mRNA of placental origin is readily detectable in maternal plasma

Deciphering maternal-fetal cross-talk in the human placenta during parturition using single-cell RNA sequencing

Labor is a complex physiological process requiring a well-orchestrated dialogue between the mother and fetus. However, the cellular contributions and communications that facilitate maternal-fetal cross-talk in labor have not been fully elucidated. Here, single-cell RNA sequencing (scRNA-seq) was applied to decipher maternal-fetal signaling in the human placenta during term labor. First, a single-cell atlas of the human placenta was established, demonstrating that maternal and fetal cell types underwent changes in transcriptomic activity during labor. Cell types most affected by labor were fetal stromal and maternal decidual cells in the chorioamniotic membranes (CAMs) and maternal and fetal myeloid cells in the placenta. Cell-cell interaction analyses showed that CAM and placental cell types participated in labor-driven maternal and fetal signaling, including the collagen, C-X-C motif ligand (CXCL), tumor necrosis factor (TNF), galectin, and interleukin-6 (IL-6) pathways. Integration of scRNA-seq data with publicly available bulk transcriptomic data showed that placenta-derived scRNA-seq signatures could be monitored in the maternal circulation throughout gestation and in labor. Moreover, comparative analysis revealed that placenta-derived signatures in term labor were mirrored by those in spontaneous preterm labor and birth. Furthermore, we demonstrated that early in gestation, labor-specific, placenta-derived signatures could be detected in the circulation of women destined to undergo spontaneous preterm birth, with either intact or prelabor ruptured membranes. Collectively, our findings provide insight into the maternal-fetal cross-talk of human parturition and suggest that placenta-derived single-cell signatures can aid in the development of noninvasive biomarkers for the prediction of preterm birth.

Noninvasive preeclampsia prediction using plasma cell-free RNA signatures

BACKGROUND

Preeclampsia, especially preterm preeclampsia and early-onset preeclampsia, is a life-threating pregnancy disorder, and the heterogeneity and complexity of preeclampsia make it difficult to predict risk and to develop treatments. Plasma cell-free RNA carries unique information from human tissue and may be useful for noninvasive monitoring of maternal, placental, and fetal dynamics during pregnancy.

OBJECTIVE

This study aimed to investigate various RNA biotypes associated with preeclampsia in plasma and to develop classifiers to predict preterm preeclampsia and early-onset preeclampsia before diagnosis.

STUDY DESIGN

We performed a novel, cell-free RNA sequencing method termed polyadenylation ligation-mediated sequencing to investigate the cell-free RNA characteristics of 715 healthy pregnancies and 202 pregnancies affected by preeclampsia before symptom onset. We explored differences in the abundance of different RNA biotypes in plasma between healthy and preeclampsia samples and built preterm preeclampsia and early-onset preeclampsia prediction classifiers using machine learning methods. Furthermore, we validated the performance of the classifiers using the external and internal validation cohorts and assessed the area under the curve and positive predictive value.

RESULTS

We detected 77 genes, including messenger RNA (44%) and microRNA (26%), that were differentially expressed in healthy mothers and mothers with preterm preeclampsia before symptom onset, which could separate participants with preterm preeclampsia from healthy samples and that played critical functional roles in preeclampsia physiology. We developed 2 classifiers for predicting preterm preeclampsia and early-onset preeclampsia before diagnosis based on 13 cell-free RNA signatures and 2 clinical features (in vitro fertilization and mean arterial pressure), respectively. Notably, both classifiers showed enhanced performance when compared with the existing methods. The preterm preeclampsia prediction model achieved 81% area under the curve and 68% positive predictive value in an independent validation cohort (preterm, n=46; control, n=151); the early-onset preeclampsia prediction model had an area under the curve of 88% and a positive predictive value of 73% in an external validation cohort (early-onset preeclampsia, n=28; control, n=234). Furthermore, we demonstrated that downregulation of microRNAs may play vital roles in preeclampsia through the upregulation of preeclampsia-relevant target genes.

CONCLUSION

In this cohort study, a comprehensive transcriptomic landscape of different RNA biotypes in preeclampsia was presented and 2 advanced classifiers with substantial clinical importance for preterm preeclampsia and early-onset preeclampsia prediction before symptom onset were developed. We demonstrated that messenger RNA, microRNA, and long noncoding RNA can simultaneously serve as potential biomarkers of preeclampsia, holding the promise of prevention of preeclampsia in the future. Abnormal cell-free messenger RNA, microRNA, and long noncoding RNA molecular changes may help to elucidate the pathogenic determinants of preeclampsia and open new therapeutic windows to effectively reduce pregnancy complications and fetal morbidity.

Maternal and fetal mitochondrial gene dysregulation in hypertensive disorders of pregnancy

Mitochondrial dysfunction has been implicated in pregnancy-induced hypertension (PIH). The role of mitochondrial gene dysregulation in PIH, and consequences for maternal-fetal interactions, remain elusive. Here, we investigated mitochondrial gene expression and dysregulation in maternal and placental tissues from pregnancies with and without PIH; further, we measured circulating mitochondrial DNA (mtDNA) mutational load, an index of mtDNA integrity. Differential gene expression analysis followed by Time Course Gene Set Analysis (TcGSA) was conducted on publicly available high throughput sequencing transcriptomic data sets. Mutational load analysis was carried out on peripheral mononuclear blood cells from healthy pregnant individuals and individuals with preeclampsia. Thirty mitochondrial differentially expressed genes (mtDEGs) were detected in the maternal cell-free circulating transcriptome, whereas nine were detected in placental transcriptome from pregnancies with PIH. In PIH pregnancies, maternal mitochondrial dysregulation was associated with pathways involved in inflammation, cell death/survival, and placental development, whereas fetal mitochondrial dysregulation was associated with increased production of extracellular vesicles (EVs) at term. Mothers with preeclampsia did not exhibit a significantly different degree of mtDNA mutational load. Our findings support the involvement of maternal mitochondrial dysregulation in the pathophysiology of PIH and suggest that mitochondria may mediate maternal-fetal interactions during healthy pregnancy.NEW & NOTEWORTHY This study identifies aberrant maternal and fetal expression of mitochondrial genes in pregnancies with gestational hypertension and preeclampsia. Mitochondrial gene dysregulation may be a common etiological factor contributing to the development of de novo hypertension in pregnancy-associated hypertensive disorders.

Establishment of the fetal-maternal interface: developmental events in human implantation and placentation

Early pregnancy is a complex and well-orchestrated differentiation process that involves all the cellular elements of the fetal-maternal interface. Aberrant trophoblast-decidual interactions can lead to miscarriage and disorders that occur later in pregnancy, including preeclampsia, intrauterine fetal growth restriction, and preterm labor. A great deal of research on the regulation of implantation and placentation has been performed in a wide range of species. However, there is significant species variation regarding trophoblast differentiation as well as decidual-specific gene expression and regulation. Most of the relevant information has been obtained from studies using mouse models. A comprehensive understanding of the physiology and pathology of human implantation and placentation has only recently been obtained because of emerging advanced technologies. With the derivation of human trophoblast stem cells, 3D-organoid cultures, and single-cell analyses of differentiated cells, cell type-specific transcript profiles and functions were generated, and each exhibited a unique signature. Additionally, through integrative transcriptomic information, researchers can uncover the cellular dysfunction of embryonic and placental cells in peri-implantation embryos and the early pathological placenta. In fact, the clinical utility of fetal-maternal cellular trafficking has been applied for the noninvasive prenatal diagnosis of aneuploidies and the prediction of pregnancy complications. Furthermore, recent studies have proposed a viable path toward the development of therapeutic strategies targeting placenta-enriched molecules for placental dysfunction and diseases.

Placenta-Derived Extracellular Vesicles in Pregnancy Complications and Prospects on a Liquid Biopsy for Hemoglobin Bart's Disease

Extracellular vesicles (EVs) are nano-scaled vesicles released from all cell types into extracellular fluids and specifically contain signature molecules of the original cells and tissues, including the placenta. Placenta-derived EVs can be detected in maternal circulation at as early as six weeks of gestation, and their release can be triggered by the oxygen level and glucose concentration. Placental-associated complications such as preeclampsia, fetal growth restriction, and gestational diabetes have alterations in placenta-derived EVs in maternal plasma, and this can be used as a liquid biopsy for the diagnosis, prediction, and monitoring of such pregnancy complications. Alpha-thalassemia major ("homozygous alpha-thalassemia-1") or hemoglobin Bart's disease is the most severe form of thalassemia disease, and this condition is lethal for the fetus. Women with Bart's hydrops fetalis demonstrate signs of placental hypoxia and placentomegaly, thereby placenta-derived EVs provide an opportunity for a non-invasive liquid biopsy of this lethal condition. In this article, we introduced clinical features and current diagnostic markers of Bart's hydrops fetalis, extensively summarize the characteristics and biology of placenta-derived EVs, and discuss the challenges and opportunities of placenta-derived EVs as part of diagnostic tests for placental complications focusing on Bart's hydrop fetalis.

Reappraisal of evolving methods in non-invasive prenatal screening: Discovery, biology and clinical utility

Non-invasive prenatal screening (NIPS) offers an opportunity to screen or determine features associated with the fetus. Earlier, prenatal testing was done with cytogenetic procedures like karyotyping or fluorescence in-situ hybridization, which necessitated invasive methods such as fetal blood sampling, chorionic villus sampling or amniocentesis. Over the last two decades, there has been a paradigm shift away from invasive prenatal diagnostic methods to non-invasive ones. NIPS tests heavily rely on cell-free fetal DNA (cffDNA). This DNA is released into the maternal circulation by placenta. Like cffDNA, fetal cells such as nucleated red blood cells, placental trophoblasts, leukocytes, and exosomes or fetal RNA circulating in maternal plasma, have enormous potential in non-invasive prenatal testing, but their use is still limited due to a number of limitations. Non-invasive approaches currently use circulating fetal DNA to assess the fetal genetic milieu. Methods with an acceptable detection rate and specificity such as sequencing, methylation, or PCR, have recently gained popularity in NIPS. Now that NIPS has established clinical significance in prenatal screening and diagnosis, it is critical to gain insights into and comprehend the genesis of NIPS de novo. The current review reappraises the development and emergence of non-invasive prenatal screen/test approaches, as well as their clinical application, with a focus, on the scope, benefits, and limitations.

Addressing ethical issues related to prenatal diagnostic procedures

BACKGROUND

For women of advanced maternal age or couples with high risk of genetic mutations, the ability to screen for embryos free of certain genetic mutations is reassuring, as it provides opportunity to address age-related decline in fertility through preimplantation genetic testing. This procedure has potential to facilitate better embryo selection, improve implantation rates with single embryo transfer and reduce miscarriage rates, among others, yet confers some risk to the embryo and additional costs of assisted reproductive technology. This raises questions whether, when and which patients should receive routine PGT-A prior to embryo transfer.

DISCUSSION

Prenatal diagnostic procedures refer to tests done when one or both genetic parents has a known genetic disorder (or has worries about the disorder) and testing is performed on them, their gametes or on the embryos to determine if the latter is likely to carry a genetic disorder. PGT is used to identify genetic defects in gametes or embryos (often created through in vitro fertilization (IVF). The procedures generate immense potential to improve health and wellbeing by preventing conception or birth of babies with undesirable traits, life-limiting conditions and even lethal conditions. However, they generate a lot of information, which often may challenge decision-making ability of healthcare providers and parents, and raise ethical challenges.

CONCLUSION

Prenatal diagnostic procedures have potential to address uncertainty and risk of having a child affected with a genetic disease. They, however, often raise own uncertainty and controversies, whose origin, manifestation and related ethical issues are presented. There is need to develop individual and couple decision support tools that incorporate patients' values and concerns in the decision-making process in order to promote more informed decisions, during counseling.

Circulating Non-coding RNAs and Exosomes: Liquid Biopsies for Monitoring Preeclampsia

Preeclampsia (PE) remains a leading cause of maternal and fetal mortality, due to ineffective treatment and diagnostic strategies, compounded by the lack of clarity on the etiology of the disorder. The early prediction or accurate diagnosis of PE is a concern of researchers. Liquid biopsy can be analyzed for cell-free nucleic acids and exosomes. Because circulating non-coding RNAs (ncRNAs) and peripheral blood exosomes can be detected in the peripheral blood of women in early pregnancy, these vesicles and their contents have become the focus of research on early predictive and diagnostic biomarkers for preeclampsia. In this review, we focus on recent studies addressing the roles of circulating ncRNAs and exosomes in PE, with particular attention paid to the potential application value of placenta-derived exosomes and circulating ncRNAs as PE-specific biomarkers.

[Latest Research Findings on Prediction of Preeclampsia in Pregnant Women Based on Analysis of Cell-Free RNA in Peripheral Blood]

Preeclampsia gravely threatens the health of mothers and infants. At present, treatment based on the relevant mechanisms of pathogenesis is still not available, and there is no independent reliable clinical index for early prediction of preeclampsia. According to recent studies, analysis of the cell-free RNA in the peripheral blood of pregnant women has shown that testing certain cell-free RNA levels can help predict in advance the occurrence of preeclampsia before clinical symptoms appear. In this paper, we described the status of research and progress in using maternal cell-free RNA analysis in predicting preeclampsia. In addition, we stated that cell-free RNA in peripheral blood may become a promising, real-time and non-invasive monitoring method that can be used to explore the mechanisms of pathogenesis and pathophysiology of preeclampsia and to identify different subtypes of preeclampsia.

Single-Cell Immunobiology of the Maternal-Fetal Interface

Pregnancy success requires constant dialogue between the mother and developing conceptus. Such crosstalk is facilitated through complex interactions between maternal and fetal cells at distinct tissue sites, collectively termed the "maternal-fetal interface." The emergence of single-cell technologies has enabled a deeper understanding of the unique processes taking place at the maternal-fetal interface as well as the discovery of novel pathways and immune and nonimmune cell types. Single-cell approaches have also been applied to decipher the cellular dynamics throughout pregnancy, in parturition, and in obstetrical syndromes such as recurrent spontaneous abortion, preeclampsia, and preterm labor. Furthermore, single-cell technologies have been used during the recent COVID-19 pandemic to evaluate placental viral cell entry and the impact of SARS-CoV-2 infection on maternal and fetal immunity. In this brief review, we summarize the current knowledge of cellular immunobiology in pregnancy and its complications that has been generated through single-cell investigations of the maternal-fetal interface.

Study on the Clinical Value of Noninvasive Prenatal Testing in Screening the Chromosomal Abnormalities of the Fetus in the Elderly Pregnant Women

Introduction

To explore the clinical value of noninvasive prenatal testing (NIPT) in screening the chromosomal abnormalities of the fetus in the elderly pregnant women.

Materials and Methods

Between January 2020 and December 2021, 1949 elderly pregnant women underwent NIPT in our hospital. At the same time, 236 elderly pregnant women received invasive prenatal diagnosis, and the pregnancy outcomes were followed-up.

Results

When NIPT was used for prenatal screening of fetal chromosomal aneuploidy, its diagnostic coincidence rate for trisomy 21 was the highest, with a coincidence rate of 90.00%, and the diagnostic coincidence rate for other chromosomal abnormalities was the lowest, only 22.22%. The sensitivity, specificity, positive predictive rate, and negative predictive rate for T21 by NIPT were 100%, 99.97%, 94.28%, and 100%; for T18 were 100%, 99.92%, 72.22%, and 100%, respectively; and for T13 were 100%, 99.95%, 50%, and 100%, respectively. Patients with high risks according to NIPT results further received invasive prenatal diagnosis, and 18 cases were excluded from the follow-up. For the remaining 1933 cases in the NIPT group, there was an incidence of 2.28% of adverse pregnancy outcomes. For the remaining 234 cases in the Amniocentesis group, there was an incidence of 1.28% of adverse pregnancy outcomes. There was no significant difference between the two groups (P > 0.05). The diagnostic rate of fetal chromosomal abnormalities in pregnant women under 40 years old was about 0.39-0.79%; however, the risk for people over 40 is relatively high at 1.32-4.44%.

Conclusion

The noninvasive prenatal screening of fetal DNA in the second trimester of pregnancy for elderly pregnant women has high application value in the prediction of pregnancy outcome. The high risk of pregnancy can be determined by detecting trisomy 21, 18, and 13 syndromes, and the probability of adverse pregnancy outcome increases.

Trophectoderm Transcriptome Analysis in LIN28 Knockdown Ovine Conceptuses Suggests Diverse Roles of the LIN28-let-7 Axis in Placental and Fetal Development

The proper conceptus elongation in ruminants is critical for the successful placentation and establishment of pregnancy. We have previously shown that the trophectoderm-specific knockdown of LIN28A/B in day 9 ovine blastocysts resulted in increased let-7 miRNAs and reduced conceptus elongation at day 16 of gestation. In this current study, by transcriptome analysis of LIN28A knockdown (AKD) or LIN28B knockdown (BKD) trophectoderm (TE), we explored the downstream target genes of the LIN28-let-7 axis and their roles in the placental and fetal development. We identified 449 differentially expressed genes (DEGs) in AKD TE and 1214 DEGs in BKD TE compared to non-targeting control (NTC). Our analysis further revealed that 210 downregulated genes in AKD TE and 562 downregulated genes in BKD TE were the potential targets of let-7 miRNAs. Moreover, 16 downregulated genes in AKD TE and 57 downregulated and 7 upregulated genes in BKD TE were transcription factors. The DEGs in AKD and BKD TE showed enrichment in the biological processes and pathways critical for placental development and function, and fetal development and growth. The results of this study suggest the potential roles of the LIN28-let-7 axis in placental and fetal development beyond its involvement in trophoblast proliferation and conceptus elongation.

The Role of MiRNA in Cancer: Pathogenesis, Diagnosis, and Treatment

Cancer is also determined by the alterations of oncogenes and tumor suppressor genes. These gene expressions can be regulated by microRNAs (miRNA). At this point, researchers focus on addressing two main questions: "How are oncogenes and/or tumor suppressor genes regulated by miRNAs?" and "Which other mechanisms in cancer cells are regulated by miRNAs?" In this work we focus on gathering the publications answering these questions. The expression of miRNAs is affected by amplification, deletion or mutation. These processes are controlled by oncogenes and tumor suppressor genes, which regulate different mechanisms of cancer initiation and progression including cell proliferation, cell growth, apoptosis, DNA repair, invasion, angiogenesis, metastasis, drug resistance, metabolic regulation, and immune response regulation in cancer cells. In addition, profiling of miRNA is an important step in developing a new therapeutic approach for cancer.

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.

Fetomaternal microchimerism and genetic diagnosis: On the origins of fetal cells and cell-free fetal DNA in the pregnant woman

During pregnancy several types of fetal cells and fetal stem cells, including pregnancy-associated progenitor cells (PAPCs), traffic into the maternal circulation. Whereas they also migrate to various maternal organs and adopt the phenotype of the target tissues to contribute to regenerative processes, fetal cells also play a role in the pathogenesis of maternal diseases. In addition, cell-free fetal DNA (cffDNA) is detectable in the plasma of pregnant women. Together they constitute the well-known phenomenon of fetomaternal microchimerism, which inspired the concept of non-invasive prenatal testing (NIPT) using maternal blood. An in-depth knowledge concerning the origins of these fetal cells and cffDNA allows a more comprehensive understanding of the biological relevance of fetomaternal microchimerism and has implications for the ongoing expansion of resultant clinical applications.

Function Follows Form: Gene Expression and Prenatal Screening

To date, prenatal testing has relied on imaging to determine fetal 'form' (anatomy). 'Function', as ascertained by measuring fetal or placental mRNA transcripts in maternal blood, has the potential to more precisely determine which pregnancies need closer monitoring and which babies should be delivered in special care settings.

Epigenetics, fragmentomics, and topology of cell-free DNA in liquid biopsies

Liquid biopsies that analyze cell-free DNA in blood plasma are used for noninvasive prenatal testing, oncology, and monitoring of organ transplant recipients. DNA molecules are released into the plasma from various bodily tissues. Physical and molecular features of cell-free DNA fragments and their distribution over the genome bear information about their tissues of origin. Moreover, patterns of DNA methylation of these molecules reflect those of their tissue sources. The nucleosomal organization and nuclease content of the tissue of origin affect the fragmentation profile of plasma DNA molecules, such as fragment size and end motifs. Besides double-stranded linear fragments, other topological forms of cell-free DNA also exist-namely circular and single-stranded molecules. Enhanced by these features, liquid biopsies hold promise for the noninvasive detection of tissue-specific pathologies with a range of clinical applications.

Cell-free DNA and RNA-measurement and applications in clinical diagnostics with focus on metabolic disorders

Circulating cell-free DNA (cfDNA) and RNA (cfRNA) hold enormous potential as a new class of biomarkers for the development of noninvasive liquid biopsies in many diseases and conditions. In recent years, cfDNA and cfRNA have been studied intensely as tools for noninvasive prenatal testing, solid organ transplantation, cancer screening, and monitoring of tumors. In obesity, higher cfDNA concentration indicates accelerated cellular turnover of adipocytes during expansion of adipose mass and may be directly involved in the development of adipose tissue insulin resistance by inducing inflammation. Furthermore, cfDNA and cfRNA have promising diagnostic value in a range of obesity-related metabolic disorders, such as nonalcoholic fatty liver disease, type 2 diabetes, and diabetic complications. Here, we review the current and future applications of cfDNA and cfRNA within clinical diagnostics, discuss technical and analytical challenges in the field, and summarize the opportunities of using cfDNA and cfRNA in the diagnostics and prognostics of obesity-related metabolic disorders.

A clinically validated human capillary blood transcriptome test for global systems biology studies

To prevent and treat chronic diseases, including cancer, a global application of systems biology is needed. We report here a whole blood transcriptome test that needs only 50 μl of capillary (fingerprick) blood. This test is suitable for global applications because the samples are preserved at ambient temperature for up to 4 weeks and the RNA preservative inactivates all pathogens, enabling safe transportation. Both the laboratory and bioinformatic steps are automated and performed in a clinical lab, which minimizes batch effects and creates unbiased datasets. Given its clinical testing performance and accessibility to traditionally underrepresented and diverse populations, this test offers a unique ability to reveal molecular mechanisms of disease and enable longitudinal, population-scale studies.

Discovery and Verification of Extracellular miRNA Biomarkers for Non-invasive Prediction of Pre-eclampsia in Asymptomatic Women

Development of effective prevention and treatment strategies for pre-eclampsia is limited by the lack of accurate methods for identification of at-risk pregnancies. We performed small RNA sequencing (RNA-seq) of maternal serum extracellular RNAs (exRNAs) to discover and verify microRNAs (miRNAs) differentially expressed in patients who later developed pre-eclampsia. Sera collected from 73 pre-eclampsia cases and 139 controls between 17 and 28 weeks gestational age (GA), divided into separate discovery and verification cohorts, are analyzed by small RNA-seq. Discovery and verification of univariate and bivariate miRNA biomarkers reveal that bivariate biomarkers verify at a markedly higher rate than univariate biomarkers. The majority of verified biomarkers contain miR-155-5p, which has been reported to mediate the pre-eclampsia-associated repression of endothelial nitric oxide synthase (eNOS) by tumor necrosis factor alpha (TNF-α). Deconvolution analysis reveals that several verified miRNA biomarkers come from the placenta and are likely carried by placenta-specific extracellular vesicles.

Small RNA-seq of maternal serum in women who later developed pre-eclampsia

Bioinformatic analyses identify univariate and bivariate miRNA biomarkers

Many bivariate biomarkers contain miR-155-5p

Deconvolution analyses verify several miRNAs to be placenta specific

Investigating Pregnancy and Its Complications Using Circulating Cell-Free RNA in Women's Blood During Gestation

In recent years, there have been major advances in the application of non-invasive techniques to predict pregnancy-related complications, for example by measuring cell-free RNA (cfRNA) in maternal blood. In contrast to cell-free DNA (cfDNA), which is already in clinical use to diagnose fetal aneuploidy, circulating RNA levels can correspond with tissue-specific gene expression and provide a snapshot of prenatal health across gestation. Here, we review the physiologic origins of cfRNA and its novel applications and corresponding challenges to monitor fetal and maternal health and predict pregnancy-related complications.

The 100 most-cited articles on prenatal diagnosis: A bibliometric analysis

BACKGROUND

The number of citations a published article receives can be used to demonstrate its impact on a field of study. The objective of this study was to identify and characterize the 100 most-cited research articles (T100) published on prenatal diagnosis.

METHODS

The Web of Science (WOS) database was searched for papers on prenatal diagnosis published between 1900 and 2018. The 100 most-cited original articles and reviews were recorded. Each eligible paper was reviewed for authors, journal name, year of publication, country, institution, total citations, citation density, H-index, research field, article type, and keywords.

RESULTS

The T100 were published between 1972 and 2015 with a mean of 332.7 citations per paper (range: 196-1254). Most of the T100 were published between 1990 and 2005, in 35 journals led by New England Journal of Medicine (n = 14) followed by Lancet (n = 10), and Proceedings of The National Academy of Sciences of the United States of America (n = 8). Studies on method application, which promotes field development, were the majority article type. The team of Lo YM featured prominently in the field, and the United States of America, United Kingdom, and Hong Kong, China were the leading countries/regions. Frequency of cooperation was also highest among these 3 regions. Hierarchical cluster analysis produced 4 groups of keywords.

CONCLUSION

Our analysis provides a historical perspective on scientific progress in prenatal diagnosis and may assist clinicians and researchers in assessing the quality of research over the past 50 years. It also provides concise information to guide future research.

Current and future perspectives of liquid biopsies in genomics-driven oncology

Precision oncology seeks to leverage molecular information about cancer to improve patient outcomes. Tissue biopsy samples are widely used to characterize tumours but are limited by constraints on sampling frequency and their incomplete representation of the entire tumour bulk. Now, attention is turning to minimally invasive liquid biopsies, which enable analysis of tumour components (including circulating tumour cells and circulating tumour DNA) in bodily fluids such as blood. The potential of liquid biopsies is highlighted by studies that show they can track the evolutionary dynamics and heterogeneity of tumours and can detect very early emergence of therapy resistance, residual disease and recurrence. However, the analytical validity and clinical utility of liquid biopsies must be rigorously demonstrated before this potential can be realized.

Human placental lactogen mRNA in maternal plasma play a role in prenatal diagnosis of abnormally invasive placenta: yes or no?

Objective: To determine whether maternal plasma human placental lactogen (hPL) mRNA levels can predict abnormally invasive placenta. Study design: Sixty-eight singleton pregnant women with prior Cesarean deliveries were classified into three groups: 35 with normal placentation (control group); 21 with placenta previa alone (placenta previa group); 12 with placenta previa and placenta accreta (placenta accreta group). Maternal plasma hPL mRNA concentrations were measured by real-time reverse-transcription polymerase chain reaction Result: The multiple of the median (median, range) for hPL mRNA was significantly higher for the placenta accreta group (2.78, 1.09-4.56) than the control (1.00, 0.29-2.98) or placenta previa (1.12, 0.33-3.25) groups (Steel-Dwass test, p < .001 and p = .005, respectively), was not significantly different between the women with placenta accreta who underwent hysterectomies (2.96, 1.38-4.56) and the women whose deliveries did not result in hysterectomy (2.36, 1.09-3.25) in the placenta accreta group (Mann-Whitney U test, p = .372). Conclusion: hPL mRNA in maternal plasma may indicate abnormally invasive placenta but cannot predict whether abnormally invasive placenta will result in hysterectomy.

The untapped potential of placenta-enriched molecules for diagnostic and therapeutic development

Pregnancy complications such as fetal growth restriction and preeclampsia are diseases with limited biomarkers for prediction, and a complete lack of therapeutic options. We define placenta-enriched molecules as those that are highly expressed in the placenta relative to all other human tissues. Many exist including mRNAs, miRNAs and proteins. It is now well established that placenta-enriched mRNAs are found within the maternal circulation and are cleared rapidly after birth. Similarly, distinct clusters of miRNAs that are placenta-enriched have been identified and are measurable within the circulation. However, perhaps the most established potential diagnostics thus far are circulating placental proteins such as placental growth factor (PlGF), pregnancy associated pregnancy protein-A (PAPP-A) and soluble FMS-like tyrosine kinase 1 (sFlt-1). There has also been much interest in targeting placenta-enriched molecules as a means to treat diseases of pregnancy. We have shown promising results in targeting placenta-enriched epidermal growth factor receptor (EGFR) to treat ectopic pregnancy. Others have focused on using placenta-enriched molecules as a means of homing therapeutic-filled nanoparticles to the placenta, or to directly target sFlt-1 to improve disease outcomes. Importantly, many placenta-enriched molecules remain largely unstudied. We propose that a better understanding of their biology, and potential contribution to the pathogenesis of diseases, may yield more predictive diagnostic and therapeutic targets.

Comprehensive Analysis of Gene Expression Profiles and DNA Methylome reveals Oas1, Ppie, Polr2g as Pathogenic Target Genes of Gestational Diabetes Mellitus

Gestational Diabetes Mellitus (GDM) has a high incidence of pregnancy, which seriously affects the life quality of pregnant women and fetal health. DNA methylation is one of the most important epigenetic modification that can regulate the gene expression level, and thus affect the occurrence of various diseases. Increasing evidence has shown that gene expression changes caused by DNA methylation play an important role in metabolic diseases. Here we explored the mechanisms and biological processes that affect the occurrence and development of GDM through analyzing the gene expression profiles and DNA methylation data of GDM. We detected 24,577 differential CpG sites mapping to 9339 genes (DMGs, differential methylation gene) and 931 differential expressed genes (DEGs) between normal samples and GDM samples. GO (gene ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis of 326 overlapping genes between DMGs and DEGs showed obvious enrichment in terms related to metabolic disorders and immune responses. We identified Oas1, Ppie, Polr2g as possible pathogenic target genes of GDM by combining protein-protein interaction analysis. Our study provides possible targets for early diagnosis of GDM and information for clinical prevention of abnormal fetal development and type 2 diabetes.

Comparative expression patterns of selected membrane transporters in differentiated BeWo and human primary trophoblast cells

Although placental membrane transporters have an important impact on materno-fetal nutrient transfer, placental cell models are poorly characterized regarding transporter expression. We assessed the mRNA expression of 26 physiologically important solute carriers and ABC transporters in BeWo (b30 clone) and primary human trophoblast cells (PHT) before and after syncytialization. 77% of the transporters showed similar mRNA expression changes between BeWo and PHT after syncytialization. Selected transporters, however, were either lacking in BeWo or showed different trends after syncytialization. In conclusion, BeWo cells generally represent an apt model for transporter studies, but their suitability should be confirmed for each transporter by comparison with PHT.

Noninvasively diagnosing for fetal trisomy 21 by examining heterozygous single nucleotide polymorphisms in the placental specific genes on chromosome 21

OBJECTIVE

Noninvasive prenatal diagnosing for fetal trisomy 21 could help to avoid unnecessary amniocentesis. It is feasible to target the cell-free placental-specific mRNA in maternal plasma, thus eliminating the interference from the maternal genetic background.

STUDY DESIGN

In this study, placental-specific genes on chromosome 21 were identified by searching the TiGER database and reviewing the published literature. These cell-free placental-specific mRNA fragments in maternal plasma were amplified and sequenced. Then, the allelic ratio of heterozygous single-nucleotide polymorphisms(SNPs) was analyzed.

RESULTS

Four placental-specific genes (DNMT3L, KRTAP26-1, PLAC4, DSCR4) were identified. This study included 42 cases of normal pregnancies and 19 cases of trisomy 21 pregnancies. The probability density function showed that the allelic ratio of heterozygous SNPs in normal pregnancy reached a peak at 1.0, and that in the trisomy 21 pregnancy was a double-peaked curve in both 0.5 and 2.0. However, the allelic ratio of heterozygous SNPs demonstrated no statistical difference between the normal and trisomy 21 pregnancies.

CONCLUSION

Fetal trisomy 21 could not be diagnosed by examining the heterozygous SNPs of cell-free placental-specific mRNA on chromosome 21. This might be because the low quantity and quality of cell-free placental-specific mRNA fragments in maternal plasma, and the limited available heterozygous SNPs on the placental-specific genes.

Novel Insights into Concepts and Directionality of Maternal⁻Fetal Cholesterol Transfer across the Human Placenta

Cholesterol is indispensable for cellular membrane composition and function. It is also a precursor for the synthesis of steroid hormones, which promote, among others, the maturation of fetal organs. A role of the ATP-binding-cassette-transporter-A1 (ABCA1) in the transport of maternal cholesterol to the fetus was suggested by transferring cholesterol to apolipoprotein-A-1 (apo-A1), but the directionality of the apoA-1/ABCA1-dependent cholesterol transport remains unclear. We isolated primary trophoblasts from term placentae to test the hypotheses that (1) apoA-1/ABCA1 dispatches cholesterol mainly towards the fetus to support fetal developmental maturation at term, and (2) differentiated syncytiotrophoblasts (STB) exert higher cholesterol transport activity than undifferentiated cytotrophoblasts (CTB). As experimental models, we used (1) trophoblast monolayers grown on Transwell^® system consisting of apical (maternal-like) and basal (fetal-like) compartments, and (2) trophoblasts grown on conventional culture plates at CTB and STB stages. Surprisingly, apoA-1-mediated cholesterol efflux operated almost exclusively at the apical-maternal side, where ABCA1 was also localized by immunofluorescence. We found greater cholesterol efflux capacity in STB, which was increased by liver-X-receptor agonist treatment and decreased by ABCA1 inhibition. We conclude that at term the apoA-1/ABCA1 pathway is rather involved in cholesterol transport to the mother than in transfer to the fully developed fetus.

Integrated analysis of long noncoding RNA expression profiles in lymph node metastasis of hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, and metastasis of HCC is the leading cause of poor prognosis. Among all the extrahepatic metastases, lymph node metastasis (LNM) is common, second only to lung metastasis. However, the pathogenesis of HCC LNM remains largely unknown.

METHODS

Microarray was performed to investigate the long noncoding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in serum samples from HCC LNM patients (N = 4) and HCC non-LNM controls (N = 5). Subsequently, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was applied to validate the expression levels of randomly selected differential lncRNAs and mRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were employed to explore the potential functions of differentially expressed mRNAs. Co-expression networks were further constructed to elucidate the interactions of the differential genes and to speculate on the potential functions of the dominant lncRNAs. In this research, we attempted to illuminate the correlations between lncRNA and HCC LNM.

RESULTS

Compared with the non-LNM group, a total of 234 lncRNAs and 58 mRNAs were obtained as significantly dysregulated genes in LNM group (p < 0.05, fold change ≥ 2). Functional enrichment analyses showed that upregulated mRNAs are mostly enriched for glucose-6-phosphate dehydrogenase activity, biotin binding and AP-3 adaptor complex, while the downregulated mRNAs are enriched for macrophage colony-stimulating factor receptor binding, succinate-CoA ligase activity and palmitoyltransferase activity. In addition, coexpression network revealed that the dominant lncRNAs are potential participants of protein metabolic process, integral component of membrane, RNA binding, Golgi apparatus, as well as focal adhesion pathway.

CONCLUSION

This study first revealed the expression profiles and potential functions of dysregulated lncRNAs and mRNAs in HCC LNM, which may provide novel clues for further studies on HCC LNM.

Placenta Accreta Spectrum: A Review of Pathology, Molecular Biology, and Biomarkers

Background. Placenta accreta spectrum (PAS) is a condition of abnormal placental invasion encompassing placenta accreta, increta, and percreta and is a major cause of severe maternal morbidity and mortality. The diagnosis of a PAS is made on the basis of histopathologic examination and characterised by an absence of decidua and chorionic villi are seen to directly adjacent to myometrial fibres. The underlying molecular biology of PAS is a complex process that requires further research; for ease, we have divided these processes into angiogenesis, proliferation, and inflammation/invasion. A number of diagnostic serum biomarkers have been investigated in PAS, including human chorionic gonadotropin (HCG), pregnancy-associated plasma protein-A (PAPP-A), and alpha-fetoprotein (AFP). They have shown variable reliability and variability of measurement depending on gestational age at sampling. At present, a sensitive serum biomarker for invasive placentation remains elusive. In summary, there are a limited number of studies that have contributed to our understanding of the molecular biology of PAS, and additional biomarkers are needed to aid diagnosis and disease stratification.

MeDIP combined with in-solution targeted enrichment followed by NGS: Inter-individual methylation variability of fetal-specific biomarkers and their implementation in a proof of concept study for NIPT

DNA methylation is the most characterized epigenetic process exhibiting stochastic variation across different tissues and individuals. In non-invasive prenatal testing (NIPT) fetal specific methylated regions can potentially be used as biomarkers for the accurate detection of fetal aneuploidies. The aim of this study was the investigation of inter-individual methylation variability of previously reported fetal-specific markers and their implementation towards the development of a novel NIPT assay for the detection of trisomies 13, 18, and 21. Methylated DNA Immunoprecipitation (MeDIP) combined with in-solution targeted enrichment followed by NGS was performed in 29 CVS and 27 female plasma samples to assess inter-individual methylation variability of 331 fetal-specific differentially methylated regions (DMRs). The same approach was implemented for the NIPT of trisomies 13, 18 and 21 using spiked-in (n = 6) and pregnancy samples (n = 44), including one trisomy 13, one trisomy 18 and four trisomy 21. Despite the variability of DMRs, CVS samples showed statistically significant hypermethylation (p<2e-16) compared to plasma samples. Importantly, our assay correctly classified all euploid and aneuploid cases without any false positive results (n = 44). This work provides the starting point for the development of a NIPT assay based on a robust set of fetal specific biomarkers for the detection of fetal aneuploidies. Furthermore, the assay’s targeted nature significantly reduces the analysis cost per sample while providing high read depth at regions of interest increasing significantly its accuracy.

Liquid biopsies: DNA methylation analyses in circulating cell-free DNA

Analysis of patient's materials like cells or nucleic acids obtained in a minimally invasive or noninvasive manner through the sampling of blood or other body fluids serves as liquid biopsies, which has huge potential for numerous diagnostic applications. Circulating cell-free DNA (cfDNA) is explored as a prognostic or predictive marker of liquid biopsies with the improvements in genomic and molecular methods. DNA methylation is an important epigenetic marker known to affect gene expression. cfDNA methylation detection is a very promising approach as abnormal distribution of DNA methylation is one of the hallmarks of many cancers and methylation changes occur early during carcinogenesis. This review summarizes the various investigational applications of cfDNA methylation and its oxidized derivatives as biomarkers for cancer diagnosis, prenatal diagnosis and organ transplantation monitoring. The review also provides a brief overview of the technologies for cfDNA methylation analysis based on next generation sequencing.

Placental exosomes profile in maternal and fetal circulation in intrauterine growth restriction - Liquid biopsies to monitoring fetal growth

INTRODUCTION

Placenta-derived exosomes may represent an additional pathway by which the placenta communicates with the maternal system to induce maternal vascular adaptations to pregnancy and it may be affected during Fetal growth restriction (FGR). The objective of this study was to quantify the concentration of total and placenta-derived exosomes in maternal and fetal circulation in small fetuses classified as FGR or small for gestational age (SGA).

METHODS

Prospective cohort study in singleton term gestations including 10 normally grown fetuses and 20 small fetuses, sub-classified into SGA and FGR accordingly to birth weight (BW) percentile and fetoplacental Doppler. Exosomes were isolated from maternal and fetal plasma and characterized by morphology, enrichment of exosomal proteins, and size distribution by electron microscopy, western blot, and nanoparticle tracking analysis, respectively. Total and specific placenta-derived exosomes were determined using quantum dots coupled with CD63^+ve and placental-type alkaline phosphatase (PLAP)^+ve antibodies, respectively.

RESULTS

Maternal concentrations of CD63^+ve and PLAP^+ve exosomes were similar between the groups (all p > 0.05). However, there was a significant positive correlation between the ratio of placental-derived to total exosomes (PLAP^+ve ratio) and BW percentile, [rho = 0.77 (95% CI: 0.57 to 0.89); p = 0.0001]. The contribution of placental exosomes to the total exosome concentration in maternal and fetal circulation showed a significant decrease among cases, with lower PLAP^+ve ratios in FGR compared to controls and SGA cases.

DISCUSSION

Quantification of placental exosomes in maternal plasma reflects fetal growth and it may be a useful indicator of placental function.

Noninvasive reconstruction of placental methylome from maternal plasma DNA: Potential for prenatal testing and monitoring

OBJECTIVE

During human pregnancy, the DNA methylation of placental tissue is highly relevant to the normal growth and development of the fetus; therefore, methylomic analysis of the placental tissue possesses high research and clinical value in prenatal testing and monitoring. Thus, our aim is to develop an approach for reconstruction of the placental methylome, which should be completely noninvasive and achieve high accuracy and resolution.

RESULTS

We propose a novel size-based algorithm, FEtal MEthylome Reconstructor (FEMER), to noninvasively reconstruct the placental methylome by genomewide bisulfite sequencing and size-based analysis of maternal plasma DNA. By applying FEMER on a real clinical dataset, we demonstrate that FEMER achieves both high accuracy and resolution, thus provides a high-quality view of the placental methylome from maternal plasma DNA. FEtal MEthylome Reconstructor could also predict the DNA methylation profile of CpG islands with high accuracy, thus shows potential in monitoring of key genes involved in placental/fetal development. Source code and testing datasets for FEMER are available at http://sunlab.cpy.cuhk.edu.hk/FEMER/.

CONCLUSION

FEtal MEthylome Reconstructor could enhance the noninvasive fetal/placental methylomic analysis and facilitate its application in prenatal testing and monitoring.

The lncRNA MALAT1 is a novel biomarker for gastric cancer metastasis

The metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is frequently over-expressed and serves as a prognostic marker in human cancers. However, little is known about the role of MALAT1 in gastric cancer. Here, we reported that the tissue and plasma MALAT1 levels were significantly higher in gastric cancer patients with distant metastasis (P<0.01) than patients without distant metastasis and the healthy controls. In addition, high levels of plasma MALAT1 independently correlated to a poor prognosis for gastric cancer patients (hazard ratio, 0.242; 95% CI, 0.154-0.836; P=0.036; Cox regression analysis). Functional studies revealed that knockdown of MALAT1 could inhibit cell proliferation, cell cycle progression, migration and invasion, and promote apoptosis in gastric cancer cells. Furthermore, the miR-122-IGF-1R signaling correlated with the dysregulated MALAT1 expression in gastric cancer. These data suggest that MALAT1 could function as an oncogene in gastric cancer, and high MALAT1 level could serve as a potential biomarker for the distant metastasis of gastric cancer.

Epigenetic approaches for the detection of fetal DNA in maternal plasma

The presence of fetal DNA in the plasma of pregnant women has opened up new possibilities for noninvasive prenatal diagnosis. Over the past decades, different types of fetal markers have been developed, initially based on discriminative genetic markers such as male-specific signals or paternally-inherited polymorphisms, and gradually evolved to the detection of fetal-specific transcripts or epigenetic signatures. This development has extended the coverage of the application of cell-free fetal DNA to essentially all pregnancies, regardless of the gender of the fetus or its polymorphic status. In this review, we present an overview of the development of noninvasive prenatal diagnosis through epigenetics. We introduce the basis of how fetal DNA could be detected from a large background of maternal DNA in maternal plasma based on fetal-specific DNA methylation patterns. We evaluate the methodologies involved and discuss the factors that affect the robustness of the detection. We review the progress in adopting fetal epigenetic markers for noninvasive prenatal assessment of fetal chromosomal aneuploidies and pregnancy-associated disorders. We conclude with comments on the future directions regarding the search for new fetal epigenetic markers and the clinical implementation of epigenetic approaches for noninvasive prenatal diagnosis.

Integrative single-cell and cell-free plasma RNA transcriptomics elucidates placental cellular dynamics

The human placenta is a dynamic and heterogeneous organ critical in the establishment of the fetomaternal interface and the maintenance of gestational well-being. It is also the major source of cell-free fetal nucleic acids in the maternal circulation. Placental dysfunction contributes to significant complications, such as preeclampsia, a potentially lethal hypertensive disorder during pregnancy. Previous studies have identified significant changes in the expression profiles of preeclamptic placentas using whole-tissue analysis. Moreover, studies have shown increased levels of targeted RNA transcripts, overall and placental contributions in maternal cell-free nucleic acids during pregnancy progression and gestational complications, but it remains infeasible to noninvasively delineate placental cellular dynamics and dysfunction at the cellular level using maternal cell-free nucleic acid analysis. In this study, we addressed this issue by first dissecting the cellular heterogeneity of the human placenta and defined individual cell-type-specific gene signatures by analyzing more than 24,000 nonmarker selected cells from full-term and early preeclamptic placentas using large-scale microfluidic single-cell transcriptomic technology. Our dataset identified diverse cellular subtypes in the human placenta and enabled reconstruction of the trophoblast differentiation trajectory. Through integrative analysis with maternal plasma cell-free RNA, we resolved the longitudinal cellular dynamics of hematopoietic and placental cells in pregnancy progression. Furthermore, we were able to noninvasively uncover the cellular dysfunction of extravillous trophoblasts in early preeclamptic placentas. Our work showed the potential of integrating transcriptomic information derived from single cells into the interpretation of cell-free plasma RNA, enabling the noninvasive elucidation of cellular dynamics in complex pathological conditions.

Cell-free Fetal Nucleic Acid Identifier Markers in Maternal Circulation

From the discovery of cell-free fetal (cff)-DNA in 1997 so far, many studies have been performed on various aspects of cff-nucleic acid. It is undoubted that currently, invasive prenatal diagnosis progresses to the noninvasive test. However, there are many problems. One of the most challenging issues in this field is differentiation and detection of the small amount of cff-nucleic acid in maternal plasma. Many markers and methods have been used for this purpose. This review makes an attempt to review and compare the studies in the field. Six identifier markers including Y-specific sequence, polymorphisms, epigenetic difference, DNA size difference, fetal mRNA, and microRNA as well as the advantages and disadvantages of each marker are discussed. This review provides a relatively perfect set on cff-nucleic acid biomarkers in various physiological and pathological status of pregnancy, helping to review and compare the prior obtained results, and improving designation in future studies.

First trimester screening of circulating C19MC microRNAs and the evaluation of their potential to predict the onset of preeclampsia and IUGR

Objectives

A nested case control study of a longitudinal cohort comparing pregnant women enrolled at 10 to 13 gestational weeks was carried out to evaluate risk assessment for preeclampsia and IUGR based on circulating placental specific C19MC microRNAs in early pregnancy.

Methods

The expression of placental specific C19MC microRNAs (miR-516b-5p, miR-517-5p, miR-518b, miR-520a-5p, miR-520h, and miR-525-5p) was determined in plasma samples from pregnancies that subsequently developed preeclampsia (n = 21), IUGR (n = 18), and 58 normal pregnancies using real-time PCR and comparative Ct method relative to synthetic Caenorhabditis elegans microRNA (cel-miR-39).

Results

Circulating C19MC microRNAs were up-regulated (miR-517-5p, p = 0.005; miR-518b, p = 0.013; miR-520h, p = 0.021) or showed a trend toward up-regulation in patients destined to develop preeclampsia (miR-520a-5p, p = 0.067; miR-525-5p, p = 0.073). MiR-517-5p had the best predictive performance for preeclampsia with a sensitivity of 42.9%, a specificity of 86.2%, a PPV of 52.9% and a NPV of 80.6%. The combination of all examined circulating C19MC microRNAs had no advantage over using only the miR-517-5p biomarker to predict the occurrence of preeclampsia (a sensitivity of 20.6%, a specificity of 90.8%, a PPV of 44.8%, and a NPV of 76.0%).

Conclusions

Up-regulation of miR-517-5p, miR-518b and miR-520h was associated with a risk of later development of preeclampsia. First trimester screening of extracellular miR-517-5p identified a proportion of women with subsequent preeclampsia. No circulating C19MC microRNA biomarkers were identified that could predict later occurrence of IUGR.

A Forward Look At Noninvasive Prenatal Testing

Genomic abnormalities are a leading cause of birth defects and pregnancy complications, including in utero growth retardation and risk of miscarriage. Traditional invasive methods detecting such genomic abnormalities pose a relative risk to mother and unborn fetus. Non-invasive prenatal testing (NIPT) is a method that determines the genomic status of a fetus in utero by analyzing circulating fetal DNA in maternal plasma or serum. This review comes at a time when more and more physicians and hospitals might be using NIPT; there is great potential in extending this technology to other diagnostic applications. We discuss here the most current advances in diagnostic NIPT, its applications and limitations, as well as the development of future technology and possible clinical applications.

Does Formaldehyde Increase Cell Free DNA in Maternal Plasma Specimens?

BACKGROUND

There have been conflicting observations reported in the literature regarding the effects of formaldehyde in the recovery of cell free fetal DNA (CFF DNA) from maternal plasma. The aim of the present study was to assess the effect of formaldehyde treatment on circulating cell free DNA.

METHODS

We conducted this study using blood specimens collected from 11 pregnant women, each of whom was carrying a male fetus. DYS14 and HBB real time assays were performed to quantify fetal and total circulating cell free DNA from formaldehyde treated and untreated maternal plasma specimens, respectively.

RESULTS

The concentration of total circulating cell free DNA in formaldehyde-treated maternal plasma was reduced, compared with untreated maternal plasma (n = 11; P = .02). The percentage of CFF DNA between formaldehyde-treated and untreated maternal plasma specimens did not differ significantly (n = 11; P = .15).

CONCLUSION

Addition of formaldehyde does not significantly enhance the proportion of cell free fetal DNA when blood specimens are processed without delay.