Amnion-Epithelial-Cell-Derived Exosomes Demonstrate Physiologic State of Cell under Oxidative Stress

High-Throughput 3D-Printed Model of the Feto-Maternal Interface for the Discovery and Development of Preterm Birth Therapies

Spontaneous preterm birth (PTB) affects around 11% of births, posing significant risks to neonatal health due to the inflammation at the fetal-maternal interface (FMi). This inflammation disrupts immune tolerance during pregnancy, often leading to PTB. While organ-on-a-chip (OOC) devices effectively mimic the physiology, pathophysiology, and responses of FMi, their relatively low throughput limits their utility in high-throughput testing applications. To overcome this, we developed a three-dimensional (3D)-printed model that fits in a well of a 96-well plate and can be mass-produced while also accurately replicating FMi, enabling efficient screening of drugs targeting FMi inflammation. Our model features two cell culture chambers (maternal and fetal cells) interlinked via an array of microfluidic channels. It was thoroughly validated, ensuring cell viability, metabolic activity, and cell-specific markers. The maternal chamber was exposed to lipopolysaccharides (LPS) to induce an inflammatory state, and proinflammatory cytokines in the culture supernatant were quantified. Furthermore, the efficacy of anti-inflammatory inhibitors in mitigating LPS-induced inflammation was investigated. Results demonstrated that our model supports robust cell growth, maintains viability, and accurately mimics PTB-associated inflammation. This high-throughput 3D-printed model offers a versatile platform for drug screening, promising advancements in drug discovery and PTB prevention.

Stretch Causes cffDNA and HMGB1-Mediated Inflammation and Cellular Stress in Human Fetal Membranes

Danger-associated molecular patterns (DAMPs) are elevated within the amniotic cavity, and their increases correlate with advancing gestational age, chorioamnionitis, and labor. Although the specific triggers for their release in utero remain unclear, it is thought that they may contribute to the initiation of parturition by influencing cellular stress mechanisms that make the fetal membranes (FMs) more susceptible to rupture. DAMPs induce inflammation in many different tissue types. Indeed, they precipitate the subsequent release of several proinflammatory cytokines that are known to be key for the weakening of FMs. Previously, we have shown that in vitro stretch of human amnion epithelial cells (hAECs) induces a cellular stress response that increases high-mobility group box-1 (HMGB1) secretion. We have also shown that cell-free fetal DNA (cffDNA) induces a cytokine response in FM explants that is fetal sex-specific. Therefore, the aim of this work was to further investigate the link between stretch and the DAMPs HMGB1 and cffDNA in the FM. These data show that stretch increases the level of cffDNA released from hAECs. It also confirms the importance of the sex of the fetus by demonstrating that female cffDNA induced more cellular stress than male fetuses. Our data treating hAECs and human amnion mesenchymal cells with HMGB1 show that it has a differential effect on the ability of the cells of the amnion to upregulate the proinflammatory cytokines and propagate a proinflammatory signal through the FM that may weaken it. Finally, our data show that sulforaphane (SFN), a potent activator of Nrf2, is able to mitigate the proinflammatory effects of stretch by decreasing the levels of HMGB1 release and ROS generation after stretch and modulating the increase of key cytokines after cell stress. HMGB1 and cffDNA are two of the few DAMPs that are known to induce cytokine release and matrix metalloproteinase (MMP) activation in the FMs; thus, these data support the general thesis that they can function as potential central players in the normal mechanisms of FM weakening during the normal distension of this tissue at the end of a normal pregnancy.

Are fetal microchimerism and circulating fetal extracellular vesicles important links between spontaneous preterm delivery and maternal cardiovascular disease risk?

Trafficking and persistence of fetal microchimeric cells (fMCs) and circulating extracellular vesicles (EVs) have been observed in animals and humans, but their consequences in the maternal body and their mechanistic contributions to maternal physiology and pathophysiology are not yet fully defined. Fetal cells and EVs may help remodel maternal organs after pregnancy-associated changes, but the cell types and EV cargos reaching the mother in preterm pregnancies after exposure to various risk factors can be distinct from term pregnancies. As preterm delivery-associated maternal complications are rising, revisiting this topic and formulating scientific questions for future research to reduce the risk of maternal morbidities are timely. Epidemiological studies report maternal cardiovascular risk as one of the major complications after preterm delivery. This paper suggests a potential link between fMCs and circulating EVs and adverse maternal cardiovascular outcomes post-pregnancies, the underlying mechanisms, consequences, and methods for and how this link might be assessed.

EGF-conditioned M1 macrophages Convey reduced inflammation into corneal endothelial cells through exosomes

Epidermal Growth Factor (EGF), a protein pivotal in cell proliferation and survival, has recently shown promise in alleviating inflammation. This study investigates EGF's impact on M1 macrophages, exploring its potential for anti-inflammatory and anti-vasculogenic interactions with corneal endothelial cells (CECs). Polarized M1 macrophages treated with EGF exhibited a suppression of gene expressions related to inflammatory and vasculogenic signals. The anti-inflammatory effects of EGF were observed in co-culture systems with human CECs (HCECs), showcasing its ability to alter macrophage phenotypes. Exosomes derived from EGF-treated M1 macrophages demonstrated enriched proteomic profiles related to immune system regulation and inflammation inhibition. When applied as eye drops in murine corneas, EGF-conditioned M1 macrophage-derived exosomes effectively reduced inflammation and increased M2-related ARG1 expression. This study highlights EGF's potential in mitigating inflammation in M1 macrophages and its delivery through exosomes to cultured HCECs and murine corneas, suggesting a novel therapeutic avenue for ocular surface anti-inflammatory treatments.

IFPA Joan Hunt Senior Award in Placentology lecture: Extracellular vesicle signalling and pregnancy

The field of extracellular vesicle (EV) signalling has the potential to transform our understanding of maternal-fetal communication and affords new opportunities for non-invasive prenatal testing and therapeutic intervention. EVs have been implicated in implantation, placentation, maternal adaptation to pregnancy and complications of pregnancy, being detectable in maternal circulation as early as 6 weeks of pregnancy. EVs of differing biogenic origin, composition and bioactivity are released by cells to maintain homoeostasis. Induction of EV signalling is associated with aberrant cellular metabolism and manifests as changes in EV concentrations and/or composition. Characterizing such changes affords opportunity to develop more informative diagnostics and efficacious interventions. To develop accurate and reliable EV-based diagnostics requires: identification of disease-associated biomarkers in specific EV subpopulations; and rapid, reproducible and scalable sample processing. Conventional isolation methods face challenges due to co-isolation of particles with similar physicochemical properties. Methods targeting specific vesicle-surface epitopes and compatible with automated platforms show promise. Effective EV therapeutics require precise targeting, achieved through genetic engineering to release EVs expressing cell-targeting ligands and carrying therapeutic payloads. Unlike cell-based therapies, this approach offers advantages including: low immunogenicity; stability; and long-term storage. Although EV diagnostics and therapeutics in reproductive biology are nascent, available technologies can enhance our understanding of EV signalling between mother and fetus, its role in pregnancies and improve outcomes.

Extracellular vesicles from mouse trophoblast cells: Effects on neural progenitor cells and potential participants in the placenta-brain axis†

The fetal brain of the mouse is thought to be dependent upon the placenta as a source of serotonin (5-hydroxytryptamine; 5-HT) and other factors. How factors reach the developing brain remains uncertain but are postulated here to be part of the cargo carried by placental extracellular vesicles (EV). We have analyzed the protein, catecholamine, and small RNA content of EV from mouse trophoblast stem cells (TSC) and TSC differentiated into parietal trophoblast giant cells (pTGC), potential primary purveyors of 5-HT. Current studies examined how exposure of mouse neural progenitor cells (NPC) to EV from either TSC or pTGC affect their transcriptome profiles. The EV from trophoblast cells contained relatively high amounts of 5-HT, as well as dopamine and norepinephrine, but there were no significant differences between EV derived from pTGC and from TSC. Content of miRNA and small nucleolar (sno)RNA, however, did differ according to EV source, and snoRNA were upregulated in EV from pTGC. The primary inferred targets of the microRNA (miRNA) from both pTGC and TSC were mRNA enriched in the fetal brain. NPC readily internalized EV, leading to changes in their transcriptome profiles. Transcripts regulated were mainly ones enriched in neural tissues. The transcripts in EV-treated NPC that demonstrated a likely complementarity with miRNA in EV were mainly up- rather than downregulated, with functions linked to neuronal processes. Our results are consistent with placenta-derived EV providing direct support for fetal brain development and being an integral part of the placenta-brain axis.

Group B streptococcus induces cellular senescence in human amnion epithelial cells through a partial interleukin-1-mediated mechanism

Group B streptococcus (GBS) infection is a significant public health concern associated with adverse pregnancy complications and increased neonatal mortality and morbidity. However, the mechanisms underlying the impact of GBS on the fetal membrane, the first line of defense against pathogens, are not fully understood. Here, we propose that GBS induces senescence and inflammatory factors (IL-6 and IL-8) in the fetal membrane through interleukin-1 (IL-1). Utilizing the existing transcriptomic data on GBS-exposed human fetal membrane, we showed that GBS affects senescence-related pathways and genes. Next, we treated primary amnion epithelial cells with conditioned medium from the choriodecidual layer of human fetal membrane exposed to GBS (GBS collected choriodecidual [CD] conditioned medium) in the absence or presence of an IL-1 receptor antagonist (IL-1Ra). GBS CD conditioned medium significantly increased β-galactosidase activity, IL-6 and IL-8 release from the amnion epithelial cells. Cotreatment with IL1Ra reduced GBS-induced β-galactosidase activity and IL-6 and IL-8 secretion. Direct treatment with IL-1α or IL-1β confirmed the role of IL-1 signaling in the regulation of senescence in the fetal membrane. We further showed that GBS CD conditioned medium and IL-1 decreased cell proliferation in amnion epithelial cells. In summary, for the first time, we demonstrate GBS-induced senescence in the fetal membrane and present evidence of IL-1 pathway signaling between the choriodecidua and amnion layer of fetal membrane in a paracrine manner. Further studies will be warranted to understand the pathogenesis of adverse pregnancy outcomes associated with GBS infection and develop therapeutic interventions to mitigate these complications.

The Truth Is Out There: Biological Features and Clinical Indications of Extracellular Vesicles from Human Perinatal Stem Cells

The potential of perinatal tissues to provide cellular populations to be used in different applications of regenerative medicine is well established. Recently, the efforts of researchers are being addressed regarding the evaluation of cell products (secreted molecules or extracellular vesicles, EVs) to be used as an alternative to cellular infusion. The data regarding the effective recapitulation of most perinatal cells' properties by their secreted complement point in this direction. EVs secreted from perinatal cells exhibit key therapeutic effects such as tissue repair and regeneration, the suppression of inflammatory responses, immune system modulation, and a variety of other functions. Although the properties of EVs from perinatal derivatives and their significant potential for therapeutic success are amply recognized, several challenges still remain that need to be addressed. In the present review, we provide an up-to-date analysis of the most recent results in the field, which can be addressed in future research in order to overcome the challenges that are still present in the characterization and utilization of the secreted complement of perinatal cells and, in particular, mesenchymal stromal cells.

Flip a coin: cell senescence at the maternal-fetal interface†

During pregnancy, cell senescence at the maternal-fetal interface is required for maternal well-being, placental development, and fetal growth. However, recent reports have shown that aberrant cell senescence is associated with multiple pregnancy-associated abnormalities, such as preeclampsia, fetal growth restrictions, recurrent pregnancy loss, and preterm birth. Therefore, the role and impact of cell senescence during pregnancy requires further comprehension. In this review, we discuss the principal role of cell senescence at the maternal-fetal interface, emphasizing its "bright side" during decidualization, placentation, and parturition. In addition, we highlight the impact of its deregulation and how this "dark side" promotes pregnancy-associated abnormalities. Furthermore, we discuss novel and less invasive therapeutic practices associated with the modulation of cell senescence during pregnancy.

Development of oxidative stress-associated disease models using feto-maternal interface organ-on-a-chip

Oxidative stress (OS) and inflammation arising from cellular derangements at the fetal membrane-decidual interface (feto-maternal interface [FMi]) is a major antecedent to preterm birth (PTB). However, it is impractical to study OS-associated FMi disease state during human pregnancy, and thus it is difficult to develop strategies to reduce the incidences of PTB. A microfluidic organ-on-chip model (FMi-OOC) that mimics the in vivo structure and functions of FMi in vitro was developed to address this challenge. The FMi-OOC contained fetal (amnion epithelial, mesenchymal, and chorion) and maternal (decidua) cells cultured in four compartments interconnected by arrays of microchannels to allow independent but interconnected co-cultivation. Using this model, we tested the effects of OS and inflammation on both fetal (fetal → maternal) and maternal (maternal → fetal) sides of the FMi and determined their differential impact on PTB-associated pathways. OS was induced using cigarette smoke extract (CSE) exposure. The impacts of OS were assessed by measuring cell viability, disruption of immune homeostasis, epithelial-to-mesenchymal transition (EMT), development of senescence, and inflammation. CSE propagated (LC/MS-MS analysis for nicotine) over a 72-hour period from the maternal to fetal side, or vice versa. However, they caused two distinct pathological effects on the maternal and fetal cells. Specifically, fetal OS induced cellular pathologies and inflammation, whereas maternal OS caused immune intolerance. The pronounced impact produced by the fetus supports the hypothesis that fetal inflammatory response is a mechanistic trigger for parturition. The FMi disease-associated changes identified in the FMi-OOC suggest the unique capability of this in vitro model in testing in utero conditions.

Mitigating Oxidative Stress in Perinatal Cells: A Critical Step toward an Optimal Therapeutic Use in Regenerative Medicine

Oxidative stress (OS) occurs when the production of reactive oxygen species (ROS) is not balanced by the body's antioxidant defense system. OS can profoundly affect cellular health and function. ROS can have a profound negative impact on cells that undergo a predestined and time-regulated process of proliferation or differentiation, such as perinatal stem cells. Due to the large-scale employment of these immunotolerant stem cells in regenerative medicine, it is important to reduce OS to prevent them from losing function and increase their application in the regenerative medicine field. This goal can be achieved through a variety of strategies, such as the use of antioxidants and other compounds that can indirectly modulate the antioxidant defense system by enhancing cellular stress response pathways, including autophagy and mitochondrial function, thereby reducing ROS levels. This review aims to summarize information regarding OS mechanisms in perinatal stem cells and possible strategies for reducing their deleterious effects.

A Microphysiological Device to Model the Choriodecidual Interface Immune Status during Pregnancy

During human pregnancy the chorion (fetal) lines decidua (maternal) creating the feto-maternal interface. Despite their proximity, resident decidual immune cells remain quiescent during gestation and do not invade the chorion. Infection and infiltration of activated immune cells toward the chorion are often associated with preterm birth. However, the mechanisms that maintain choriodecidual immune homeostasis or compromise immune barrier functions remain unclear. To understand these processes, a two-chamber microphysiological system (MPS) was created to model the human choriodecidual immune interface under normal and infectious conditions in vitro. This MPS has outer (fetal chorion trophoblast cells) and inner chambers (maternal decidual + CD45+ cells [70:30 ratio]) connected by microchannels. Decidual cells were treated with LPS to mimic maternal infection, followed by immunostaining for HLA-DR and HLA-G, immune panel screening by imaging cytometry by time of flight, and immune regulatory factors IL-8 and IL-10, soluble HLA-G, and progesterone (ELISA). LPS induced a proinflammatory phenotype in the decidua characterized by a decrease in HLA-DR and an increase in IL-8 compared with controls. LPS treatment increased the influx of immune cells into the chorion, indicative of chorionitis. Cytometry by time of flight characterized immune cells in both chambers as active NK cells and neutrophils, with a decrease in the abundance of nonproinflammatory cytokine-producing NK cells and T cells. Conversely, chorion cells increased progesterone and soluble HLA-G production while maintaining HLA-G expression. These results highlight the utility of MPS to model choriodecidual immune cell infiltration and determine the complex maternal-fetal crosstalk to regulate immune balance during infection.

The Role of Fetal Membranes during Gestation, at Term, and Preterm Labor

During pregnancy, the fetal membranes (i.e., amniochorionic membranes) surround the intrauterine cavity and provide mechanical, immune, and endocrine support to protect the fetus. Though they are a vital component of the intrauterine cavity, the fetal membranes are largely overlooked as an extension of the placenta, leading to a poor understanding of their role during gestation, parturition, or preterm birth. The fetal membranes are comprised of fetal cellular and stromal layers and line up with maternal decidua forming the feto-maternal interface during pregnancy. This interface plays a large role during pregnancy and the induction of term or preterm parturition (e.g., labor). Here we summarize the function of the fetal membranes focusing on their role during gestation at term, and during preterm births.

Silencing P38 MAPK reduces cellular senescence in human fetal chorion trophoblast cells

PROBLEM

Amniochorion senescence generates mechanistic signals to initiate parturition. Activation of p38 mitogen-activated kinase (MAPK) in fetal amnion cells is a key mediator of senescence as well as epithelial-mesenchymal transition (EMT) of amnion cells. However, the impact of p38 MAPK in chorion trophoblast cells (CTCs) is unclear. We tested if eliminating p38 will reduce oxidative stress (OS) induced cell fates like cellular senescence, EMT, and inflammation induced by these processes in CTCs.

METHODS

p38MAPK in CTCs was silenced using CRISPR/Cas9. OS was evoked by cigarette smoke extract (CSE) exposure. EMT was evoked by transforming growth factor (TGF)-ß treatment. Cell cycle, senescence, EMT, and inflammation were analyzed.

RESULTS

CSE-induced changes in the cell cycle were not seen in p38KO CTCs compared to WT cells. OS induced by CSE evoked senescence and senescence-associated secretory phenotype (SASP as indicated by IL-6 and IL-8 increase) in WT but not in p38MAPK KO CTCs. No changes were noted in HLA-G expression regardless of the status of p38MAPK. Neither CSE nor TGF-ß evoked EMT in either WT or p38 KO CTCs.

CONCLUSION

Senescence and senescence-associated inflammation in human fetal CTCs are mediated by p38MAPK. Compared to amnion epithelial cells, CTCs are resistant to EMT. This refractoriness may help them to maintain the barrier functions at the choriodecidual interface.

Adapting an organ-on-chip device to study the effect of fetal sex and maternal race/ethnicity on preterm birth related intraamniotic inflammation leading to fetal neuroinflammation

PROBLEM

Fetal neuroinflammation has been linked to preterm birth-related intraamniotic infection and inflammation; However, the contribution of fetal sex and maternal race/ethnicity is unknown. To determine if fetal sex and maternal race/ethnicity influence neuroinflammation, an organ-on-chip (OOC) model were established under normal or pathologic conditions utilizing amniotic fluid.

METHOD OF STUDY

OOC is composed of two-cell culture chambers connected by Type IV collagen-coated microchannels. Human fetal astroglia (SVGp12) and microglia (HMC3) were co-cultured at an 80:20 ratio in the inner chamber. The outer chamber contained amniotic fluid (AF) from male and female fetuses of White Hispanic (WH) and African-American (AA) pregnant women with or without lipopolysaccharide (LPS-100 ng/ml) and incubated for 48 h. Glial migration (brightfield microscopy), activation (Immunocytochemistry), and cytokine production (Luminex assays) were quantified and compared (N = 4 for each category of sex and race/ethnicity).

RESULTS

In a pooled analysis, AF+LPS did not induce glial activation or inflammatory changes compared to AF alone. When stratified by sex, male AF+LPS promoted significant glial activation (high CD11b:p < 0.05; low Iba1:p < 0.01) compared to male AF without LPS; however, this was not associated with changes in pro-inflammatory cytokines. When stratified by race/ethnicity, AF+LPS induced glial activation in both groups, but a differential increase in pro-inflammatory cytokines was seen between WH and AA AF (WH-interleukin-1β: p < 0.05; AA-interleukin-8: p < 0.01).

CONCLUSION

This OOC model of fetal neuroinflammation has determined that race/ethnicity differences do exist for perinatal brain injury. The fetal sex of neonates was not a determining factor of susceptibility to intraamniotic inflammation leading to neuroinflammation.

Stress signaler p38 mitogen-activated kinase activation: a cause for concern?

Oxidative stress (OS) induced activation of p38 mitogen-activated kinase (MAPK) and cell fate from p38 signaling was tested using the human fetal membrane's amnion epithelial cells (AEC). We created p38 KO AEC using the CRISPR/Cas9 approach and tested cell fate in response to OS on an AEC-free fetal membrane extracellular matrix (ECM). Screening using image CyTOF indicated OS causing epithelial-mesenchymal transition (EMT). Further testing revealed p38 deficiency prevented AEC senescence, EMT, cell migration, and inflammation. To functionally validate in vitro findings, fetal membrane-specific conditional KO (cKO) mice were developed by injecting Cre-recombinase encoded exosomes intra-amniotically into p38αloxP/loxP mice. Amnion membranes from p38 cKO mice had reduced senescence, EMT, and increased anti-inflammatory IL-10 compared with WT animals. Our study suggested that overwhelming activation of p38 in response to OS inducing risk exposures can have an adverse impact on cells, cause cell invasion, inflammation, and ECM degradation detrimental to tissue homeostasis.

Testing of drugs using human feto-maternal interface organ-on-chips provide insights into pharmacokinetics and efficacy

Objectives: To improve preclinical drug testing during pregnancy, we developed multiple microfluidic organ-on-chip (OOC) devices that represent the structure, functions, and responses of the two feto-maternal interfaces (FMis) in humans (fetal membrane [FMi-OOC] and placenta [PLA-OOC]). This study utilized feto-maternal interface OOCs to test the kinetics and efficacy of drugs during pregnancy. Study design: The FMi-OOC contained amnion epithelial, mesenchymal, chorion trophoblast, and decidual cells. The PLA-OOC contained cytotrophoblasts (BeWo), syncytiotrophoblasts (BeWo + forskolin), and human umbilical vein endothelial cell lines. Therapeutic concentrations of either pravastatin or rosuvastatin (200 ng mL^-1), a model drug for these experiments, were applied to either decidua (in FMi-OOC) and syncytiotrophoblasts (in PLA-OOC) chambers under normal and oxidative stress conditions (induced by cigarette smoke extract [CSE 1 : 25]) to evaluate maternal drug exposure during normal pregnancy or oxidative stress (OS) associated pathologies, respectively. We determined statin pharmacokinetics and metabolism (LC-MS/MS), drug-induced cytotoxicity (LDH assay), and efficacy to reduce OS-induced inflammation (multiplex cytokine assay). Results: Both OOCs mimicked two distinct human feto-maternal interfaces. The drugs tested permeated the maternal-fetal cell layers of the FMi-OOC and PLA-OOC within 4 hours and generated cell and time-specific statin metabolites from various cell types without causing any cytotoxicity. OS-induced pro-inflammatory cytokines were effectively reduced by statins by increasing anti-inflammatory cytokine response across the FMi-OOC and PLA-OOC. Conclusion: Two distinct feto-maternal interface OOCs were developed, tested, and validated for their utility to conduct preclinical trials during pregnancy. We demonstrated that the placenta and fetal membranes-decidual interface both are able to transport and metabolize drugs and that the safety and efficacy of a drug can be determined using the anatomical structures recreated on OOCs.

Spontaneous preterm birth: Involvement of multiple feto-maternal tissues and organ systems, differing mechanisms, and pathways

Survivors of preterm birth struggle with multitudes of disabilities due to improper in utero programming of various tissues and organ systems contributing to adult-onset diseases at a very early stage of their lives. Therefore, the persistent rates of low birth weight (birth weight < 2,500 grams), as well as rates of neonatal and maternal morbidities and mortalities, need to be addressed. Active research throughout the years has provided us with multiple theories regarding the risk factors, initiators, biomarkers, and clinical manifestations of spontaneous preterm birth. Fetal organs, like the placenta and fetal membranes, and maternal tissues and organs, like the decidua, myometrium, and cervix, have all been shown to uniquely respond to specific exogenous or endogenous risk factors. These uniquely contribute to dynamic changes at the molecular and cellular levels to effect preterm labor pathways leading to delivery. Multiple intervention targets in these different tissues and organs have been successfully tested in preclinical trials to reduce the individual impacts on promoting preterm birth. However, these preclinical trial data have not been effectively translated into developing biomarkers of high-risk individuals for an early diagnosis of the disease. This becomes more evident when examining the current global rate of preterm birth, which remains staggeringly high despite years of research. We postulate that studying each tissue and organ in silos, as how the majority of research has been conducted in the past years, is unlikely to address the network interaction between various systems leading to a synchronized activity during either term or preterm labor and delivery. To address current limitations, this review proposes an integrated approach to studying various tissues and organs involved in the maintenance of normal pregnancy, promotion of normal parturition, and more importantly, contributions towards preterm birth. We also stress the need for biological models that allows for concomitant observation and analysis of interactions, rather than focusing on these tissues and organ in silos.

Exosomes in the f ield of reproduction: A scientometric study and visualization analysis

Background: The diagnostic capabilities of exosomes in the field of reproductive biomedicine have attracted much attention. The aim of this scientometric study was to statistically and qualitatively assess the knowledge structure, hot issues, and research trends of papers about exosomes in the field of reproduction using visualization methods.

Methods: The Web of Science Core Collection was searched for studies on exosomes in the field of reproduction. We performed bibliometric and visual analyses using VOSviewer, CiteSpace, and Microsoft Excel.

Results: After database search, 1,011 articles were included, with number of studies being published every year continually increasing. These publications came from 61 nations or regions, with the US having the highest number. The University of Queensland was the main institution in which the research was conducted. The journal Placenta contained the highest number studies. There were 5,247 authors in total. Carlos Salomon had the highest number of papers with co-citations. Exosomes, extracellular vesicles, pregnancy, microRNAs, preeclampsia, placenta, microvesicles, gene expression, biomarkers, and first trimester were the most frequently used terms.

Conclusion: Exosome research is booming in reproductive biomedicine. Future studies will likely focus on exosomes as biomarkers in gamete formation and fertilization, pregnancy, and cancers associated with reproduction. In addition to focusing on fundamental research, we should concentrate on the application of the results and the investigation of exosomes in infertile patients.

Leveraging bioengineering to assess cellular functions and communication within human fetal membranes

The fetal membranes enclose the growing fetus and amniotic fluid. Preterm prelabor rupture of fetal membranes is a leading cause of preterm birth. Fetal membranes are composed of many different cell types, both structural and immune. These cells must coordinate functions for tensile strength and membrane integrity to contain the growing fetus and amniotic fluid. They must also balance immune responses to pathogens with maintaining maternal-fetal tolerance. Perturbation of this equilibrium can lead to preterm premature rupture of membranes without labor. In this review, we describe the formation of the fetal membranes to orient the reader, discuss some of the common forms of communication between the cell types of the fetal membranes, and delve into the methods used to tease apart this paracrine signaling within the membranes, including emerging technologies such as organ-on-chip models of membrane immunobiology.

Fetal DNA Causes Sex-Specific Inflammation From Human Fetal Membranes

Inflammation is central to the mechanisms of parturition, but the lack of understanding of how it is controlled in normal parturition hampers our ability to understand how it may diverge resulting in preterm birth. Cell-free fetal DNA is found in the amniotic fluid, and it is thought to be able to activate inflammation as a danger-associated molecular pattern. Although its levels increases with gestational age, its effect has not been studied on the human fetal membranes. Thus, the aim of this study was to determine if the fetal DNA can trigger inflammation in the human fetal membranes and, thus, potentially contribute to the inflammatory load. Isolated human amniotic epithelial cells and fetal membrane explants were treated apically with fetal DNA causing the translocation of NF-KB into the nucleus of cells and throughout the cells of the explant layers with time. Fetal membrane explants were treated apically with either small or larger fragments of fetal DNA. IL-6, TNFα, and GM-CSF secretion was measured by ELISA, and pro-MMP2 and pro-MMP9 activity was measured by zymography from apical and basal media. Increased apical IL-6 secretion and basal pro-MMP2 activity was seen with small fragments of fetal DNA. When the data were disaggregated based on fetal sex, males had significant increases in IL-6 secretion and basal increased activity in pro-MMP2 and 9, whereas females had significantly increased basal secretion of TNFα. This was caused by the smaller fragments of fetal DNA, whereas the larger fragments did not cause any significant increases. Male fetal DNA had significantly lower percentages of methylation than females. Thus, when the cytokine and pro-MMP activity data were correlated with methylation percentage, IL-6 secretion significantly correlated negatively, whereas GM-CSF secretion positively correlated. These data support the role of fetal DNA as an inflammatory stimulus in the FM, as measured by increased NF-κB translocation, cytokine secretion, and increased pro-MMP activity. However, the data also suggested that the responses are different from FM tissues of male and female fetuses, and both the fragment size and methylation status of the fetal DNA can influence the magnitude and type of molecule secreted.

Actions of Bisphenol A on Different Feto-Maternal Compartments Contributing to Preterm Birth

Preterm birth remains to be one of the most prevalent obstetric complications worldwide. Since there are multiple etiological factors associated with this disease process, an integrative literature search in PubMed and Scopus databases on possible mechanism of action and effect of bisphenols on exposure on human or animal placental samples in preterm birth was conducted. From 2332 articles on initial literature search, 63 studies were included for full data extraction. Altogether, several pathways were shown to be possibly affected by bisphenols, leading to dysregulations in structural and endocrine foundation in the placenta, potential induction of senescence and failure of decidualization in the decidua, and possible propagation of inflammation in the fetal membranes. Combined, these actions may eventually counteract bisphenol-induced relaxation of the myometrium and promote contractility alongside fetal membrane weakening. In totality, these individual impairments in gestation-critical processes may lead to failure of maintenance of pregnancy, and thus effecting preterm birth.

Extra-nuclear histones: origin, significance and perspectives

Histones are classically known to organize the eukaryotic DNA into chromatin. They are one of the key players in regulating transcriptionally permissive and non-permissive states of the chromatin. Nevertheless, their context-dependent appearance within the cytoplasm and systemic circulation has also been observed. The past decade has also witnessed few scientific communications on the existence of vesicle-associated histones. Diverse groups have attempted to determine the significance of these extra-nuclear histones so far, with many of those studies still underway. Of note amongst these are interactions of extra-nuclear or free histones with cellular membranes, mediated by mutual cationic and anionic natures, respectively. It is here aimed to consolidate the mechanism of formation of extra-nuclear histones; implications of histone-induced membrane destabilization and explore the mechanisms of their association/release with extracellular vesicles, along with the functional aspects of these extra-nuclear histones in cell and systemic physiology.

Human Amniotic Epithelial Cells Secretome: Components, Bioactivity, and Challenges

Human amniotic epithelial cells (hAECs) derived from placental tissue have received significant attention as a promising tool in regenerative medicine. Several studies demonstrated their anti-inflammatory, anti-fibrotic, and tissue repair potentials. These effects were further shown to be retained in the conditioned medium of hAECs, suggesting their paracrine nature. The concept of utilizing the hAEC-secretome has thus evolved as a therapeutic cell-free option. In this article, we review the different components and constituents of hAEC-secretome and their influence as demonstrated through experimental studies in the current literature. Studies examining the effects of conditioned medium, exosomes, and micro-RNA (miRNA) derived from hAECs are included in this review. The challenges facing the application of this cell-free approach will also be discussed based on the current evidence.

Fetal Membranes Contribute to Drug Transport across the Feto-Maternal Interface Utilizing the Breast Cancer Resistance Protein (BCRP)

During pregnancy, the placenta is established as a primary organ for drug transport at the maternal-fetal interface. The fetal membranes (FM) also form an interface with maternal tissues; however, their role in drug transport has not been previously investigated. Knowledge of drug transport across this feto-maternal interface along with the placenta can improve new drug development and testing for use during pregnancy. We also hypothesize that extracellular vesicles (exosomes 30–160 nm) released from the FM and placental cells may also contain drug transport proteins and might impact drug trafficking across the feto-maternal interfaces. The objectives were to (1) localize the breast cancer resistance protein (BCRP) in human FM; (2) determine the drug transport function of BCRP in chorion trophoblast cells (CTCs) of the FM; and (3) investigate the presence of BCRP in FM cell-derived exosomes, as a paracrine modifier of the tissue environment for transport functions. The gene and protein expressions of ABCG2/BCRP in FMs were determined by quantitative real-time PCR (qRT-PCR) and western blotting (WB) and were localized by immunohistochemistry (IHC). The surface expression of BCRP in FM cells was determined by flow cytometry. The functional role of BCRP was assessed by an EFFLUX dye multidrug resistance assay. The presence of BCRP in exosomes derived from CTCs and BeWo cells was examined using ExoView^®. Data derived from CTCs are compared with placental trophoblast cells (BeWo). BCRP is expressed and localized in the fetal membrane, primarily in the chorion trophoblast cell layer and scarcely in the amnion epithelial layer (AEC), and primarily localized on both AEC and CTC cell surfaces. Efflux assay data showed that FM cells have similar drug resistance activity as BeWo cells, suggesting that FM also have drug transportation capabilities. BeWo- and CTC-derived exosomes expressed limited BCRP protein on the surface, so it was predominantly contained in the exosomal lumen. As far as we are aware, this is the first study to report BCRP expression in fetal membrane cells and as cargo in fetal membrane-derived exosomes. We report that fetal membrane cells are capable of drug transportation. Based on these results, investigational drug trials should include the FM and its exosomes as possible drug transportation routes in pregnancy.

Organic Anion Transporting Polypeptide 2B1 in Human Fetal Membranes: A Novel Gatekeeper for Drug Transport During Pregnancy?

Current intervention strategies have not been successful in reducing the risks of adverse pregnancy complications nor maternal and fetal morbidities associated with pregnancy complications. Improving pregnancy and neonatal outcomes requires a better understanding of drug transport mechanisms at the feto-maternal interfaces, specifically the placenta and fetal membrane (FM). The role of several solute carrier uptake transporter proteins (TPs), such as the organic anion transporting polypeptide 2B1 (OATP2B1) in transporting drug across the placenta, is well-established. However, the mechanistic role of FMs in this drug transport has not yet been elucidated. We hypothesize that human FMs express OATP2B1 and functions as an alternate gatekeeper for drug transport at the feto-maternal interface. We determined the expression of OATP2B1 in term, not-in-labor, FM tissues and human FM cells [amnion epithelial cell (AEC), chorion trophoblast cell (CTC), and mesenchymal cells] using western blot analyses and their localization using immunohistochemistry. Changes in OATP2B1 expression was determined for up to 48 h after stimulation with cigarette smoke extract (CSE), an inducer of oxidative stress. The functional role of OATP2B1 was determined by flow cytometry using a zombie violet dye substrate assay. After OATP2B1 gene silencing, its functional relevance in drug transport through the feto-maternal interface was tested using a recently developed feto-maternal interface organ-on-a-chip (OOC) system that contained both FM and maternal decidual cells. Propagation of a drug (Rosuvastatin, that can be transported by OATP2B1) within the feto-maternal interface OOC system was determined by mass spectrometry. FMs express OATP2B1 in the CTC and AEC layers. In FM explants, OATP2B1 expression was not impacted by oxidative stress. Uptake of the zombie violet dye within AECs and CTCs showed OATP2B1 is functionally active. Silencing OATP2B1 in CTCs reduced Rosuvastatin propagation from the decidua to the fetal AEC layer within the feto-maternal interface-OOC model. Our data suggest that TPs in FMs may function as a drug transport system at the feto-maternal interface, a function that was previously thought to be performed exclusively by the placenta. This new knowledge will help improve drug delivery testing during pregnancy and contribute to designing drug delivery strategies to treat adverse pregnancy outcomes.

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.

The Impact of Oxidative Stress of Environmental Origin on the Onset of Placental Diseases

Oxidative stress (OS) plays a pivotal role in placental development; however, abnormal loads in oxidative stress molecules may overwhelm the placental defense mechanisms and cause pathological situations. The environment in which the mother evolves triggers an exposure of the placental tissue to chemical, physical, and biological agents of OS, with potential pathological consequences. Here we shortly review the physiological and developmental functions of OS in the placenta, and present a series of environmental pollutants inducing placental oxidative stress, for which some insights regarding the underlying mechanisms have been proposed, leading to a recapitulation of the noxious effects of OS of environmental origin upon the human placenta.

Generation and characterization of human Fetal membrane and Decidual cell lines for reproductive biology experiments†

Human fetal membrane and maternal decidua parietalis form one of the major feto-maternal interfaces during pregnancy. Studies on this feto-maternal interface is limited as several investigators have limited access to the placenta, and experience difficulties to isolate and maintain primary cells. Many cell lines that are currently available do not have the characteristics or properties of their primary cells of origin. Therefore, we created, characterized the immortalized cells from primary isolates from fetal membrane-derived amnion epithelial cells, amnion and chorion mesenchymal cells, chorion trophoblast cells and maternal decidua parietalis cells. Primary cells were isolated from a healthy full-term, not in labor placenta. Primary cells were immortalized using either a HPV16E6E7 retroviral or a SV40T lentiviral system. The immortalized cells were characterized for the morphology, cell type-specific markers, and cell signalling pathway activation. Genomic stability of these cells was tested using RNA seq, karyotyping, and short tandem repeats DNA analysis. Immortalized cells show their characteristic morphology, and express respective epithelial, mesenchymal and decidual markers similar to that of primary cells. Gene expression of immortalized and primary cells were highly correlated (R = 0.798 to R = 0.974). Short tandem repeats DNA analysis showed in the late passage number (>P30) of cell lines matched 84-100% to the early passage number (<P10) of the cell lines revealing there were no genetic drift over the passages. Karyotyping also revealed no chromosomal anomalies. Creation of these cell lines can standardize experimental approaches, eliminate subject to subject variabilities, and benefit the reproductive biological studies on pregnancies by using these cells.

A geroscience motivated approach to treat Alzheimer's disease: Senolytics move to clinical trials

The pathogenic processes driving Alzheimer's disease (AD) are complex. An incomplete understanding of underlying disease mechanisms has presented insurmountable obstacles for developing effective disease-modifying therapies. Advanced chronological age is the greatest risk factor for developing AD. Intervening on biological aging may alter disease progression and represents a novel, complementary approach to current strategies. Toward this end, cellular senescence has emerged as a promising target. This complex stress response harbors damaged cells in a cell cycle arrested, apoptosis-resistant cell state. Senescent cells accumulate with age where they notoriously secrete molecules that contribute to chronic tissue dysfunction and disease. Thus, benefits of cell survival in a senescent fate are countered by their toxic secretome. The removal of senescent cells improves brain structure and function in rodent models at risk of developing AD, and in those with advanced Aβ and tau pathology. The present review describes the path to translating this promising treatment strategy to AD clinical trials. We review evidence for senescent cell accumulation in the human brain, considerations and strategies for senescence-targeting trials specific to AD, approaches to detect senescent brain cells in biofluids, and summarize the goals of the first senolytic trials for the treatment of AD (NCT04063124 and NCT04685590). This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

Cross talk: Trafficking and functional impact of maternal exosomes at the Feto-maternal Interface under normal and pathologic states

Fetal cell-derived exosomes promote inflammation in uterine and cervical cells to promote labor and delivery. However, the effect of maternal exosomes on fetal cells is still not known. We tested the hypothesis that cervical cells exposed to infectious and oxidative stress (OS) signals produce exosomes that can induce inflammation at the feto-maternal interface (FMi). Exosomes isolated from medium samples from human ectocervical epithelial cells (Ecto), endocervical epithelial cells (Endo), and cervical stromal cells (Stroma) in normal cell culture (control) or exposed to infection or OS conditions were characterized based on morphology, size, quantity, expression of tetraspanin markers, and cargo proteins. Human decidual, chorion trophoblast (CTC), chorion mesenchymal (CMC), amnion mesenchymal (AMC), and amnion epithelial cells (AEC) were treated with control, LPS-, or OS-treated cervical exosomes. ELISA for pro-inflammatory cytokines and progesterone was done to determine the recipient cells' inflammatory status. Ecto, endo, and stroma released ∼110 nm, cup-shaped exosomes. LPS and OS treatments did not affect exosome size; however, OS significantly increased the number of exosomes released by all cervical cells. Cervical exosomes were detected by fluorescence microscopy in each target cell after treatment. Exosomes from LPS- and CSE-treated cervical cells increased the inflammatory cytokine levels in the decidual cells, CMC, AMC, and AEC. LPS-treated stromal cell exosomes increased IL-6, IL-8, and progesterone in CTC. In conclusion, infection and OS can produce inflammatory cargo-enriched cervical exosomes that can destabilize FMi cells. However, the refractoriness of CTC to exosome treatments suggests a barrier function of the chorion at the FMi.

The Role and Clinical Interest of Extracellular Vesicles in Pregnancy and Ovarian Cancer

Ovarian cancer and pregnancy are two states in which the host immune system is exposed to novel antigens. Indeed, both the tumor and placenta must invade tissues, remodel vasculature to establish a robust blood supply, and evade detection by the immune system. Interestingly, tumor and placenta tissue use similar mechanisms to induce these necessary changes. One mediator is emerging as a key player in invasion, vascular remodeling, and immune evasion: extracellular vesicles (EVs). Many studies have identified EVs as a key mediator of cell-to-cell communication. Specifically, the cargo carried by EVs, which includes proteins, nucleic acids, and lipids, can interact with cells to induce changes in the target cell ranging from gene expression to migration and metabolism. EVs can promote cell division and tissue invasion, immunosuppression, and angiogenesis which are essential for both cancer and pregnancy. In this review, we examine the role of EVs in ovarian cancer metastasis, chemoresistance, and immune modulation. We then focus on the role of EVs in pregnancy with special attention on the vascular remodeling and regulation of the maternal immune system. Lastly, we discuss the clinical utility of EVs as markers and therapeutics for ovarian cancer and pre-eclampsia.

Role of Extracellular Vesicles in Compromising Cellular Resilience to Environmental Stressors

Extracellular vesicles (EVs), like exosomes, are nanosized membrane-enveloped vesicles containing different bioactive cargo, such as proteins, lipids, mRNA, miRNA, and other small regulatory RNAs. Cell-derived EVs, including EVs originating from stem cells, may capture components from damaged cells or cells impacted by therapeutic treatments. Interestingly, EVs derived from stem cells can be preconditioned to produce and secrete EVs with different therapeutic properties, particularly with respect to heat-shock proteins and other molecular cargo contents. This behavior is consistent with stem cells that also respond differently to various microenvironments. Heat-shock proteins play roles in cellular protection and mediate cellular resistance to radiotherapy, chemotherapy, and heat shock. This review highlights the possible roles EVs play in mediating cellular plasticity and survival when exposed to different physical and chemical stressors, with a special focus on the respiratory distress due to the air pollution.

Extracellular vesicle mediated feto-maternal HMGB1 signaling induces preterm birth

Preterm birth (PTB; <37 weeks of gestation) impacts ∼11% of all pregnancies and contributes to 1 million neonatal deaths worldwide annually. An understanding of the feto-maternal (F-M) signals that initiate birthing (parturition) at term is critical to design strategies to prevent their premature activation, resulting in PTB. Although endocrine and immune cell signaling are well-reported, fetal-derived paracrine signals capable of transitioning quiescent uterus to an active state of labor are poorly studied. Recent reports have suggested that senescence of the fetal amnion membrane coinciding with fetal growth and maturation generates inflammatory signals capable of triggering parturition. This is by increasing the inflammatory load at the feto-maternal interface (FMi) tissues (i.e., amniochorion-decidua). High mobility group box 1 protein (HMGB1), an alarmin, is one of the inflammatory signals released by senescent amnion cells via extracellular vesicles (exosomes; 40-160 nm). Increased levels of HMGB1 in the amniotic fluid, cord and maternal blood are associated with term and PTB. This study tested the hypothesis that senescent amnion cells release HMGB1, which is fetal signaling capable of increasing FMi inflammation, predisposing them to parturition. To test this hypothesis, exosomes from amnion epithelial cells (AECs) grown under normal conditions were engineered to contain HMGB1 by electroporation (eHMGB1). eHMGB1 was characterized (quantity, size, shape, markers and loading efficiency), and its propagation through FMi was tested using a four-chamber microfluidic organ-on-a-chip device (FMi-OOC) that contained four distinct cell types (amnion and chorion mesenchymal, chorion trophoblast and decidual cells) connected through microchannels. eHMGB1 propagated through the fetal cells and matrix to the maternal decidua and increased inflammation (receptor expression [RAGE and TLR4] and cytokines). Furthermore, intra-amniotic injection of eHMGB1 (containing 10 ng) into pregnant CD-1 mice on embryonic day 17 led to PTB. Injecting carboxyfluorescein succinimidyl ester (CFSE)-labeled eHMGB1, we determined in vivo kinetics and report that eHMGB1 trafficking resulting in PTB was associated with increased FMi inflammation. This study determined that fetal exosome mediated paracrine signaling can generate inflammation and induce parturition. Besides, in vivo functional validation of FMi-OOC experiments strengthens the reliability of such devices to test physiologic and pathologic systems.

Microvesicles and exosomes released by amnion epithelial cells under oxidative stress cause inflammatory changes in uterine cells†

Extracellular vesicles play a crucial role in feto-maternal communication and provide an important paracrine signaling mechanism in pregnancy. We hypothesized that fetal cells-derived exosomes and microvesicles (MVs) under oxidative stress (OS) carry unique cargo and traffic through feto-maternal interface, which cause inflammation in uterine cells associated with parturition. Exosomes and MVs, from primary amnion epithelial cell (AEC) culture media under normal or OS-induced conditions, were isolated by optimized differential centrifugation method followed by characterization for size (nanoparticle tracking analyzer), shape (transmission electron microscopy), and protein markers (western blot and immunofluorescence). Cargo and canonical pathways were identified by mass spectroscopy and ingenuity pathway analysis. Myometrial, decidual, and cervical cells were treated with 1 × 107 control/OS-derived exosomes/MVs. Pro-inflammatory cytokines were measured using a Luminex assay. Statistical significance was determined by paired T-test (P < 0.05). AEC produced cup-shaped exosomes of 90-150 nm and circular MVs of 160-400 nm. CD9, heat shock protein 70, and Nanog were detected in exosomes, whereas OCT-4, human leukocyte antigen G, and calnexin were found in MVs. MVs, but not exosomes, were stained for phosphatidylserine. The protein profiles for control versus OS-derived exosomes and MVs were significantly different. Several inflammatory pathways related to OS were upregulated that were distinct between exosomes and MVs. Both OS-derived exosomes and MVs significantly increased pro-inflammatory cytokines (granulocyte-macrophage colony-stimulating factor, interleukin 6 (IL-6), and IL-8) in maternal cells compared with control (P < 0.05). Our findings suggest that fetal-derived exosomes and MVs under OS exhibited distinct characteristics and a synergistic inflammatory role in uterine cells associated with the initiation of parturition.

Osteogenic effects of exosomes derived from human chorion membrane extracts

Objective

Human chorion membrane extracts (CME) are known to exhibit osteogenic effects when used for treating human osteoblast-like cells (MG63 cells), but the active compound in CME remains unknown. The aim of this study was to identify the presence of exosomes in CME and to determine the osteogenic effect of CME exosomes on MG63 cells.

Methods

Exosomes were isolated from human placenta CME using the ExoQuick-TC solution and were characterized. The activity and deposition of alkaline phosphatase (ALP) on MG63 cells cultured with or without exosomes in osteogenic induction medium (OIM) were determined. Human amniotic membrane extracts (AME) were used as controls as they had not affected the osteogenic differentiation of MG63 cells in our previous study.

Results

Transmission electron microscopy (TEM) revealed that exosomes isolated from CME and AME (CME-Exo and AME-Exo, respectively) had a cup-shaped structure. NanoSight™ particle tracking analysis (NTA) confirmed that the size of these exosomes was 100–150 nm. In vitro osteogenic experiments demonstrated that the exosomes from CME, but not those from AME, presented increased alkaline phosphatase (ALP) activity and resulted in the mineralization of MG63 cells in a dose-dependent manner.

Conclusion

Exosomes were identified in CME and AME from the human placenta. Further, the exosomes from CME were found to be capable of promoting osteogenic differentiation, suggesting that exosomes are a key component of CME that stimulate the osteogenesis of human osteoblast-like cells. CME exosomes can be developed as promising therapeutic candidates for bone regeneration.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-021-00218-6.

Pregnancy-Related Extracellular Vesicles Revisited

Extracellular vesicles (EVs) are small vesicles ranging from 20–200 nm to 10 μm in diameter that are discharged and taken in by many different types of cells. Depending on the nature and quantity of their content—which generally includes proteins, lipids as well as microRNAs (miRNAs), messenger-RNA (mRNA), and DNA—these particles can bring about functional modifications in the receiving cells. During pregnancy, placenta and/or fetal-derived EVs have recently been isolated, eliciting interest in discovering their clinical significance. To date, various studies have associated variations in the circulating levels of maternal and fetal EVs and their contents, with complications including gestational diabetes and preeclampsia, ultimately leading to adverse pregnancy outcomes. Furthermore, EVs have also been identified as messengers and important players in viral infections during pregnancy, as well as in various congenital malformations. Their presence can be detected in the maternal blood from the first trimester and their level increases towards term, thus acting as liquid biopsies that give invaluable insight into the status of the feto-placental unit. However, their exact roles in the metabolic and vascular adaptations associated with physiological and pathological pregnancy is still under investigation. Analyzing peer-reviewed journal articles available in online databases, the purpose of this review is to synthesize current knowledge regarding the utility of quantification of pregnancy related EVs in general and placental EVs in particular as non-invasive evidence of placental dysfunction and adverse pregnancy outcomes, and to develop the current understanding of these particles and their applicability in clinical practice.

Exosomes Secreted from Amniotic Membrane Contribute to Its Anti-Fibrotic Activity

Amniotic membranes (AM) have anti-fibrotic activity. Exosomes (nano-sized vesicles) function as conduits for intercellular transfer and contain all the necessary components to induce the resolution of fibrosis. In this study, we tested the hypothesis that the anti-fibrotic activity of AM is mediated by exosomes. AM-derived exosomes or amniotic stromal cell-derived exosomes were isolated and characterized. Anti-fibrotic activity of exosomes was evaluated using human hepatic stellate cells (LX-2), an in vitro model of fibrosis. Exosomes isolated from AM tissue-conditioned media had an average size of 75 nm. Exosomes significantly inhibited the proliferation of TGFβ1-activated LX-2 but had no effect on the proliferation of non-activated LX-2 cells. Exosomes also reduced the migration of LX-2 in a scratch wound assay. Furthermore, exosomes reduced the gene expression of pro-fibrotic markers such as COL1A1, ACTA, and TGFβ1 in LX-2 cells. Interestingly, exosomes isolated from AM tissue under hypoxic conditions seemed to show a stronger anti-fibrotic activity than exosomes isolated from tissue under normoxic conditions. Exosomes released by in vitro cultured AM stromal cells were smaller in size compared with tissue exosomes and also showed anti-fibrotic activity on LX-2 cells. In conclusion, AM-tissue-released exosomes contribute to the anti-fibrotic activity of AM. This is the first report of isolation, characterization, and functional evaluation of exosomes derived from amniotic tissues with the direct comparison between tissue-derived exosomes and cultured cell-derived exosomes.

Extracellular Vesicle Mediated Crosstalk Between the Gametes, Conceptus, and Female Reproductive Tract

Extracellular vesicles (EVs) mediated intracellular communication plays an imperative role in the proper completion of different physiological events. Most of the bio-fluids are enriched with several subpopulations of EVs including exosomes and microvesicles (MVs), with the capacity of transferring different functional molecules (lipids, proteins, and nucleic acids) to target cells. Recipient cells upon receiving the signal molecules undergo different changes that positively affect the structural and functional integrity of the cells. This article was aimed to highlight the role of EVs secreted by gametes, the female reproductive tract, and the growing conceptus in the successful completion of different reproductive events related to gestation. EVs associated with the reproductive system are actively involved in the regulation of different physiological events including gamete maturation, fertilization, and embryo and fetal development. In the reproductive system, EVs mediated intracellular communication is not unidirectional but is rather regulated through crosstalk between the reproductive tract and the growing conceptus. These vesicles are secreted from the ovary, oviductal epithelium, endometrium, developing embryo, and the placenta. The cargo inside these vesicles exerts pleiotropic effects on both maternal and embryonic environments. A better understanding of the EVs-mediated crosstalk will be helpful in the development of useful tools serving both the diagnostic as well as therapeutic needs related to female fertility.

Update review on five top clinical applications of human amniotic membrane in regenerative medicine

Due to the increasing number of studies performed in the field of regenerative medicine during the last two decades, more analytic studies are still needed to clarify the future prospect of this area of science. The main aim of this research was to review the clinical applications of human Amniotic membrane in the field of regenerative medicine critically. Furthermore, in the light of increasing numbers of available products derived from amniotic membrane, we aimed look in depth to see whether regenerative medicine research strategies have a place in the clinical setting. More specifically, in the present study, we attempted to provide insight on developing the new indication for more research and in the next step, for market leaders companies to expand cost-effectiveness of new derived AM products. 20 companies or distributers have offered some commercial products in this field. Survey on more than 90 clinical trials in last five years showed dermatology (and more specific wound healing), orthopedic, and ophthalmology are heavily biased toward multibillion dollar industry. Moreover, urology and dentistry with fewer numbers of clinical data in comparison with the above-mentioned areas, currently are in the path of translation (especially dentistry). In addition, otolaryngology and oncology with the lowest number showed more potential of research thorough understanding the properties that will help guiding the use of AM-derived products in these two areas in future. More than 50% of clinical studies were done or are developing in USA, which have the biggest share in market products. Subsequently, China, Egypt, India, Iran, and Germany with the ongoing clinical trials in different phases may have more approved products in near future.

Sodium Hydrogen Exchanger Regulatory Factor-1 (NHERF1) Regulates Fetal Membrane Inflammation

The fetal inflammatory response, a key contributor of infection-associated preterm birth (PTB), is mediated by nuclear factor kappa B (NF-kB) activation. Na⁺/H⁺ exchanger regulatory factor-1 (NHERF1) is an adapter protein that can regulate intracellular signal transduction and thus influence NF-kB activation. Accordingly, NHERF1 has been reported to enhance proinflammatory cytokine release and amplify inflammation in a NF-kB-dependent fashion in different cell types. The objective of this study was to examine the role of NHERF1 in regulating fetal membrane inflammation during PTB. We evaluated the levels of NHERF1 in human fetal membranes from term labor (TL), term not in labor (TNIL), and PTB and in a CD1 mouse model of PTB induced by lipopolysaccharide (LPS). Additionally, primary cultures of fetal membrane cells were treated with LPS, and NHERF1 expression and cytokine production were evaluated. Gene silencing methods using small interfering RNA targeting NHERF1 were used to determine the functional relevance of NHERF1 in primary cultures. NHERF1 expression was significantly (p < 0.001) higher in TL and PTB membranes compared to TNIL membranes, and this coincided with enhanced (p < 0.01) interleukin (IL)-6 and IL-8 expression levels. LPS-treated animals delivering PTB had increased levels of NHERF1, IL-6, and IL-8 compared to phosphate-buffered saline (PBS; control) animals. Silencing of NHERF1 expression resulted in a significant reduction in NF-kB activation and IL-6 and IL-8 production as well as increased IL-10 production. In conclusion, downregulation of NHERF1 increased anti-inflammatory IL-10, and reducing NHERF1 expression could be a potential therapeutic strategy to reduce the risk of infection/inflammation associated with PTB.

Human Amniotic Epithelial Stem Cells: A Promising Seed Cell for Clinical Applications

Perinatal stem cells have been regarded as an attractive and available cell source for medical research and clinical trials in recent years. Multiple stem cell types have been identified in the human placenta. Recent advances in knowledge on placental stem cells have revealed that human amniotic epithelial stem cells (hAESCs) have obvious advantages and can be used as a novel potential cell source for cellular therapy and clinical application. hAESCs are known to possess stem-cell-like plasticity, immune-privilege, and paracrine properties. In addition, non-tumorigenicity and a lack of ethical concerns are two major advantages compared with embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). All of the characteristics mentioned above and other additional advantages, including easy accessibility and a non-invasive application procedure, make hAESCs a potential ideal cell type for use in both research and regenerative medicine in the near future. This review article summarizes current knowledge on the characteristics, therapeutic potential, clinical advances and future challenges of hAESCs in detail.

Progesterone receptor membrane components: key regulators of fetal membrane integrity

Pro-pregnancy hormone progesterone (P4) helps to maintain a quiescent status of uterine tissues during gestation. However, P4's functional role in maintaining fetal membrane (amniochorion) integrity remains unclear. P4 functions through its membrane receptors (progesterone receptor membrane components (PGRMCs)) as fetal membrane cells lack nuclear receptors. This study screened the differential expression of PGRMCs in the fetal membranes and tested P4-PGRMC interactions under normal and oxidative stress (OS) conditions expected that can disrupt P4-PGRMC interactions impacting fetal membrane stability resulting in parturition. Human fetal membranes were collected from term and preterm deliveries (N = 5). Immunohistochemistry and western blot localized and determined differential expression of P4 receptors. Primary amnion epithelial, mesenchymal (AMCs), and chorion cell were treated with P4 alone or co-treated (P4 + OS induced by cigarette smoke extract (CSE)). Proximity ligation assay (PLA) documented P4-receptor binding, whereas P4 enzyme-linked immunosorbent assay documented culture supernatant levels. Immunohistology confirmed lack of nuclear progesterone receptors; however, confirmed expressions of PGRMC 1 and 2. Term labor (P = 0.01) and preterm rupture (P = 0.01) are associated with significant downregulation of PGRMC2. OS-induced differential downregulation of PGRMCs in both amnion and chorion cells (all P < 0.05) and downregulates P4 release (AMCs; P = 0.01). The PLA showed preferential receptor-ligand binding in amnion and chorion cells. Co-treatment of P4 + CSE did not reverse CSE-induced effects. In conclusion, P4-PGRMCs interaction maintains fetal membranes' functional integrity throughout pregnancy. Increased OS reduces endogenous P4 production and cell type-dependent downregulation of PGRMCs. These changes can lead to fetal membrane-specific "functional progesterone withdrawal," contributing to the dysfunctional fetal membrane status seen at term and preterm conditions.

Extracellular vesicles in spontaneous preterm birth

Feto-maternal communication helps to maintain pregnancy and contributes to parturition at term and preterm. Endocrine and immune factor are well-reported communication mediators. Recent advances in extracellular vesicle (EV) biology have introduced them as major communication channels between the mother and fetus. EVs are round structures with a lipid bilayer membrane. EVs are generally categorized based on their size and mode of biogenesis. The most commonly reported EVs are exosomes with a size range of 30-160 nm that are formed inside the intraluminal vesicles of multivesicular body. Microvesicles (MVs) are larger than > 200 nm and formed by outward budding of plasma membrane. Vesicles are released from all cells and carry various factors that reflect the physiologic state of cell at the time of their release. Analysis of vesicle provides a snapshot of origin cell. Recent studies in perinatal medicine have shown that exosomes are key communicators between feto-maternal units, and they can cross placenta. Fetal-derived exosomes released under term labor-associated conditions can cause parturition-associated changes in maternal uterine tissues. Exosomes carrying inflammatory cargo can cause preterm birth in animal models suggesting their functional role in parturition. A few reports have profiled differences between exosome cargos from term and preterm pregnancies and indicated their biomarker potential to predict high-risk pregnancy status. There are hardly any reports on MVs and their functional roles in reproduction. Herein, we review of EVs and MVs, their characteristics, function, and usefulness predicting adverse pregnancy complications such as preterm birth.

Contractile function of the cervix plays a role in normal and pathological pregnancy and parturition

The cervix plays an integral part in ensuring the proper timing of pregnancy and parturition. It maintains the fetus within the uterus and protects it from pathogens present in the vaginal canal. The cervix undergoes extensive remodeling during pregnancy and parturition. This process is associated with collagen degradation, an increase in immune cell response and inflammation in the cervix. However, our understanding of the role of cervical smooth muscles and their contribution to cervical remodeling is still lacking. In this paper, we propose that the active contractile function of the cervix influences cervical remodeling during pregnancy and parturition. Contraction of the cervical smooth muscles helps the cervix to remain firm and closed during early pregnancy, while relaxation of the cervical smooth muscles help facilitate cervical dilatation during labor. This contractile function of the cervix can be influenced by endocrine signals, such as estrogen, progesterone, and oxytocin; local paracrine signals, such as inflammatory chemokines and cytokines, as well as extracellular vesicles, such as exosomes and ectosomes; and by pharmacological agents used for cervical ripening and the induction of labor. A deeper understanding of the role of smooth muscles in cervical remodeling can help us elucidate the cellular processes in the cervix during pregnancy and parturition. This can also help in finding critical signaling pathways and therapeutic targets in the cervix that may decrease the rates of premature cervical ripening and preterm birth.

Oxidative stress-induced downregulation of glycogen synthase kinase 3 beta in fetal membranes promotes cellular senescence†

OBJECTIVE

Oxidative stress (OS)-induced stress signaler p38 mitogen-activated protein kinase (p38MAPK) activation and fetal membrane senescence are associated with parturition. This study determined changes in glycogen synthase kinase 3 beta (GSK3β) and its regulation by p38MAPK in effecting senescence to further delineate the molecular mechanism involved in senescence.

METHODS

Primary human amnion epithelial cells and amnion mesenchymal cells were treated with cigarette smoke extract (CSE, OS inducer). Expression of total and phosphorylated GSK3β and p38MAPK, and that of GSK3β's downstream targets: beta-catenin (β-Cat) and nuclear factor erythroid 2-related factor 2 (Nrf2) (western blot analysis), cell cycle regulation and senescence (flow cytometry) were determined. The specificity of GSK3β and p38MAPK's mechanistic role was tested by co-treating cells with their respective inhibitors, CHIR99021 and SB203580. Exosomal secretion of β-Cat from OS-induced cells was confirmed by immunofluorescence confocal microscopy and western blot.

RESULTS

OS induced by CSE resulted in phosphorylation of GSK3β (inactivation) and p38MAPK (activation) that was associated with cell cycle arrest and senescence. Inhibitors to GSK3β and p38MAPK verified their roles. Glycogen synthase kinase 3 beta inactivation was associated with nuclear translocation of antioxidant Nrf2 and exosomal secretion of β-Cat.

CONCLUSIONS

OS-induced P-p38MAPK activation is associated with functional downregulation of GSK3β and arrest of cell cycle progression and senescence of amnion cells. Lack of nuclear translocation of β-Cat and its excretion via exosomes further supports the postulation that GSK3β down-regulation by p38MAPK may stop cell proliferation preceding cell senescence. A better understanding of molecular mechanisms of senescence will help develop therapeutic strategies to prevent preterm birth.

Isolation and characterization human chorion membrane trophoblast and mesenchymal cells

INTRODUCTION

To develop protocols for isolation and culture of human chorionic mesenchymal and trophoblast cells and test their differential responsiveness to oxidative stress.

METHODS

Chorion trophoblast cells (CTC) and chorion mesenchymal cells (CMC) were isolated from term fetal membranes by modifying current protocols. Their purity and characteristics were tested using bright field microscopy and after staining for cytokeratin (CK)-7 and vimentin. Cigarette smoke extract (CSE) was used to stimulate cells, and we determined reactive oxygen species (ROS) production using 2'7'-dichlorodihydro-fluorescein assay, stress signaler p38MAPK activation (Western blot) and senescence by flow cytometry. Co-treatment with antioxidant N-acetyl cystine (NAC) either alone or in combination with SB203580 (p38MAPK inhibitor) was used to test oxidative stress (OS)- and p38MAPK-mediated effects.

RESULTS

The isolation and cell culture protocol used in this study yielded 92% pure CTC and 100% pure CMC. CSE treatment significantly induced ROS production, P-p38MAPK activation, and senescence in both cell types compared to controls. Cotreatment with NAC reduced ROS production and p38MAPK activation, and co-treatment with both NAC and SB203580 reduced senescence. ROS response in CMC was higher than CTC; however, senescence of CTC was 10-fold higher than CMC.

CONCLUSIONS

We introduce approaches for proper isolation and culture of CTC and CMC without any influence or overgrowth of one specific type cell that can confound results. Using this approach, we determined differential effects of CTC and CMC to OS condition seen at term labor. Both CTC and CMC undergo p38MAPK-mediated senescence; however, the rate of senescence is higher in CTC.

Dexamethasone induces primary amnion epithelial cell senescence through telomere-P21 associated pathway†

Dexamethasone (Dex), a corticosteroid hormone, is used during the perinatal period to help fetal lung and other organ development. Conversely, Dex-induced cell proliferation has been associated with accelerated aging. Using primary amnion epithelial cells (AECs) from term, not in labor, fetal membranes, we tested the effects of Dex on cell proliferation, senescence, and inflammation. Primary AECs treated with Dex (100 and 200 nM) for 48 h were tested for cell viability (crystal violet dye exclusion), cell cycle progression and/or type of cell death (flow cytometry), expression patterns of steroid receptors (glucocorticoid receptor, progesterone receptor membrane component 1&2), inflammatory mediators (IL-6 and IL-8), and telomere length (quantitative RT-PCR). Mechanistic mediators of senescence (p38MAPK and p21) were determined by western blot analysis. Dex treatment did not induce AEC proliferation, cell cycle, influence viability, or morphology. However, Dex caused dependent telomere length reduction and p38MAPK-independent but p21-dependent (confirmed by treatment with p21 inhibitor UC2288). Senescence was not associated with an increase in inflammatory mediators, which is often associated with senescence. Co-treatment with RU486 produced DNA damage, cell cycle arrest, and cellular necrosis with an increase in inflammatory mediators. The effect of Dex was devoid of changes to steroid receptors, whereas RU486 increased GR expression. Dex treatment of AECs produced nonreplicative and noninflammatory senescence. Extensive use of Dex during the perinatal period may lead to cellular senescence, contributing to cellular aging associated pathologies during the perinatal and neonatal periods.