected by gestational diabetes mellitus are at risk for the development of preeclampsia, a severe life threatening condition, associated with significant feto-maternal morbidity and mortality. It is a risk factor for long-term health in women and their offspring. Pregnancy has been shown to be associated with a subliminal degree of neutrophil activation and tightly regulated generation of neutrophil extracellular traps (NETs). This response is excessive in cases with preeclampsia, leading to the presence of large numbers of NETs in affected placentae. We have recently observed that circulatory neutrophils in cases with gestational diabetes mellitus similarly exhibit an excessive pro-NETotic phenotype, and pronounced placental presence, as detected by expression of neutrophil elastase. Furthermore, exogenous neutrophil elastase liberated by degranulating neutrophils was demonstrated to alter trophoblast physiology and glucose metabolism by interfering with key signal transduction components. In this review we examine whether additional evidence exists suggesting that altered neutrophil activity in gestational diabetes mellitus may contribute to the development of preeclampsia.

Gestational Diabetes Mellitus Is Associated with Altered Neutrophil Activity

Gestational diabetes mellitus (GDM) is a unique form of glucose intolerance, in that it is transient and solely occurs in pregnancy. Pregnancies with GDM are at high risk of developing preeclampsia (PE), a leading cause of fetal and maternal morbidity or mortality. Since PE is associated with excessive activation of circulatory neutrophils and occurrence of neutrophil extracellular traps (NETs) in affected placentae, we examined these features in cases with GDM, as this could be a feature linking the two conditions. Our data indicate that neutrophil activity is indeed altered in GDM, exhibiting pronounced activation and spontaneous generation of NETs by isolated neutrophils in in vitro culture. In this manner, GDM may similarly affect neutrophil behavior and NET formation as witnessed in other forms of diabetes, with the addition of the physiological changes mediated by pregnancy. Since circulatory TNF-α levels are elevated in cases with GDM, a feature also observed in this study, we examined whether this pro-inflammatory cytokine contributed to neutrophil activation. By using infliximab, a clinically utilized TNF-α antagonist, we observed that the pro-NETotic effect of GDM sera was significantly reduced. We also detected pronounced neutrophil infiltrates in placentae from GDM cases. The occurrence of NETs in these tissues is suggested by the extracellular co-localization of citrullinated histones and myeloperoxidase. In addition, elevated neutrophil elastase (NE) mRNA and active enzymatic protein were also detected in such placentae. This latter finding could be important in the context of previous studies in cancer or diabetes model systems, which indicated that NE liberated from infiltrating neutrophils enters surrounding cells, altering cell signaling by the degradation of IRS1. These findings could potentiate the underlying inflammatory response process in GDM and possibly open an avenue for the therapeutic interventions in gestational hyperglycemia.

Fetal-specific hypermethylated RASSF1A quantification in pregnancy

OBJECTIVE

To quantify cell free fetal DNA (cffDNA) with fetal specific epigenetic marker, hypermethylated RASSF1A, in maternal plasma of normal pregnant women from 20 weeks of gestation and to assess its relationship with maternal age, height, pre-pregnancy weight and body mass index (BMI).

METHODS

Hundred normal pregnant women within the gestational age of 21-40 weeks were randomly selected and grouped into five (n = 20). Group 1: 21-24, Group 2: 25-28, Group 3: 29-32, Group 4: 33-36 and Group 5: 37-40 weeks. Maternal plasma DNA was extracted, digested with methylation-sensitive restriction enzyme, BstUI and the fetal specific DNA (cffDNA) was quantified by Real-time polymerase chain reaction (qRT-PCR).

RESULTS

The mean hypermethylated RASSF1A concentrations in different gestational groups were Group 1: 30.1 ± 14.9, Group 2: 52.6 ± 22.18, Group 3: 93.2 ± 19.08, Group 4: 172.8 ± 26.81 and Group 5: 337.8 ± 52.9 copies/ml. Pearson's correlation analysis showed highly significant positive correlation between cffDNA and gestational age (r = 0.899, p < 0.001). BMI was also found to be positively related to cffDNA (r = 0.217, p < 0.05). However, it did not show any correlation with maternal age, height and pre-pregnancy weight.

CONCLUSIONS

The gestational age-dependent increase of hypermethylated RASSF1A; the fetal specific epigenetic marker in maternal plasma was demonstrated, in an Indian study group of normal pregnant women. Findings would form the basis of future studies involving pregnancy complications that would aid in the early diagnosis of placental pathologies with hypermethylated RASSF1A.

Elevated Levels of Total Cell-Free DNA in Maternal Serum Samples Arise from the Generation of Neutrophil Extracellular Traps

INTRODUCTION

The analysis of cell-free DNA from maternal blood samples has facilitated the noninvasive detection of fetal aneuploidies or hereditary Mendelian disorders. In this context, previous studies have indicated that the pool of cell-free DNA is greater in maternal serum than in plasma samples, necessitating optimized collection and storage protocols. As the source of this increased amount of cell-free DNA is not clear, we have now examined whether neutrophil extracellular traps (NETs) contribute to this material.

MATERIAL AND METHODS

Serum samples were collected in all three trimesters of normal healthy pregnant women, and at term from cases with manifest preeclampsia. The presence of NET-derived material was demonstrated by the detection of cell-free DNA fragments complexed to neutrophil granular proteins (i.e. myeloperoxidase).

RESULTS

Our data indicate that NET-derived cell-free DNA/myeloperoxidase complexes were greater in serum from normal pregnant women than in normal matching nonpregnant controls. This neutrophil chromosomal material increased incrementally throughout gestation and was most pronounced in cases with preeclampsia.

DISCUSSION

By detecting increased levels of cell-free DNA/myeloperoxidase complexes in maternal serum samples, our data indicate that a significant proportion of this material is derived from the generation of NETs.

The Most Favourable Procedure for the Isolation of Cell-Free DNA from the Plasma of Iso-Immunized RHD-Negative Pregnant Women

BACKGROUND

The ability to achieve quality recovery of cell-free foetal DNA is important for making non-invasive prenatal diagnoses. In this study, we performed quantitative and qualitative analyses of isolated DNA from maternal plasma, using different DNA-isolation methods.

METHOD

DNA was isolated from 30 iso-immunized women via the QIAamp column-based method, using four different elution volumes and two conventionally based methods. Real-time polymerase chain-reaction quantification of RHD and β-globin genes was performed in order to determine foetal-specific sequences and total genome equivalents, respectively.

RESULTS

The column-based method at a 3 μl elution volume yielded the highest quality and quantity of total DNA (67.0±0.6 ng/μL). At a 3 μl elution volume, the β-globin and RHD-gene sequences were estimated to be the highest among all isolation procedures, with 2778.13±1.5 and 66.9±0.6 GEq/mL, respectively, and a 100% sensitivity for RHD-gene sequence detection. Among the two conventional manual methods, the boiling lysis method yielded a higher DNA concentration (53.8±0.8 ng/μL) and purity (1.73±0.05). In addition, the method's sensitivity for foetal-detection sequences was only 80%, whereas the salting-out method's sensitivity was just 70%.

CONCLUSIONS

This study confirms the theory that the QIAamp method is a specific and sensitive approach for purifying and quantifying plasma DNA, when used in the minimum elution volume.

Current approaches on non-invasive prenatal diagnosis: Prenatal genomics, transcriptomics, personalized fetal diagnosis

Recent developments in molecular genetics improved our knowledge on fetal genome and physiology. Novel scientific innovations in prenatal diagnosis have accelerated in the last decade changing our vision immensely. Data obtained from fetal genomic studies brought new insights to fetal medicine and by the advances in fetal DNA and RNA sequencing technology novel treatment strategies has evolved. Non-invasive prenatal diagnosis found ground in genetics and the results are widely studied in scientific arena. When Lo and colleges proved fetal genetic material can be extracted from maternal plasma and fetal DNA can be isolated from maternal serum, the gate to many exciting discoveries was open. Microarray technology and advances in sequencing helped fetal diagnosis as well as other areas of medicine. Today it is a very crucial prerequisite for physicians practicing prenatal diagnosis to have a profound knowledge in genetics. Prevailing practical use and application of fetal genomic tests in maternal and fetal medicine mandates obstetricians to update their knowledge in genetics. The purpose of this review is to assist physicians to understand and update their knowledge in fetal genetic testing from maternal blood, individualized prenatal counseling and advancements on the subject by sharing our experiences as İstanbul University Fetal Nucleic Acid Research Group.

Neutrophil NETs in reproduction: from infertility to preeclampsia and the possibility of fetal loss

The intention of this review is to provide an overview of the potential role of neutrophil extracellular traps (NETs) in mammalian reproduction. Neutrophil NETs appear to be involved in various stages of the reproductive cycle, starting with fertility and possibly ending with fetal loss. The first suggestion that NETs may play a role in pregnancy-related disorders was in preeclampsia, where vast numbers were detected in the intervillous space of affected placentae. The induction of NETosis involved an auto-inflammatory component, mediated by the increased release of placental micro-debris in preeclampsia. This report was the first indicating that NETs may be associated with a human pathology not involving infection. Subsequently, NETs have since then been implicated in bovine or equine infertility, in that semen may become entrapped in the female reproductive tract during their passage to the oocyte. In this instance interesting species-specific differences are apparent, in that equine sperm evade entrapment via expression of a DNAse-like molecule, whereas highly motile bovine sperm, once free from seminal plasma (SP) that promotes interaction with neutrophils, appear impervious to NETs entrapment. Although still in the realm of speculation it is plausible that NETs may be involved in recurrent fetal loss mediated by anti-phospholipid antibodies, or perhaps even in fetal abortion triggered by infections with microorganisms such as L. monocytogenes or B. abortus.

Can detection of late-onset PE at triage by sflt-1 or PlGF be improved by the use of additional biomarkers?

OBJECTIVE

Accurate identification of preeclampsia (PE) at triage is essential to reduce maternal and fetal morbidity and mortality. The use of maternal blood based biomarkers may facilitate the clinician's ability to assess high risk pregnancies at triage.

METHODS

A prospective cross-sectional study was performed to investigate the value of soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), placental growth factor (PlGF), sP-selectin, cell-free fetal DNA and total cell-free DNA in patients with late-onset PE versus gestational age-matched controls.

RESULTS

The diagnosis of late-onset PE (n = 21) at triage was significantly improved by altered levels of sFlt-1, sEng, PlGF and cffDNA as compared with controls (n = 42). Areas under the receiver operating characteristic curves [AUC, Standard error (SE)] for predicting PE were for marker measurements prior to the first stage of labor as follows: sFlt-1 0.97 (SE 0.02), sEng 0.91 (SE 0.04), PlGF 0.95 (SE 0.04), cell-free fetal DNA (DYS 14) 0.84 (SE 0.06), total cell-free DNA (glyceraldehyde 3-phosphate dehydrogenase) 0.61 (SE 0.07), sP-selectin 0.51 (SE 0.07). The discrimination could be slightly improved by using the slt1-PlGF ratio: 0.98 (SE 0.02).

CONCLUSION

The sFlt-1 is a useful tool for the detection of late-onset PE at triage. This can be slightly improved using a sFlt-1/PIGF ratio. The addition of other biomarkers did not improve screening performance for late-onset PE.

Epigenetics and microRNAs in preeclampsia

Strong evidence suggests a potential link among epigenetics, microRNAs (miRNAs), and pregnancy complications. Much research still needs to be carried out to determine whether epigenetic factors are predictive in the pathogenesis of preeclampsia (PE), a life-threatening disease during pregnancy. Recently, the importance of maternal epigenetic features, including DNA methylation, histone modifications, epigenetically regulated miRNA, and the effect of imprinted or non-imprinted genes on trophoblast growth, invasion, as well as fetal development and hypertension in pregnancy, has been demonstrated in a series of articles. This article discusses the current evidence of this complicated network of miRNA and epigenetic factors as potential mechanisms that may underlie the theories of disease for PE. Translating these basic epigenetic findings to clinical practice could potentially serve as prognostic biomarkers for diagnosis in its early stages and could help in the development of prophylactic strategies.

The presence of HLA-antibodies in recurrent miscarriage patients is associated with a reduced chance of a live birth

Anti-paternal HLA-antibodies are considered a harmless phenomenon during most pregnancies, whereas their role in recurrent miscarriage (RM) patients is disputed. In contrast to primary RM, patients with secondary RM have carried a fetus to term pregnancy prior to a series of miscarriages, which increases the chance that allogeneic fetal cells appear in the maternal circulation. This study investigates the frequency of HLA-antibodies in secondary RM, primary RM patients and parous controls and analyzes whether the presence of HLA-antibodies in early pregnancy is associated with pregnancy outcome. Sera from women with secondary RM (n=56), primary RM (n=13) and parous controls (n=24) were tested for HLA-antibodies using an ELISA assay and complement dependent cytotoxicity. Samples were taken at gestational week 4-5 in 62 (90%) of the patients. HLA-antibodies were significantly more frequent in secondary RM patients with a boy prior to the miscarriages (62%) compared to secondary RM patients with a firstborn girl (29%, p=0.03), primary RM patients (23%, p=0.02) and parous controls (25%, p=0.005). Forty-one percent of HLA-antibody positive pregnant RM patients had a live birth compared to 76% of HLA-antibody negative RM patients, p=0.006 (adjusted OR: 0.22 (0.07-0.68), p=0.008). In conclusion, HLA-antibodies are significantly more frequent in secondary RM patients with a firstborn boy than in other RM patients and controls. The presence of these antibodies in early pregnancy is associated with a reduced chance of a live birth. Further exploring this association may increase our understanding of maternal acceptance of the fetal allograft.

Circulating predictive biomarkers in preeclampsia

The aim of the paper was to review promising prediction biomarkers for preeclampsia. The methods included review of abstracts on PubMed, using "preeclampsia", "biomarker", "prediction" as key words, followed by review of primary papers investigating blood based biomarkers. Angiogenic factors, such as PlGf and sFlt1, and PP13 seem presently to have the best predictive test values for preeclampsia, but sensitivity and specificity is still too low to prove useful in a population screening setting. Biomarker testing should still be part of research protocols. Biomarkers could provide useful in selecting high-risk women for prophylactic trials as well as identifying pregnancies that could profit from closer follow-up.

Levels of plasma circulating cell free nuclear and mitochondrial DNA as potential biomarkers for breast tumors

Background

With the aim to simplify cancer management, cancer research lately dedicated itself more and more to discover and develop non-invasive biomarkers. In this connection, circulating cell-free DNA (ccf DNA) seems to be a promising candidate. Altered levels of ccf nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) have been found in several cancer types and might have a diagnostic value.

Methods

Using multiplex real-time PCR we investigated the levels of ccf nDNA and mtDNA in plasma samples from patients with malignant and benign breast tumors, and from healthy controls. To evaluate the applicability of plasma ccf nDNA and mtDNA as a biomarker for distinguishing between the three study-groups we performed ROC (Receiver Operating Characteristic) curve analysis. We also compared the levels of both species in the cancer group with clinicopathological parameters.

Results

While the levels of ccf nDNA in the cancer group were significantly higher in comparison with the benign tumor group (P < 0.001) and the healthy control group (P < 0.001), the level of ccf mtDNA was found to be significantly lower in the two tumor-groups (benign: P < 0.001; malignant: P = 0.022). The level of ccf nDNA was also associated with tumor-size (<2 cm vs. >2 cm<5 cm; 2250 vs. 6658; Mann-Whitney-U-Test: P = 0.034). Using ROC curve analysis, we were able to distinguish between the breast cancer cases and the healthy controls using ccf nDNA as marker (cut-off: 1866 GE/ml; sensitivity: 81%; specificity: 69%; P < 0.001) and between the tumor group and the healthy controls using ccf mtDNA as marker (cut-off: 463282 GE/ml; sensitivity: 53%; specificity: 87%; P < 0.001).

Conclusion

Our data suggests that nuclear and mitochondrial ccf DNA have potential as biomarkers in breast tumor management. However, ccf nDNA shows greater promise regarding sensitivity and specificity.

Levels of plasma circulating cell free nuclear and mitochondrial DNA as potential biomarkers for breast tumors

BACKGROUND

With the aim to simplify cancer management, cancer research lately dedicated itself more and more to discover and develop non-invasive biomarkers. In this connection, circulating cell-free DNA (ccf DNA) seems to be a promising candidate. Altered levels of ccf nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) have been found in several cancer types and might have a diagnostic value.

METHODS

Using multiplex real-time PCR we investigated the levels of ccf nDNA and mtDNA in plasma samples from patients with malignant and benign breast tumors, and from healthy controls. To evaluate the applicability of plasma ccf nDNA and mtDNA as a biomarker for distinguishing between the three study-groups we performed ROC (Receiver Operating Characteristic) curve analysis. We also compared the levels of both species in the cancer group with clinicopathological parameters.

RESULTS

While the levels of ccf nDNA in the cancer group were significantly higher in comparison with the benign tumor group (P < 0.001) and the healthy control group (P < 0.001), the level of ccf mtDNA was found to be significantly lower in the two tumor-groups (benign: P < 0.001; malignant: P = 0.022). The level of ccf nDNA was also associated with tumor-size (<2 cm vs. >2 cm<5 cm; 2250 vs. 6658; Mann-Whitney-U-Test: P = 0.034). Using ROC curve analysis, we were able to distinguish between the breast cancer cases and the healthy controls using ccf nDNA as marker (cut-off: 1866 GE/ml; sensitivity: 81%; specificity: 69%; P < 0.001) and between the tumor group and the healthy controls using ccf mtDNA as marker (cut-off: 463282 GE/ml; sensitivity: 53%; specificity: 87%; P < 0.001).

CONCLUSION

Our data suggests that nuclear and mitochondrial ccf DNA have potential as biomarkers in breast tumor management. However, ccf nDNA shows greater promise regarding sensitivity and specificity.

Markers for Presymptomatic Prediction of Preeclampsia and Intrauterine Growth Restriction

Preeclampsia and intrauterine growth restriction are both characterized by placental malfunction. The pathological processes of abnormal trophoblast invasion, partial absence of maternal spiral artery modification, increased apoptosis of trophoblast cells, and placental ischemia are all associated with the release of specific molecules. These proteins, as well as cell-free fetal DNA and RNA might be detected in the maternal peripheral circulation, quantified, and used for early identification and prediction of preeclampsia and intrauterine growth restriction, prior to the appearance of the clinical symptoms. As preeclampsia and intrauterine growth restriction are associated with increased maternal, perinatal, and neonatal morbidity and mortality, early identification of these pregnancy associated complications will permit the design of appropriate preventive measures. In this review a variety of factors reported to be useful as potential markers for early detection of pregnancies at increased risk will be discussed. Molecules associated with the establishment of the placenta and essential in fetal-maternal interactions, like interleukin 2-receptor, insulinlike growth factor-1, and insulinlike growth factor binding protein-1, placenta growth factor, hepatocyte growth factor, inhibin A, activin A, and human chorionic gonadotrophin seem to be the most likely candidates for presymptomatic markers for preeclampsia and/or intrauterine growth restriction. Detection and discrimination of these molecules through the placental RNA in maternal plasma based strategy has become a realistic option.

Innate immunity turned inside-out: antimicrobial defense by phagocyte extracellular traps

The formation of extracellular traps (ETs) by phagocytic cells has been recognized as a novel and important mechanism of the host innate immune response against infections. ETs are formed by different host immune cells such as neutrophils, mast cells, and eosinophils after stimulation with mitogens, cytokines, or pathogens themselves, in a process dependent upon induction of a reactive-oxygen-species-mediated signaling cascade. ETs consist of nuclear or mitochondrial DNA as a backbone with embedded antimicrobial peptides, histones, and cell-specific proteases and thereby provide a matrix to entrap and kill microbes and to induce the contact system. This review summarizes the latest research on ETs and their role in innate immunity and host innate defense. Attention is also given to mechanisms by which certain leading bacterial pathogens have evolved to avoid entrapment and killing in these specialized structures.

Real-time quantitative polymerase chain reaction measurement of male fetal DNA in maternal plasma

Cell-free fetal DNA can be detected in the blood plasma of pregnant women as early as 5 wk into pregnancy. At present noninvasive prenatal diagnosis has already begun to impact clinical practice. The established applications are for the determination of fetal sex and rhesus D blood group when the mother is rhesus D negative. Both methods are currently evaluated and standardized by a large laboratory network (the Special Non-Invasive Advances in Fetal and Neonatal Evaluation Network, or SAFE) that aims to implement widespread noninvasive prenatal diagnosis throughout the European Union. This chapter presents the basic methodology used in this noninvasive analysis.

Application of maternal plasma DNA analysis for noninvasive prenatal diagnosis of Hb E-beta-thalassemia

To establish simple noninvasive prenatal diagnosis of common beta-thalassemia in Southeast Asia, we have evaluated the possibility of identifying the 3 most common beta-thalassemia genes [beta(E), beta(17A-T), and beta(41/42(-CTCC))] by analysis of fetal DNA in maternal plasma using combined conventional polymerase chain reaction (PCR) and real-time quantitative PCR. Maternal plasma was obtained from peripheral blood of Thai pregnant women collected during the first and second trimesters of gestation. DNA was prepared from 200 microL plasma using a QIAmp Blood Mini Kit. Identifications of the beta(E), beta(41/42(-CTTT)), and beta(17A-T) in plasma DNA were carried out using semi-nested (for beta(E)) and nested (for beta(41/42) and beta(17)) real-time allele-specific PCR methodologies, and the results were compared with those obtained on fetal tissue analysis with routine invasive procedure. Twenty-six fetal beta(E) genes were correctly identified by maternal plasma DNA analysis of 39 pregnant women investigated. The fetal beta(41/42) and beta(17) mutations were detectable in 6 of 12 and 4 of 9 maternal plasma specimens, respectively, which were in concordance with the results obtained by routine invasive procedure. The noninvasive prenatal diagnostic methods developed should potentially prove useful for detection of paternally inherited mutation and for providing the exclusion of pregnancies at risk for this common genetic disorder in the region.

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 disorder.

Quantitative analysis of intact fetal cells in maternal plasma by real-time PCR

OBJECTIVE

Fetal genetic materials in maternal circulation might be potentially used for non-invasive prenatal diagnosis (NIPD). In this study, we quantitatively analysed the intact fetal cells existing in maternal plasma, which would be a special method of NIPD.

STUDY DESIGN

Eleven samples from preeclamptic patients, two samples from patients with RhD incompatibilities, and 30 samples from normal pregnancies as controls were collected. The intact cells in the plasma fraction were separated by centrifugation at high speed. The intact cell pellets were washed with PBS to remove any cell-free DNA.

RESULTS

We were able to detect intact fetal cells in 3 out of 11 preeclamptic plasma samples from women carrying male fetuses, and from both plasma samples of RhD incompatibility affected pregnancies. However, intact fetal cells were not detected in all the 16 normal pregnancies with a male fetus, although cell-free fetal DNA was detected in all these cases.

CONCLUSIONS

Intact fetal cells might be present in maternal plasma. However, the rarity of these cells limits their use for reliable, non-invasive prenatal diagnosis. The detection of such cells was successful in some preeclamptic and RhD incompatibility samples, not in the normal controls. Therefore, as opposed to free fetal DNA in maternal blood the use of intact fetal cells does not provide a reliable mode for NIPD.

Gabor Than Award Lecture 2006: pre-eclampsia and villous trophoblast turnover: perspectives and possibilities

Placental apoptosis is exaggerated in pre-eclampsia and cytotrophoblast proliferation is enhanced. This imbalance may be a primary pathogenic event, whereby excessive syncytiotrophoblast apoptosis counters cytotrophoblast fusion, promoting the liberation of syncytial material which perturbs the maternal vascular endothelium. We have previously shown that primary trophoblasts and explant cultured villous fragments from pre-eclamptic pregnancies elicit greater levels of terminal differentiation and apoptosis. This review considers current opinions in trophoblast cell turnover in normal pregnancy and pre-eclampsia. In the context of other findings, this review highlights: (i) the disparity in expression of pro-apoptotic transcription factor p53 in the syncytiotrophoblast in pre-eclampsia, (ii) the importance of reactive oxygen species and hypoxia in initiating villous trophoblast apoptosis and (iii) the concept that aberrant intervillous haemodynamics, as opposed to oxygen per se, initiates excessive syncytiotrophoblast shedding. Finally, therapeutic ways of restoring the syncytiotrophoblast in pre-eclampsia and preventing excessive placental apoptosis are considered, including a role for mitotic manipulators and growth factor replacement strategies.

Cell-free fetal DNA in maternal plasma and noninvasive prenatal diagnosis

The noninvasive nature of the detection of fetal DNA in the maternal circulation represents the greatest advantage over the conventional methods of prenatal diagnosis. The applications of this methodology involve the detection of the fetal sex, and diagnosis, intra-uterine treatment, and evaluation of the prognosis of many diseases. Fetal cells detected in the maternal circulation have also been shown to be implicated in autoimmune diseases and to represent a potential source of stem cells. On the other hand, with the introduction of a technology that detects the fetal sex as early as at 6-8 weeks of gestation, there is the possibility of early abortion based on sex selection for social purposes. This implies an ethical discussion about the question. The introduction of new noninvasive techniques of prenatal diagnosis and the knowledge of the Nursing Team regarding new methodologies can be of great benefit to the mother and her children, and can help the Genetic Counseling of the families.

Occurrence of neutrophil extracellular DNA traps (NETs) in pre-eclampsia: a link with elevated levels of cell-free DNA?

Manifest pre-eclampsia is associated with activation of peripheral neutrophils as well as elevations in maternal cell-free DNA. For this reason, we were very intrigued by recent reports indicating that activated circulatory neutrophils secrete nuclear DNA to generate extracellular DNA lattices, termed NETs (neutrophil extracellular traps). Our preliminary data indicate that placental syncytiotrophoblast microparticles, which are released in elevated amounts in pre-eclampsia, can induce NETs in isolated neutrophils. Furthermore, we found evidence for the increased presence of NETs directly in the intervillous space of pre-eclamptic placentae. Therefore, these newly discovered entities may be implicated in the underlying etiology of this disorder.

The preterm parturition syndrome

The implicit paradigm that has governed the study and clinical management of preterm labour is that term and preterm parturition are the same processes, except for the gestational age at which they occur. Indeed, both share a common pathway composed of uterine contractility, cervical dilatation and activation of the membranes/decidua. This review explores the concept that while term labour results from physiological activation of the components of the common pathway, preterm labour arises from pathological signalling and activation of one or more components of the common pathway of parturition. The term "great obstetrical syndromes" has been coined to reframe the concept of obstetrical disease. Such syndromes are characterised by: (1) multiple aetiology; (2) long preclinical stage; (3) frequent fetal involvement; (4) clinical manifestations that are often adaptive in nature; and (5) gene-environment interactions that may predispose to the syndromes. This article reviews the evidence indicating that the pathological processes implicated in the preterm parturition syndrome include: (1) intrauterine infection/inflammation; (2) uterine ischaemia; (3) uterine overdistension; (4) abnormal allograft reaction; (5) allergy; (6) cervical insufficiency; and (7) hormonal disorders (progesterone related and corticotrophin-releasing factor related). The implications of this conceptual framework for the prevention, diagnosis, and treatment of preterm labour are discussed.

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 60 years 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 60 years 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 circulation.

Genotyping fetal paternally inherited SNPs by MALDI-TOF MS using cell-free fetal DNA in maternal plasma: Influence of size fractionation

The determination of fetal point mutations from fetal cell-free DNA (cf-DNA) in maternal plasma is technically challenging due to the preponderance of maternal sequences. It has recently been shown that fetal cf-DNA sequences are smaller than maternal ones and that the selection of small cf-DNA fragments by size fractionation by agarose gel electrophoresis leads to the enrichment of fetal cf-DNA sequences, thereby permitting the detection of otherwise masked fetal point mutations. In a separate development, the use of MALDI-TOF MS has also been shown to facilitate the detection of fetal point mutations from cf-DNA in maternal plasma. In this study, a combination of these approaches was examined. cf-DNA was extracted from 18 maternal plasma samples, 10 taken at term and 8 obtained early in the second trimester. A total of 41 SNP loci were examined in size-fractionated and total cf-DNA using either a conventional homogeneous MassEXTEND (hME) assay or a nucleotide-specific single allele base extension reaction (SABER) assay. The analysis of total cf-DNA indicated that size fractionation considerably enhanced the sensitivity of the standard hME assay, especially for samples taken early in pregnancy. Size fractionation also rendered the signals obtained by the SABER assay more precise.

Optimized Real-Time Quantitative PCR Measurement of Male Fetal DNA in Maternal Plasma

DNA of fetal origin is present in the plasma of pregnant women. The quantitative measurement of circulatory fetal DNA (cfDNA) by real-time quantitative PCR (qPCR) has been applied to investigate a possible correlation between increased levels and pregnancy-related disorders. However, as the levels of cfDNA are close to the detection limit (LOD) of the method used, the measurements may not be reliable. This is also problematic for the evaluation of preanalytical steps, such as DNA extraction and cfDNA enrichment by size separation. We optimized a protocol for the qPCR analysis of the multi-copy sequence DYS14 on the Y chromosome. This was compared with an established assay for the single-copy SRY gene. Probit regression analysis showed that the limit of detection (LOD) of the DYS14 assay, (0.4 genome equivalents (GE)) and limit of quantification (LOQ) were 10-fold lower in comparison to SRY (4 GE). The levels of cfDNA obtained from the first trimester of pregnancy could be quantified with high precision by the DYS14 assay (CV below 25%) as opposed to the SRY measurements (26-140%). Additionally, fetal sex was correctly determined in all instances. The low copy numbers of fetal DNA in plasma of women in the first trimester of pregnancy can be measured reliably, targeting the DYS14 that is present in multiple copies per Y chromosome.

Minimal alteration in the ratio of circulatory fetal DNA to fetal corticotropin-releasing hormone mRNA level in preeclampsia

OBJECTIVES

We have recently observed that fetal DNA and fetal corticotropin-releasing hormone (CRH) mRNA are associated with in vitro generated syncytiotrophoblast-derived microparticles, and that the ratio of fetal DNA to mRNA (CRH) varied according to whether the particles were derived by predominantly apoptotic, apo-necrotic or necrotic pathways. Hence, we examined whether these ratios varied in maternal plasma samples taken from normotensive and preeclamptic pregnancies in vivo.

METHODS

Maternal plasma samples were collected from 18 cases with preeclampsia and 29 normotensive term controls. Circulatory fetal CRH mRNA and DNA levels were quantified by real-time PCR and RT-PCR.

RESULTS

Circulatory fetal mRNA and fetal DNA levels were significantly elevated in the preeclampsia study group when compared to normotensive controls. Alterations in the fetal mRNA to DNA ratio between the study and control groups were minimal, even when stratified into early (<34 weeks of gestation) and late (>34 weeks of gestation) onset preeclampsia.

CONCLUSIONS

Our data suggest that although circulatory fetal DNA and mRNA levels are significantly elevated in preeclampsia, the ratios in maternal plasma are not dramatically altered.

Pathophysiology of fetal microchimeric cells

Microchimerism has been defined by the presence of a low number of circulating cells transferred from one individual to another. The transfer of microchimeric cells naturally takes place during pregnancy and occurs bi-directionally between the mother and fetus. Further, microchimerism can also be a result of blood transfusions and organ transplants. Microchimeric cells have been implicated in health and disease. Fetal microchimerism has been correlated with the hyporesponsiveness of the maternal immune system towards a fetal allograft and with the longevity of organ transplants. However, microchimeric cells have been implicated in the pathogenesis of autoimmune diseases including systemic sclerosis. In contrast, microchimeric cells were found to contribute to tissue repair. Much controversy exists around the role of microchimeric cells in the pathogenesis of certain diseases, and these cells in tissues may be a consequence rather than the cause of disease.

Optimized real-time quantitative PCR measurement of male fetal DNA in maternal plasma

BACKGROUND

Circulating fetal DNA (cfDNA) in maternal plasma has been measured to investigate its possible relationship with pregnancy-related disorders, including fetal trisomy 21 and preeclampsia. The circulating concentrations of single-copy fetal genes, however, are close to the detection limits of PCR methods.

METHODS

We optimized a protocol for the real-time quantitative PCR amplification of the multicopy sequence DYS14 on the Y-chromosome. This was compared with an established real-time PCR assay for the single-copy SRY gene.

RESULTS

By probit regression analysis, the measurements of male DNA by the DYS14 assay had a 10-fold lower detection limit (0.4 genome equivalents) than did measurements of SRY. For plasma samples from women in the first trimester of pregnancy, imprecision (CV) was 2%-22% when amplifying DYS14 compared with 26%-140% for SRY.

CONCLUSIONS

The low copy numbers of fetal DNA in plasma of women in the first trimester of pregnancy cannot be measured precisely when targeting single-copy sequences. Better results are obtained by amplifying a sequence that is present in multiple copies per male genome.

Application of fetal DNA detection in maternal plasma: a prenatal diagnosis unit experience

Non-invasive prenatal diagnosis tests based on the analysis of fetal DNA in maternal plasma have potential to be a safer alternative to invasive methods. So far, different studies have shown mainly fetal sex, fetal RhD, and quantitative variations of fetal DNA during gestation with fetal chromosomal anomalies or gestations at risk for preeclampsia. The objective of our research was to evaluate the use of fetal DNA in maternal plasma for clinical application. In our study, we have established the methodology needed for the analysis of fetal DNA. Different methods were used, according to the requirements of the assay. We have used quantitative fluorescent polymerase chain reaction (QF-PCR) to perform fetal sex detection with 90% sensitivity. The same technique permitted the detection of fetal DNA from the 10th week of gestation to hours after delivery. We have successfully carried out the diagnosis of two inherited disorders, cystic fibrosis (conventional PCR and restriction analysis) and Huntington disease (QF-PCR). Ninety percent of the cases studied for fetal RhD by real-time PCR were correctly diagnosed. The detection of fetal DNA sequences is a reality and could reduce the risk of invasive techniques for certain fetal disorders in the near future.

A monoclonal antibody with potential for aiding non-invasive prenatal diagnosis: utility in screening of pregnant women at risk of preeclampsia

The development of a non-invasive method of prenatal diagnosis in maternal blood has been the goal of our investigations during the last years. We have developed several anti-CD71 monoclonal antibodies and optimized a protocol for the isolation of nucleated red blood cells (NRBC) from peripheral maternal blood. The enhanced traffic of fetal erythroblasts into the maternal circulation in preeclampsia has been investigated by several groups. In this study, we compared one of our antibodies, 2F6.3, with a commercial anti-CD71 antibody in blood samples from pregnant women suffering pregnancy-induced hypertension (PIH) and in a control group of pregnant women without clinical features suggestive of an increased risk of developing preeclampsia. The mAb 2F6.3, developed by our group, has succeeded in isolating a significantly higher number of erythroblasts with less maternal cell contamination than the commercial antibody in both women with PIH and in the control group (p<0.01; Wilcoxon Signed Ranks Test). Fluorescence in situ hybridization analysis also demonstrated that 2F6.3 is a better antibody for the isolation of fetal NRBC in maternal blood than the commercial anti-CD71 antibody.