Circulating exosomal and Argonaute-bound microRNAs in preeclampsia

MicroRNA analysis of medium/large placenta extracellular vesicles in normal and preeclampsia pregnancies

Background

Preeclampsia (PE) is a hypertensive disorder of pregnancy, affecting 2%-8% of pregnancies worldwide, and is the leading cause of adverse maternal and fetal outcomes. The disease is characterized by oxidative and cellular stress and widespread endothelial dysfunction. While the precise mechanisms are not entirely understood, the pathogenesis of PE is closely linked to placental dysfunction and, to some extent, syncytiotrophoblast extracellular vesicle release (STB-EVs). These vesicles can be divided into the less well-studied medium/large EVs (220-1,000 nm) released in response to stress and small EVs (<220 nm) released as a component of intercellular communication. The previously described production of m/lSTB-EVs in response to cellular stress combined with the overwhelming occurrence of cellular and oxidative stress in PE prompted us to evaluate the microRNAome of PE m/lSTB-EVs. We hypothesized that the microRNAome profile of m/lSTB-EVs is different in PE compared to normal pregnancy (NP), which might permit the identification of potential circulating biomarkers not previously described in PE.

Methods/study design

We performed small RNA sequencing on medium/large STB-EVs isolated from PE and NP placentae using dual-lobe ex vivo perfusion. The sequencing data was bioinformatically analyzed to identify differentially regulated microRNAs. Identified microRNAs were validated with quantitative PCR analysis. We completed our analysis by performing an in-silico prediction of STB-EV mechanistic pathways.

Results

We identified significant differences between PE and NP in the STB-EVs micro ribonucleic acid (microRNA) profiles. We verified the differential expression of hsa-miR-193b-5p, hsa-miR-324-5p, hsa-miR-652-3p, hsa-miR-3196, hsa-miR-9-5p, hsa-miR-421, and hsa-miR-210-3p in the medium/large STB-EVs. We also confirmed the differential abundance of hsa-miR-9-5p in maternal serum extracellular vesicles (S EVs). In addition, we integrated the results of these microRNAs into the previously published messenger RNA (mRNA) data to better understand the relationship between these biomolecules.

Conclusions

We identified a differentially regulated micro-RNA, hsa-miR-9-5p, that may have biomarker potential and uncovered mechanistic pathways that may be important in the pathophysiology of PE.

Advances in extracellular vesicles as mediators of cell-to-cell communication in pregnancy

Cell-to-cell communication mediated by Extracellular Vesicles (EVs) is a novel and emerging area of research, especially during pregnancy, in which placenta derived EVs can facilitate the feto-maternal communication. EVs comprise a heterogeneous group of vesicle sub-populations with diverse physical and biochemical characteristics and originate by specific biogenesis mechanisms. EVs transfer molecular cargo (including proteins, nucleic acids, and lipids) between cells and are critical mediators of cell communication. There is growing interest among researchers to explore into the molecular cargo of EVs and their functions in a physiological and pathological context. For example, inflammatory mediators such as cytokines are shown to be released in EVs and EVs derived from immune cells play key roles in mediating the immune response as well as immunoregulatory pathways. Pregnancy complications such as gestational diabetes mellitus, preeclampsia, intrauterine growth restriction and preterm birth are associated with altered levels of circulating EVs, with differential EV cargo and bioactivity in target cells. This implicates the intriguing roles of EVs in reprogramming the maternal physiology during pregnancy. Moreover, the capacity of EVs to carry bioactive molecules makes them a promising tool for biomarker development and targeted therapies in pregnancy complications. This review summarizes the physiological and pathological roles played by EVs in pregnancy and pregnancy-related disorders and describes the potential of EVs to be translated into clinical applications in the diagnosis and treatment of pregnancy complications.

Exosomal small RNA profiling in first-trimester maternal blood explores early molecular pathways of preterm preeclampsia

Introduction

Preeclampsia (PE) is a severe obstetrical syndrome characterized by new-onset hypertension and proteinuria and it is often associated with fetal intrauterine growth restriction (IUGR). PE leads to long-term health complications, so early diagnosis would be crucial for timely prevention. There are multiple etiologies and subtypes of PE, and this heterogeneity has hindered accurate identification in the presymptomatic phase. Recent investigations have pointed to the potential role of small regulatory RNAs in PE, and these species, which travel in extracellular vesicles (EVs) in the circulation, have raised the possibility of non-invasive diagnostics. The aim of this study was to investigate the behavior of exosomal regulatory small RNAs in the most severe subtype of PE with IUGR.

Methods

We isolated exosomal EVs from first-trimester peripheral blood plasma samples of women who later developed preterm PE with IUGR (n=6) and gestational age-matched healthy controls (n=14). The small RNA content of EVs and their differential expression were determined by next-generation sequencing and further validated by quantitative real-time PCR. We also applied the rigorous exceRpt bioinformatics pipeline for small RNA identification, followed by target verification and Gene Ontology analysis.

Results

Overall, >2700 small RNAs were identified in all samples and, of interest, the majority belonged to the RNA interference (RNAi) pathways. Among the RNAi species, 16 differentially expressed microRNAs were up-regulated in PE, whereas up-regulated and down-regulated members were equally found among the six identified Piwi-associated RNAs. Gene ontology analysis of the predicted small RNA targets showed enrichment of genes in pathways related to immune processes involved in decidualization, placentation and embryonic development, indicating that dysregulation of the induced small RNAs is connected to the impairment of immune pathways in preeclampsia development. Finally, the subsequent validation experiments revealed that the hsa_piR_016658 piRNA is a promising biomarker candidate for preterm PE associated with IUGR.

Discussion

Our rigorously designed study in a homogeneous group of patients unraveled small RNAs in circulating maternal exosomes that act on physiological pathways dysregulated in preterm PE with IUGR. Therefore, our small RNA hits are not only suitable biomarker candidates, but the revealed biological pathways may further inform us about the complex pathology of this severe PE subtype.

Circulating miRNAs and Preeclampsia: From Implantation to Epigenetics

In this review, we comprehensively present the literature on circulating microRNAs (miRNAs) associated with preeclampsia, a pregnancy-specific disease considered the primary reason for maternal and fetal mortality and morbidity. miRNAs are single-stranded non-coding RNAs, 20-24 nt long, which control mRNA expression. Changes in miRNA expression can induce a variation in the relative mRNA level and influence cellular homeostasis, and the strong presence of miRNAs in all body fluids has made them useful biomarkers of several diseases. Preeclampsia is a multifactorial disease, but the etiopathogenesis remains unclear. The functions of trophoblasts, including differentiation, proliferation, migration, invasion and apoptosis, are essential for a successful pregnancy. During the early stages of placental development, trophoblasts are strictly regulated by several molecular pathways; however, an imbalance in these molecular pathways can lead to severe placental lesions and pregnancy complications. We then discuss the role of miRNAs in trophoblast invasion and in the pathogenesis, diagnosis and prediction of preeclampsia. We also discuss the potential role of miRNAs from an epigenetic perspective with possible future therapeutic implications.

Small RNA sequencing of exosomal microRNAs reveals differential expression of microRNAs in preeclampsia

Preeclampsia (PE) is one of the most common hypertensive disorders of pregnancy. It is a dangerous condition with a high mortality rate in mothers and fetuses and is associated with a lack of early diagnosis and effective treatment. While the etiology of the disease is complex and obscure, it is now clear that the placenta is central to disease progression. Exosomal microRNAs (miRNAs) are possible mediators that regulate placenta-related physiological and pathological processes. Placental mesenchymal stem cells have considerable potential to help us understand the pathogenesis and treatment of pregnancy-related diseases. Here, we investigate the exosomal miRNA profiles of human placenta-derived mesenchymal stem cells between healthy pregnant women and those with PE. We performed small RNA sequencing to obtain miRNA profiles, and conducted enrichment analysis of the miRNA target genes to identify differentially expressed miRNAs associated with PE. Overall, we detected 1795 miRNAs; among them, 206 were differentially expressed in women with PE, including 35 upregulated and 171 downregulated miRNAs, when compared with healthy pregnant women. Moreover, we identified possible functions and pathways associated with PE, including angiogenesis, cell proliferation, migration and invasion, and the coagulation-fibrinolysis balance. Eventually, we proposed hsa-miR-675-5p, hsa-miR-3614-5p, and hsa-miR-615-5p as potential regulators of the pathogenesis of PE, and constructed a miRNA-target gene network. Our study identifies possible candidate biomarkers for the diagnosis of PE, and introduces a new direction for further understanding the pathogenesis of PE.

Extracellular vesicles during the three trimesters of pregnancy

OBJECTIVES

Extracellular vesicles (EVs) are cell-derived particles released during different pathophysiological processes and emerging as relevant players in inter-cellular crosstalk. Previous studies have highlighted the role of EVs as potential biomarkers for several pregnancy complications, including miscarriage, pre-eclampsia and gestational diabetes. Despite that, the actual distribution of EVs through gestation has not been reported yet. The aim of this study was to report the concentration of different sub-types of EVs in the first, second and third trimester of pregnancy and to correlate them with different pregnancy and ultrasound characteristics.

STUDY DESIGNS

Prospective observational study including uncomplicated pregnancies in the first, second and third trimester of pregnancy. The first aim of the study was to report the concentration of the EVs derived from endothelial, epithelial, platelet and leukocyte cells of maternal peripheral blood samples in the first, second and third trimester pregnancy using polychromatic flow cytometry. The secondary aim was to correlate EVs with neonatal birthweight and fetal Dopplers, including uterine and umbilical arteries. Un and multivariate analyses were used to compute the data.

RESULTS

64 women (20 in the first, 22 in the second and 22 in the third trimester of pregnancies) were included in the analysis. There was no difference in the median concentration of either platelet, leukocyte and endothelial EVs between the first, second and third trimester of pregnancy. The concentration of epithelial derived EVs was higher in the third compared to first and second trimester of pregnancy. When analyzing the percentage of EV vesicles through gestation, there was no difference in the percentage of either leukocyte or endothelial EVs through gestation. Conversely, the median percentage of platelet derived vesicles was higher in the first (48.7 %, IQR 34.1-58.5) compared to second (34.0 %, IQR 22.7-44.9) and third (9.13 %, IQR 5.01-12.1) trimester of pregnancy, while the median percentage of third trimester (6.01, IQR 2.42-7.34) epithelial derived vesicles was higher than that of the second (1.53 %, IQR 0.65-2.98), but not of the first (4.45 %, IQR 1.44-6.07) trimester. Finally, we found no association between the median concentration or percentage of endothelial, epithelial, leukocyte vesicles, neonatal birthweight and fetal or maternal Dopplers.

CONCLUSIONS

Distribution of EVs examined does not change during the three trimesters of pregnancy and is not influenced by neonatal birthweight or maternal and fetal Dopplers. The findings from this study allows a more objective interpretation of studies comparing EVs in pregnancies with compared to those without obstetric complication. EVs in future can be used for "liquid biopsy" for the early diagnosis of pathological pregnancies up to the development of possible screening protocols.

The role of extracellular vesicles in intercellular communication in human reproduction

Embryo-maternal cross-talk has emerged as a vitally important process for embryo development and implantation, which is driven by secreted factors and extracellular vesicles (EVs). The EV cargo of bioactive molecules significantly influences target cells and primes them for critical stages of reproductive biology, including embryo development, adhesion, and implantation. Recent research has suggested that EVs and their cargo represent a powerful non-invasive tool that can be leveraged to assess embryo and maternal tissue quality during assisted reproduction treatments. Here, we review the current scientific literature regarding the intercellular cross-talk between embryos and maternal tissues from fertilization to implantation, focusing on human biology and signaling mechanisms identified in animal models.

Potassium Channels in the Uterine Vasculature: Role in Healthy and Complicated Pregnancies

A progressive increase in maternal uterine and placental blood flow must occur during pregnancy to sustain the development of the fetus. Changes in maternal vasculature enable an increased uterine blood flow, placental nutrient and oxygen exchange, and subsequent fetal development. K⁺ channels are important modulators of vascular function, promoting vasodilation, inducing cell proliferation, and regulating cell signaling. Different types of K⁺ channels, such as Ca²⁺-activated, ATP-sensitive, and voltage-gated, have been implicated in the adaptation of maternal vasculature during pregnancy. Conversely, K⁺ channel dysfunction has been associated with vascular-related complications of pregnancy, including intrauterine growth restriction and pre-eclampsia. In this article, we provide an updated and comprehensive literature review that highlights the relevance of K⁺ channels as regulators of uterine vascular reactivity and their potential as therapeutic targets.

Serum HIF-1α Levels, miR-210 Expressions, and Reactive Oxygen Species Levels in Early Abortion and Normal Pregnancy

Background: The blastocyst implants in a relatively hypoxic state. Hypoxic state triggers hypoxia-inducible factor-1α (HIF-1ɑ) production, upregulates the transcription factor miR-210, and stimulates reactive oxygen species (ROS) production by trophoblast cells. HIF-1α also increases the expression of miR-210. High expression of micro-RNA 210 (miR-210) suppresses mitochondrial respiration, increasing ROS production. High level of ROS may result in DNA damage or cell disfunction, thereby impaired trophoblast invasion, leading to early abortion. This study aims to determine the differences of serum HIF-1ɑ levels, miR-210 expressions, and ROS levels between early abortion and normal pregnancy. Method: This cross-sectional comparative study was conducted in Dr. M. Djamil Hospital Padang, Andalas University Hospital, and 5 Public Health Centers in Padang. Fifty-patients with gestational age less than 12 weeks (25 early abortions and 25 normal pregnancies) were included in this study. All samples were tested for HIF-1ɑ and ROS level using enzyme-linked immunosorbent assay (ELISA) method, and miR-210 expression using real-time polymerase chain reaction (PCR) technique. Spearman correlation and  Mann Whitney test. was used in this study. Results: Both study groups were equivalent in terms of age, gestational age, and gravidity (p = 0.51, 0.453 and 1.00). The median of HIF-1ɑ level, miR-210 expression, and ROS level were higher in early abortions than normal pregnancies i.e (3.73 vs 3.42) ng/mL (p = 0.016), (43.55 vs 17.85) copies/ng (p = 0.027), and (1.36 vs 1.20) ng/mL (p = 0.003). The coefficient correlations were 0.16 between HIF-1ɑ level and miR-210 expression (p=0.267), 0.46 between HIF-1ɑ level and ROS level (p=0.001), and 0.18 between miR-210 expression and ROS level (p=0.207). Conclusion: HIF-1ɑ level, miR-210 expression, and ROS level were associated with early abortion. HIF-1ɑ level has a correlation with ROS level.

Involvement of extracellular vesicle-encapsulated miRNAs in human reproductive disorders: a systematic review

In recent years, extracellular vesicles (EVs) have emerged as essential players in cell-to-cell communication, particularly having an active regulating role in biological systems. Because reproductive-associated processes are not exempt of this communication, multiple studies have been devoted to this realm, focusing on gamete maturation, embryo implantation or fetal development. The aim of the present review was to comprehensively and systematically collect evidence about the function of the microRNA (miRNA) encapsulated in EVs isolated from different reproductive tissues or fluids in reproductive-related diseases. Following PRISMA guidelines, we conducted a systematic search of the literature published in MEDLINE-PubMed until the end of February 2021. After selection, 32 studies were included in the qualitative review comparing the miRNA expression profile in EVs between different pathological disorders. Most reports showed the potential of the miRNAs carried by EVs to be used as putative biomarkers of reproductive disorders, including pregnancy affections, disease progression and quality of preimplantation embryos. The most relevant miRNAs were found to be highly heterogeneous among studies, with some conflicting results. Further research is thus warranted to address whether cofounding factors, such as the methods to isolate EVs and miRNAs, the subset of EVs, the criteria of patient selection, the timing of sample retrieval, or any other factor, may explain the inconsistencies between studies.

Quantitative proteomic analysis of serum-purified exosomes identifies putative pre-eclampsia-associated biomarkers

BACKGROUND

The high incidence of pre-eclampsia, which affects 2-7% of all pregnancies, remains a major health concern. Detection of pre-eclampsia before the appearance of clinical symptoms is essential to allow early intervention, and would benefit from identification of plasma/serum biomarkers to help guide diagnosis and treatment. Liquid biopsy has emerged as a promising source of protein biomarkers that circumvents some of the inherent challenges of proteome-wide analysis of plasma/serum. In this respect, purified exosomes have the added benefit of being carriers of intercellular communication both in physiological and pathological conditions.

METHODS

We compared the protein complement of purified exosomes from three different collections of control and pre-eclamptic serum samples, obtained at the end of the second trimester of pregnancy and at delivery. We employed shotgun label-free proteomics to investigate differential protein expression, which was then validated by targeted proteomics.

RESULTS

We developed a purification method that yielded highly enriched exosome preparations. The presence of specific pregnancy protein markers suggested that a significant proportion of purified exosomes derived from tissues related to pregnancy. Quantitative proteomic analyses allowed us to identify 10, 114 and 98 differentially-regulated proteins in the three sample collections, with a high degree of concordance. Functional analysis suggested that these proteins participate in biological processes related to pre-eclampsia, including angiogenesis, inflammation and cell migration. The differential abundance of 66 proteins was validated by targeted proteomics. Finally, we studied the impact of the pre-eclampsia-associated exosomes in the proteome using an in vitro cellular model.

CONCLUSIONS

We have identified and validated differential exosomal proteins in liquid biopsy of pregnant women that open new possibilities for early detection of pre-eclampsia. Additionally, the functional impact of the proteome composition of purified pre-eclamptic exosomes in target cells provides new information to better understand changes in embryo-maternal interactions and, consequently, the pathogenesis of this disease.

Preeclamptic Women Have Disrupted Placental microRNA Expression at the Time of Preeclampsia Diagnosis: Meta-Analysis

Introduction: Preeclampsia (PE) is a pregnancy-associated, multi-organ, life-threatening disease that appears after the 20th week of gestation. The aim of this study was to perform a systematic review and meta-analysis to determine whether women with PE have disrupted miRNA expression compared to women who do not have PE. Methods: We conducted a systematic review and meta-analysis of studies that reported miRNAs expression levels in placenta or peripheral blood of pregnant women with vs. without PE. Studies published before October 29, 2021 were identified through PubMed, EMBASE and Web of Science. Two reviewers used predefined forms and protocols to evaluate independently the eligibility of studies based on titles and abstracts and to perform full-text screening, data abstraction and quality assessment. Standardized mean difference (SMD) was used as a measure of effect size. Results: 229 publications were included in the systematic review and 53 in the meta-analysis. The expression levels in placenta were significantly higher in women with PE compared to women without PE for miRNA-16 (SMD = 1.51,95%CI = 0.55-2.46), miRNA-20b (SMD = 0.89, 95%CI = 0.33-1.45), miRNA-23a (SMD = 2.02, 95%CI = 1.25-2.78), miRNA-29b (SMD = 1.37, 95%CI = 0.36-2.37), miRNA-155 (SMD = 2.99, 95%CI = 0.83-5.14) and miRNA-210 (SMD = 1.63, 95%CI = 0.69-2.58), and significantly lower for miRNA-376c (SMD = -4.86, 95%CI = -9.51 to -0.20). An increased level of miRNK-155 expression was found in peripheral blood of women with PE (SMD = 2.06, 95%CI = 0.35-3.76), while the expression level of miRNA-16 was significantly lower in peripheral blood of PE women (SMD = -0.47, 95%CI = -0.91 to -0.03). The functional roles of the presented miRNAs include control of trophoblast proliferation, migration, invasion, apoptosis, differentiation, cellular metabolism and angiogenesis. Conclusion: miRNAs play an important role in the pathophysiology of PE. The identification of differentially expressed miRNAs in maternal blood creates an opportunity to define an easily accessible biomarker of PE.

Differential and targeted vesiculation: pathologic cellular responses to elevated arterial pressure

Extracellular vesicles are small membrane-enclosed particles released during cell activation or injury. They have been investigated for several decades and found to be secreted in various diseases. Their pathogenic role is further supported by the presence of several important molecules among their cargo, including proteins, lipids, and nucleic acids. Many studies have reported enhanced and targeted extracellular vesicle biogenesis in diseases that involve chronic or transient elevation of arterial pressure resulting in endothelial dysfunction, within either the general circulatory system or specific local vascular beds. In addition, several associated pathologic processes have been studied and reported. However, the role of elevated pressure as a common pathogenic trigger across vascular domains and disease chronicity has not been previously described. This review will therefore summarize our current knowledge of the differential and targeted biogenesis of extracellular vesicles in major diseases that are characterized by elevated arterial pressure leading to endothelial dysfunction and propose a unified theory of pressure-induced extracellular vesicle-mediated pathogenesis.

Placental mediated mechanisms of perinatal brain injury: Evolving inflammation and exosomes

Pregnancy is an inflammatory process that is carefully regulated by the placenta via immunomodulation and cell-to-cell communication of maternal and fetal tissues. Exosomes, types of extracellular vesicles, facilitate the intercellular communication and traffic biologically modifying cargo within the maternal-placental-fetal axis in normal and pathologic pregnancies. Chorioamnionitis is characterized by inflammation of chorioamniotic membranes that produces systemic maternal and fetal inflammatory responses of cytokine dysregulation and has been associated with brain injury and neurodevelopmental disorders. This review focuses on how pathologic placental exosomes propagate acute and chronic inflammation leading to brain injury. The evidence reviewed here highlights the need to investigate exosomes from pathologic pregnancies and those with known brain injury to identify new diagnostics, biomarkers, and potential therapeutic targets.

Maternal Circulating Exosomal miRNAs as Non-invasive Biomarkers for the Prediction of Fetal Ventricular Septal Defect

Objective: This study aimed to identify maternal circulating exosomal miRNAs as potential non-invasive biomarkers for the early detection of fetal ventricular septal defects (VSDs).

Methods: In total, 182 pregnant women, comprising 91 VSD cases and 91 matched controls, were included in this study. Exosomes were isolated; dysregulated exosomal miRNAs were profiled using next-generation sequencing. Differential abundance of miRNAs was verified using quantitative real-time polymerase chain reaction (qRT-PCR). Diagnostic accuracy was evaluated by constructing receiver operating characteristic (ROC) curves.

Results: In total, 77 serum exosomal miRNAs were found to be differentially expressed in the VSD group compared to their expression in the control group. Among these, five downregulated exosomal miRNAs were validated using qRT-PCR. hsa-miR-146a-5p was identified to be capable of distinguishing VSD cases from controls (area under the ROC curve [AUC]: 0.997; p < 1.00E-05).

Conclusion: Circulating exosomal miRNAs, particularly hsa-miR-146a-5p, may be predictive biomarkers for the non-invasive prenatal diagnosis of fetal VSDs.

Association of Exosomal miR-210 with Signaling Pathways Implicated in Lung Cancer

MicroRNA is a class of non-coding RNA involved in post-transcriptional gene regulation. Aberrant expression of miRNAs is well-documented in molecular cancer biology. Extensive research has shown that miR-210 is implicated in the progression of multiple cancers including that of the lung, bladder, colon, and renal cell carcinoma. In recent years, exosomes have been evidenced to facilitate cell–cell communication and signaling through packaging and transporting active biomolecules such as miRNAs and thereby modify the cellular microenvironment favorable for lung cancers. MiRNAs encapsulated inside the lipid bilayer of exosomes are stabilized and transmitted to target cells to exert alterations in the epigenetic landscape. The currently available literature indicates that exosomal miR-210 is involved in the regulation of various lung cancer-related signaling molecules and pathways, including STAT3, TIMP-1, KRAS/BACH2/GATA-3/RIP3, and PI3K/AKT. Here, we highlight major findings and progress on the roles of exosomal miR-210 in lung cancer.

Role of Extracellular Vesicles in Placental Inflammation and Local Immune Balance

Background

Pregnancy maintenance depends on the formation of normal placentas accompanied by trophoblast invasion and vascular remodeling. Various types of cells, such as trophoblasts, endothelial cells, immune cells, mesenchymal stem cells (MSCs), and adipocytes, mediate cell-to-cell interactions through soluble factors to maintain normal placental development. Extracellular vesicles (EVs) are diverse nanosized to microsized membrane-bound particles released from various cells. EVs contain tens to thousands of different RNA, proteins, small molecules, DNA fragments, and bioactive lipids. EV-derived microRNAs (miRNAs) and proteins regulate inflammation and trophoblast invasion in the placental microenvironment. Maternal-fetal communication through EV can regulate the key signaling pathways involved in pregnancy maintenance, from implantation to immune regulation. Therefore, EVs and the encapsulating factors play important roles in pregnancy, some of which might be potential biomarkers.

Conclusion

In this review, we have summarized published studies about the EVs in the placentation and pregnancy-related diseases. By summarizing the role of EVs and their delivering active molecules in pregnancy-related diseases, it provides novel insight into the diagnosis and treatment of diseases.

The Potential Role of Serum Exosomes in Preeclampsia

Preeclampsia is a serious pregnancy-specific disease that affects about 5%-8% of pregnant women and is the main reason for the increase in maternal and perinatal mortality. Due to unknown etiology, preeclampsia is still the main cause of increased mortality in maternal and perinatal infants, which is mainly manifested by new hypertension after 20 weeks of pregnancy. As the pathogenesis has not been fully elucidated, early diagnosis and full treatment are lacking. Exosomes secreted from the placenta to the peripheral circulation may be involved in the pathogenesis of preeclampsia and can be detected from the plasma of pregnant women after 6 weeks of pregnancy. Related studies have shown that the levels of exosomes in preeclampsia have changed, and the protein and miRNA expression profiles are also different. Therefore, monitoring changes in plasma exosomes and expression profiles may provide new ideas and new perspectives for the prediction, diagnosis and treatment of preeclampsia.

An Insight on the Role of Altered Function and Expression of Exosomes and MicroRNAs in Female Reproductive Diseases

Exosomes are small bilayer-lipid membrane vesicles secreted by living cells that are able to transfer regulatory molecules and genetic information from one cell to another. These vesicles are enriched with several nucleic acids including mRNAs, microRNAs (miRNAs), other non-coding RNAs, as well as proteins and lipids. Alterations in the exosomal content and functions are observed in numerous reproductive diseases in both animals and human cases. MicroRNAs, a class of small endogenous RNA molecules, can negatively regulate gene expression at the post-transcription level. Aberrant microRNA expression has been reported in multiple human reproductive diseases such as polycystic ovary syndrome, preeclampsia, uterine leiomyomata, ovarian cancer, endometriosis, and Asherman's syndrome. This study focuses to review recent research on alterations of microRNA expression and the role of exosomes in female reproductive diseases. It has been demonstrated that exosomes may be a potential therapeutic approach in various female reproductive diseases. In addition, changes in expression of microRNAs act as molecular biomarkers for diagnosis of several reproductive diseases in women, and regulation of their expression can potentially reduce infertility.

Placenta-Derived MicroRNAs in the Pathophysiology of Human Pregnancy

In placental mammals, reproductive success, and maternal-fetal health substantially depend on a well-being placenta, the interface between the fetus and the mother. Disorders in placental cells are tightly associated with adverse pregnancy outcomes including preeclampsia (PE), fetal growth restriction, etc. MicroRNAs (miRNAs) represent small non-coding RNAs that regulate post-transcriptional gene expression and are integral to a wide range of healthy or diseased cellular proceedings. Numerous miRNAs have been detected in human placenta and increasing evidence is revealing their important roles in regulating placental cell behaviors. Recent studies indicate that placenta-derived miRNAs can be released to the maternal circulation via encapsulating into the exosomes, and they potentially target various maternal cells to provide a hormone-like means of intercellular communication between the mother and the fetus. These placental exosome miRNAs are attracting more and more attention due to their differential expression in pregnant complications, which may provide novel biomarkers for prediction of the diseases. In this review, we briefly summarize the current knowledge and the perspectives of the placenta-derived miRNAs, especially the exosomal transfer of placental miRNAs and their pathophysiological relevance to PE. The possible exosomal-miRNA-targeted strategies for diagnosis, prognosis or therapy of PE are highlighted.

Downregulating miR-96-5p promotes proliferation, migration, and invasion, and inhibits apoptosis in human trophoblast cells via targeting DDAH1

Several microRNAs (miRs) have been found to have modulating effects on trophoblast functions, yet the biological role and function of miR-96-5p and its interaction with Dimethylarginine Dimethylaminohydrolase 1 (DDAH1) remained poorly understood. After lentivirus transfection, the proliferation, migration, invasion and apoptosis of human trophoblast cells HTR-8/SVneo and SGHPL-4 were determined by Cell Counting Kit-8 (CCK-8) assay, scratch assay, Transwell, and flow cytometry, respectively. Relative expressions of miR-96-5p, DDAH1, and apoptosis-related proteins (B-cell lymphoma 2, Bcl-2; Bcl-2-associated X protein, Bax; cleaved (C) caspase-3) were detected via quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot as needed. The target gene of miR-96-5p and their potential binding sites were predicted using TargetScan V7.2 and confirmed by dual-luciferase reporter assay. MiR-96-5p downregulation promoted proliferation, migration and invasion, suppressed apoptosis, and decreased miR-96-5p expression in trophoblast cells in vitro, while miR-96-5p upregulation had the opposite effects. DDAH1 was recognized as a target gene of miR-96-5p, and silencing DDAH1 reversed the effects of miR-96-5p downregulation on the proliferation, migration, invasion and apoptosis of trophoblast cells as well as the expressions of apoptosis-related proteins. MiR-96-5p downregulation promotes proliferation, migration, and invasion, and suppresses apoptosis in human trophoblast cells in vitro via targeting DDAH1, which provides evidence for the implication of miR-96-5p in the functional modulation of trophoblasts.

MicroRNA-210 Mediates Hypoxia-Induced Repression of Spontaneous Transient Outward Currents in Sheep Uterine Arteries During Gestation

[Figure: see text].

MicroRNA-mRNA Networks in Pregnancy Complications: A Comprehensive Downstream Analysis of Potential Biomarkers

Pregnancy complications are a major cause of fetal and maternal morbidity and mortality in humans. The majority of pregnancy complications initiate due to abnormal placental development and function. During the last decade, the role of microRNAs (miRNAs) in regulating placental and fetal development has become evident. Dysregulation of miRNAs in the placenta not only affects placental development and function, but these miRNAs can also be exported to both maternal and fetal compartments and affect maternal physiology and fetal growth and development. Due to their differential expression in the placenta and maternal circulation during pregnancy complications, miRNAs can be used as diagnostic biomarkers. However, the differential expression of a miRNA in the placenta may not always be reflected in maternal circulation, which makes it difficult to find a reliable biomarker for placental dysfunction. In this review, we provide an overview of differentially expressed miRNAs in the placenta and/or maternal circulation during preeclampsia (PE) and intrauterine growth restriction (IUGR), which can potentially serve as biomarkers for prediction or diagnosis of pregnancy complications. Using different bioinformatics tools, we also identified potential target genes of miRNAs associated with PE and IUGR, and the role of miRNA-mRNA networks in the regulation of important signaling pathways and biological processes.

Human Placenta Exosomes: Biogenesis, Isolation, Composition, and Prospects for Use in Diagnostics

Exosomes are 40–100 nm nanovesicles participating in intercellular communication and transferring various bioactive proteins, mRNAs, miRNAs, and lipids. During pregnancy, the placenta releases exosomes into the maternal circulation. Placental exosomes are detected in the maternal blood even in the first trimester of pregnancy and their numbers increase significantly by the end of pregnancy. Exosomes are necessary for the normal functioning of the placenta and fetal development. Effects of exosomes on target cells depend not only on their concentration but also on their intrinsic components. The biochemical composition of the placental exosomes may cause various complications of pregnancy. Some studies relate the changes in the composition of nanovesicles to placental dysfunction. Isolation of placental exosomes from the blood of pregnant women and the study of protein, lipid, and nucleic composition can lead to the development of methods for early diagnosis of pregnancy pathologies. This review describes the biogenesis of exosomes, methods of their isolation, analyzes their biochemical composition, and considers the prospects for using exosomes to diagnose pregnancy pathologies.

Extracellular Vesicles and Preeclampsia: Current Knowledge and Future Research Directions

Preeclampsia (PE) is associated with long-term morbidity in mothers and lifelong morbidities for their children, ranging from cerebral palsy and cognitive delay in preterm infants, to hypertension, diabetes and obesity in adolescents and young adults. There are several processes that are critical for development of materno-fetal exchange, including establishing adequate perfusion of the placenta by maternal blood, and the formation of the placental villous vascular tree. Recent studies provide persuasive evidence that placenta-derived extracellular vesicles (EVs) represent a significant intercellular communication pathway, and that they may play an important role in placental and endothelial cell (both fetal and maternal) function. These functions are known to be altered in PE. EVs can carry and transport a wide range of bioactive molescules that have potential to be used as biomarkers and therapeutic delivery tools for PE. EV content is often parent cell specific, thus providing an insight or "thumbprint" of the intracellular environment of the originating cell (e.g., human placenta). EV have been identified in plasma under both normal and pathological conditions, including PE. The concentration of EVs and their content in plasma has been reported to increase in association with disease severity and/or progression. Placenta-derived EVs have been identified in maternal plasma during normal pregnancy and PE pregnancies. They contain placenta-specific proteins and miRNAs and, as such, may be differentiated from maternally-derived EVs. The aim of this review, thus, is to describe the potential roles of EVs in preecmpatic pregnancies, focussing on EVs secreted from placental cells. The biogenesis, specificity of placental EVs, and methods used to characterise EVs in the context of PE pregnancies will be also discussed.

Exosomal microRNA-139-5p from mesenchymal stem cells accelerates trophoblast cell invasion and migration by motivation of the ERK/MMP-2 pathway via downregulation of protein tyrosine phosphatase

AIM

Exosomes present essential roles for intercellular interaction via extracellular pathways during systemic dysfunctions, including preeclampsia (PE). Here, we assessed the specific mechanism of mesenchymal stem cells (MSC)-originated exosomes in PE.

METHODS

The effects of exosomes on trophoblasts were studied by EdU, wound healing, Transwell and TUNEL assays. By microarray analysis, we found that exosomes enhanced the microRNA-139-5p (miR-139-5p) in trophoblasts, and confirmed the target gene of miR-139-5p by bioinformatics prediction and dual-luciferase reporter gene assay. At the same time, ERK/MMP-2 pathway-related biomolecules were assessed through Western blot analysis. The pathway inhibitor was used for rescue experiments. Finally, the effect of exosomes on the pathology of PE rats was verified by in vivo experiments.

RESULTS

The exosomes originated from hucMSC fostered the trophoblast cell migration, invasion and proliferation and obstructed apoptosis. Moreover, miR-139-5p could be transmitted to trophoblasts through hucMSC-secreted exosomes. miR-139-5p targeted protein tyrosine phosphatase (PTEN), which regulated the ERK/MMP-2 pathway. Inhibition of the ERK/MMP-2 pathway significantly reduced the promoting effect of exosomes on trophoblasts. Treatment with exosomes significantly lowered blood pressure values and reduced 24-h proteinuria in PE rats.

CONCLUSION

hucMSC-originated exosomes overexpressing miR-139-5p activated the ERK/MMP-2 pathway via PTEN downregulation, thus accelerating trophoblast cell invasion and migration, and blocking apoptosis. These results demonstrated that hucMSC-derived exosomes overexpressing miR-139-5p might be an innovative direction for therapeutic approaches against PE.

Extracellular vesicles: Mediators of embryo-maternal crosstalk during pregnancy and a new weapon to fight against infertility

In modern-day life, infertility is one of the major issues that can affect an individual, both physically and psychologically. Several anatomical, physiological, and genetic factors might contribute to the infertility of an individual. Intercellular communication between trophectoderm and endometrial epithelium triggers successful embryo implantation and thereby establishes pregnancy. Recent studies demonstrate that Extracellular vesicles (EVs) are emerging as one of the crucial components that are involved in embryo-maternal communication and promote pregnancy. Membrane-bound EVs release several secreted factors within the uterine fluid, which mediates an intermolecular transfer of EVs' cargos between blastocysts and endometrium. Emerging evidences indicate that several events like imbalance in the release of endometrial or placenta-derived EVs (exosomes/MVs), uptake of their content, failure of embryo selection might lead to implantation failure. Here in this review, we have discussed the current knowledge of the involvement of EVs in maternal-fetal communications during implantation and also highlighted the EVs' rejuvenating ability to overcome infertility-related issues. We also discussed the alteration of the EVs' cargo in different pathological conditions that lead to infertility. Therefore, this review would give a better understanding of EVs' contribution in successful embryo implantation, which could help in the development of new diagnostic tools and cell-free biologics to improve the in vivo reproductive process and to treat infertility by restoring normal reproductive functions.

Exploiting the placenta for nanoparticle-mediated drug delivery during pregnancy

A major challenge to treating diseases during pregnancy is that small molecule therapeutics are transported through the placenta and incur toxicities to the developing fetus. The placenta is responsible for providing nutrients, removing waste, and protecting the fetus from toxic substances. Thus, the placenta acts as a biological barrier between the mother and fetus that can be exploited for drug delivery. Nanoparticle technologies provide the opportunity for safe drug delivery during pregnancy by controlling how therapeutics interact with the placenta. In this Review, we present nanoparticle drug delivery technologies specifically designed to exploit the placenta as a biological barrier to treat maternal, placental, or fetal diseases exclusively, while minimizing off-target toxicities. Further, we discuss opportunities, challenges, and future directions for implementing drug delivery technologies during pregnancy.

Placental microRNAs: Responders to environmental chemicals and mediators of pathophysiology of the human placenta

MicroRNAs (miRNAs) are epigenetic modifiers that play an important role in the regulation of the expression of genes across the genome. miRNAs are expressed in the placenta as well as other organs, and are involved in several biological processes including the regulation of trophoblast differentiation, migration, invasion, proliferation, apoptosis, angiogenesis and cellular metabolism. Related to their role in disease process, miRNAs have been shown to be differentially expressed between normal placentas and placentas obtained from women with pregnancy/health complications such as preeclampsia, gestational diabetes mellitus, and obesity. This dysregulation indicates that miRNAs in the placenta likely play important roles in the pathogenesis of diseases during pregnancy. Furthermore, miRNAs in the placenta are susceptible to altered expression in relation to exposure to environmental toxicants. With relevance to the placenta, the dysregulation of miRNAs in both placenta and blood has been associated with maternal exposures to several toxicants. In this review, we provide a summary of miRNAs that have been assessed in the context of human pregnancy-related diseases and in relation to exposure to environmental toxicants in the placenta. Where data are available, miRNAs are discussed in their context as biomarkers of exposure and/or disease, with comparisons made across-tissue types, and conservation across studies detailed.

Placental extracellular vesicles and pre-eclampsia

Pre-eclampsia is a hypertensive disease of pregnancy characterized by new-onset hypertension, with either proteinuria and/or organ dysfunction. Pre-eclampsia is a leading cause of maternal morbidity and mortality; however, the underlying cellular and molecular mechanisms are not well understood. There is consensus that the underlying mechanism(s) resulting in pre-eclampsia is centered around abnormal placentation, inadequate spiral-artery remodeling, and deficiency in trophoblast invasion, resulting in impaired maternal blood flow to the placenta and a release of signals and/or inflammatory mediators into maternal circulation triggering the systemic manifestations of pre-eclampsia. ER stress, resulting in impaired autophagy and placental release of aggregated proteins, may also confer systemic stress to maternal organs in pre-eclampsia. Extracellular vesicles (EVs), lipid-bilayer enclosed structures containing macromolecules including proteins, miRNA, and other important nucleotides, have been suggested to play an important role in this maternal-fetal communication. Circulating EVs are present in greater quantity in the plasma of pre-eclampsia subjects compared to normal pregnancy, and the placental derived EVs have been shown to have altered protein and RNA cargo. In this review, we will focus on EVs and their role in pre-eclampsia, specifically their role in immune responses, inflammation, altered angiogenesis, and endothelial dysfunction.

Characterizing Extracellular Vesicles and Their Diverse RNA Contents

Cells release nanometer-scale, lipid bilayer-enclosed biomolecular packages (extracellular vesicles; EVs) into their surrounding environment. EVs are hypothesized to be intercellular communication agents that regulate physiological states by transporting biomolecules between near and distant cells. The research community has consistently advocated for the importance of RNA contents in EVs by demonstrating that: (1) EV-related RNA contents can be detected in a liquid biopsy, (2) disease states significantly alter EV-related RNA contents, and (3) sensitive and specific liquid biopsies can be implemented in precision medicine settings by measuring EV-derived RNA contents. Furthermore, EVs have medical potential beyond diagnostics. Both natural and engineered EVs are being investigated for therapeutic applications such as regenerative medicine and as drug delivery agents. This review focuses specifically on EV characterization, analysis of their RNA content, and their functional implications. The NIH extracellular RNA communication (ERC) program has catapulted human EV research from an RNA profiling standpoint by standardizing the pipeline for working with EV transcriptomics data, and creating a centralized database for the scientific community. There are currently thousands of RNA-sequencing profiles hosted on the Extracellular RNA Atlas alone (Murillo et al., 2019), encompassing a variety of human biofluid types and health conditions. While a number of significant discoveries have been made through these studies individually, integrative analyses of these data have thus far been limited. A primary focus of the ERC program over the next five years is to bring higher resolution tools to the EV research community so that investigators can isolate and analyze EV sub-populations, and ultimately single EVs sourced from discrete cell types, tissues, and complex biofluids. Higher resolution techniques will be essential for evaluating the roles of circulating EVs at a level which impacts clinical decision making. We expect that advances in microfluidic technologies will drive near-term innovation and discoveries about the diverse RNA contents of EVs. Long-term translation of EV-based RNA profiling into a mainstay medical diagnostic tool will depend upon identifying robust patterns of circulating genetic material that correlate with a change in health status.

Transfection of maternal cells with placental extracellular vesicles in preeclampsia

The role of extracellular vesicles is widely studied. As well as other organs, placenta produces extracellular vesicles during both, normal and pathological pregnancies. During pregnancy, placental/fetal free DNA circulates in maternal blood. Concentrations of free placental DNA are much higher when pregnancy complications of various etiologies occur. Such a complication could be preeclampsia. In our previous animal model, administration of pure DNA isolated from fetus did not induce any prenatal complications. Here we hypothesize that in real life during preeclampsia or other pregnancy complications, placental DNA might be transported by extracellular vesicles to maternal cells. Also, our preliminary data prove that placental DNA is present in circulating exosomes in maternal blood. Therefore, a lipid bilayer of extracellular vesicles could protect DNA from degradation by enzymes. Extracellular vesicles tend to merge with other cells, therefore, following expression of fetal genes from placental extracellular vesicles in maternal cells could lead to an immune response already observed in pregnancy complications. Future studies should be mainly focused on verification of our hypothesis and evaluate the potential of placental/fetal extracellular vesicles and their gene transfer in preeclampsia or other pregnancy complications.

Unique microRNA Signals in Plasma Exosomes from Pregnancies Complicated by Preeclampsia

Although preeclampsia is a common and serious complication of pregnancy, insight into its pathobiology and diagnosis is lacking. Circulating plasma exosomes, which contain RNA and other molecules and have recently become accessible for diagnostics, may be informative in this regard. We tested the hypothesis that preeclampsia may affect the miRNA cargo within circulating maternal blood exosomes. We collected plasma from 60 pregnant women at term, including 20 women with pregnancy complicated by preeclampsia, and 20 women with fetal growth restriction and 20 with healthy pregnancy, serving as controls. We isolated exosomes from the maternal plasma by continuous density gradient ultracentrifugation. Our main outcome variable was exosomal miRNA cargo, analyzed by quantitative polymerase chain reaction-based TaqMan advanced miRNA assay in a card format and the expression of differentially expressed exosomal miRNA in whole plasma from the same participants. We found that 7 miRNA species were differentially expressed in exosomes from women with preeclampsia and those from controls. In contrast, there was no significant difference in exosomal miRNA expression between women with fetal growth restriction and controls. The results were not affected by fetal sex. Only one of the preeclampsia-related, differentially expressed exosomal miRNAs was significantly different in whole plasma miRNA analysis. We concluded that unlike whole plasma miRNA, exosomes extracted from the plasma of women with preeclampsia exhibit a unique miRNA profile, suggesting that plasma exosomal miRNA could provide insight into the pathophysiology of preeclampsia, and may play a role in disease diagnostics.

Cell-Free Nucleic Acids

The discovery of cell-free DNA (cfDNA) dates back to 1948, when Mandel and Metais found it in the sera of cancer patients [...].

[A review on muscle-specific microRNAs as the biomarker for Duchenne muscular dystrophy]

MicroRNA (miRNA) is a non-coding single-stranded RNA with a length of approximately 22 nucleotides and is mainly responsible for the regulation of gene expression at the post-transcriptional level. At present, miRNA have become potential biomarkers for various diseases such as tumor, leukemia, and nervous system disease. Muscle-specific microRNAs are enriched in the skeletal muscle of patients with Duchenne muscular dystrophy (DMD) and also play an important role in the pathogenesis of DMD. Creatine kinase has limited specificity in the diagnosis of DMD since its level is not significantly associated with disease severity, and therefore, it is of great clinical significance to explore whether muscle-specific microRNAs can be used as ideal biomarkers for DMD. This article reviews the research advances in this field.

Molecular Targets of Aspirin and Prevention of Preeclampsia and Their Potential Association with Circulating Extracellular Vesicles during Pregnancy

Uncomplicated healthy pregnancy is the outcome of successful fertilization, implantation of embryos, trophoblast development and adequate placentation. Any deviation in these cascades of events may lead to complicated pregnancies such as preeclampsia (PE). The current incidence of PE is 2–8% in all pregnancies worldwide, leading to high maternal as well as perinatal mortality and morbidity rates. A number of randomized controlled clinical trials observed the association between low dose aspirin (LDA) treatment in early gestational age and significant reduction of early onset of PE in high-risk pregnant women. However, a substantial knowledge gap exists in identifying the particular mechanism of action of aspirin on placental function. It is already established that the placental-derived exosomes (PdE) are present in the maternal circulation from 6 weeks of gestation, and exosomes contain bioactive molecules such as proteins, lipids and RNA that are a “fingerprint” of their originating cells. Interestingly, levels of exosomes are higher in PE compared to normal pregnancies, and changes in the level of PdE during the first trimester may be used to classify women at risk for developing PE. The aim of this review is to discuss the mechanisms of action of LDA on placental and maternal physiological systems including the role of PdE in these phenomena. This review article will contribute to the in-depth understanding of LDA-induced PE prevention.

The role of epigenetic changes in preeclampsia

Preeclampsia (PE) is a disorder affecting 2-10% of pregnancies and has a major role for perinatal and maternal mortality and morbidity. PE can be occurred by initiation of new hypertension combined with proteinuria after 20 weeks gestation, as well as various reasons such as inflammatory cytokines, poor trophoblast invasion can be related with PE disease. Environmental factors can cause epigenetic changes including DNA methylation, microRNAs (miRNAs), and histone modification that may be related to different diseases such as PE. Abnormal DNA methylation during placentation is the most important epigenetic factor correlated with PE. Moreover, changes in histone modification like acetylation and also the effect of overregulation or low regulation of miRNAs or long noncoding RNAs on variety signaling pathways can be resulted in PE. The aim of this review is to describe of studies about epigenetic changes in PE and its therapeutic strategies.

Role of the Monocyte-Macrophage System in Normal Pregnancy and Preeclampsia

The proper functioning of the monocyte-macrophage system, an important unit of innate immunity, ensures the normal course of pregnancy. In this review, we present the current data on the origin of the monocyte-macrophage system and its functioning in the female reproductive system during the ovarian cycle, and over the course of both normal and complicated pregnancy. Preeclampsia is a crucial gestation disorder characterized by pronounced inflammation in the maternal body that affects the work of the monocyte-macrophage system. The effects of inflammation at preeclampsia manifest in changes in monocyte counts and their subset composition, and changes in placental macrophage counts and their polarization. Here we summarize the recent data on this issue for both the maternal organism and the fetus. The influence of estrogen on macrophages and their altered levels in preeclampsia are also discussed.

Surface-Functionalized Nanoparticles as Efficient Tools in Targeted Therapy of Pregnancy Complications

Minimizing exposure of the fetus to medication and reducing adverse off-target effects in the mother are the primary challenges in developing novel drugs to treat pregnancy complications. Nanomedicine has introduced opportunities for the development of novel platforms enabling targeted delivery of drugs in pregnancy. This review sets out to discuss the advances and potential of surface-functionalized nanoparticles in the targeted therapy of pregnancy complications. We first describe the human placental anatomy, which is fundamental for developing placenta-targeted therapy, and then we review current knowledge of nanoparticle transplacental transport mechanisms. Meanwhile, recent surface-functionalized nanoparticles for targeting the uterus and placenta are examined. Indeed, surface-functionalized nanoparticles could help prevent transplacental passage and promote placental-specific drug delivery, thereby enhancing efficacy and improving safety. We have achieved promising results in targeting the placenta via placental chondroitin sulfate A (plCSA), which is exclusively expressed in the placenta, using plCSA binding peptide (plCSA-BP)-decorated nanoparticles. Others have also focused on using placenta- and uterus-enriched molecules as targets to deliver therapeutics via surface-functionalized nanoparticles. Additionally, we propose that placenta-specific exosomes and surface-modified exosomes might be potential tools in the targeted therapy of pregnancy complications. Altogether, surface-functionalized nanoparticles have great potential value as clinical tools in the targeted therapy of pregnancy complications.

Quantification of circulating miR-517c-3p and miR-210-3p levels in preeclampsia

MicroRNAs (miRNAs, miRs) are small regulatory non-coding RNAs that regulate gene expression by incomplete complementary attachment to the 3'UTR, 5'UTR, ORF and promoter regions of target mRNAs. We compared plasma levels of miR-210-3p and miR-517c-3p as cell-free microRNAs (cfmiRNAs) in preeclamptic (n = 20) and healthy women (n = 20). These miRs are responsible for cell growth and proliferation, placental hypoxia, immune response and apoptosis. We found higher expression levels of miR-210 and miR-517c in preeclamptic cases (+3.34 and +2.27 fold change, respectively). This is the first study that evaluates the plasma levels of miR-517c in preeclamptic cases by real time PCR (RT-PCR) technique. This study can lead to new opportunities for research about the roles of miRNAs in preeclampsia etiology or new biomarkers.

Causes and Consequences of the Dysregulated Maternal Renin-Angiotensin System in Preeclampsia

A healthy pregnancy outcome depends on the activation of the renin-angiotensin-aldosterone system (RAAS) as a regulated, integrated response to the growing demands of the conceptus. Both the circulating RAAS and the intrarenal renin-angiotensin system (iRAS) play major roles in cardiovascular function and fluid and electrolyte homeostasis. The circulating RAAS becomes dysfunctional in preeclampsia and we propose that dysregulation of the iRAS plays a role in development of the clinical syndrome known as preeclampsia. Experimental studies in animals have shown that placental renin, when released into the maternal circulation, can cause hypertension. We postulate that abnormal placental development is associated with over-secretion of renin and other RAS proteins/angiotensin (Ang) peptides by the placenta/decidua into the maternal circulation. We hypothesise that this is because of increased shedding of exosomes and other placental particles into the maternal circulation that not only contain RAS proteins and peptides but also microRNAs (miRNAs) that target RAS mRNAs, and Ang II type 1 receptor autoantibodies (AT₁R-AAs), that are agonists for, and have the same actions as, Ang II. As a result, there is both suppression of the circulating RAAS that is responsible for maintaining maternal homeostasis and activation of the iRAS. Together with altered vascular reactivity to Ang peptides, the iRAS causes hypertension, renal damage and secondary changes in the neurohumoral control of the maternal circulation and fluid and electrolyte balance, which contribute to the pathophysiology of preeclampsia.