Laboratory models for studying ectopic pregnancy

Transuterine relocation of pregnant uterine horn segment in an exploratory rat model with implications for tubal ectopic pregnancy

Ectopic pregnancy affects ~ 2% of pregnancies annually in the United States, with no current treatments allowing for the continuation of the pregnancy. Thus, this study sought to initiate an investigation into the potential design of a surgical technique, in an animal model, that could serve as a foundation for future research into the potential of relocating an ectopic embryo into the uterus at the human level. Female Long-Evans rats were randomly assigned to one of two groups: Embryo Relocation (ER; n = 12; underwent embryo relocation surgery) and Normal Pregnancy (NP; n = 12; carried a normal pregnancy; no surgery). Eight rats/group were allowed to carry their pregnancy to term and deliver, while four had their uteri collected at the end of gestation. Briefly, for the ER group, a uterine horn containing 1-2 embryos was translocated to the contralateral horn, which had been incised and cleared of its contents, prior to being wrapped around the relocated horn. Rat weight, food consumption and vaginal impedance of the mothers were measured throughout the experiment. Ultrasounds were performed and fetal heart rates measured on day 20-21 of gestation. Additionally, rat weight of all offspring was measured at adulthood. Our findings indicate that, in the ER group, 15/15 (100%) of the relocated embryos had detectable heart rates at the end of gestation (within the normal range), 14/15 (93%) were delivered vaginally, and 12/14 (86%) survived until adulthood. A significant decrease in rat weight and food consumption was observed only on the day following surgery. Fertility, as measured by vaginal impedance, was minimally impacted by surgery. Moreover, there was no significant difference between groups in average body weight of offspring at adulthood. Histological analysis indicated a thicker placenta in the ER group, attributable to the fetal part of the placenta, potentially indicating compensatory mechanisms. Our findings reflect a successful transuterine embryo relocation followed by vaginal birth and survival of offspring to adulthood, in a rat model. Such findings lay the foundation for future preclinical research in higher animals, with potential implications on a procedure relevant to human ectopic embryo relocation.

Glutathione-Responsive Methotrexate Polymersomes for Potential Management of Ectopic Pregnancy

The first-line treatment for ectopic pregnancy (EP), the chemotherapeutic methotrexate (MTX), has a failure rate of more than 10%, which can lead to severe complications or death. Inadequate accumulation of administered MTX at the ectopic implantation site significantly contributes to therapeutic failure. This study reports the first glutathione-responsive polymersomes for efficient delivery of MTX to the implantation site and its triggered release in placental cells. Fluorescence and photoacoustic imaging have confirmed that the developed polymersomes preferentially accumulate after systemic administration in the implantation site of pregnant mice at early gestational stages. The high concentrations of intracellular glutathione (GSH) reduce an incorporated disulfide bond within polymersomes upon internalization into placental cells, resulting in their disintegration and efficient drug release. Consequently, MTX delivered by polymersomes induces pregnancy demise in mice, as opposed to free MTX at the same dose regimen. To achieve the same therapeutic efficacy with free MTX, a sixfold increase in dosage is required. In addition, mice successfully conceive and birth healthy pups following a prior complete pregnancy demise induced by methotrexate polymersomes. Therefore, the developed MTX nanomedicine can potentially improve EP management and reduce associated mortality rates and related cost.

Classical Estrogen Signaling in Ciliated Epithelial Cells of the Oviduct Is Nonessential for Fertility in Female Mice

Ciliary action performs a critical role in the oviduct (Fallopian tube) during pregnancy establishment through sperm and egg transport. The disruption of normal ciliary function in the oviduct affects oocyte pick-up and is a contributing factor to female infertility. Estrogen is an important regulator of ciliary action in the oviduct and promotes ciliogenesis in several species. Global loss of estrogen receptor α (ESR1) leads to infertility. We have previously shown that ESR1 in the oviductal epithelial cell layer is required for female fertility. Here, we assessed the role of estrogen on transcriptional regulation of ciliated epithelial cells of the oviduct using single-cell RNA-sequencing analysis. We observed minor variations in ciliated cell genes in the proximal region (isthmus and uterotubal junction) of the oviduct. However, 17β-estradiol treatment had little impact on the gene expression profile of ciliated epithelial cells. We also conditionally ablated Esr1 from ciliated epithelial cells of the oviduct (called ciliated Esr1d/d mice). Our studies showed that ciliated Esr1d/d females had fertility rates comparable to control females, did not display any disruptions in preimplantation embryo development or embryo transport to the uterus, and had comparable cilia formation to control females. However, we observed some incomplete deletion of Esr1 in the ciliated epithelial cells, especially in the ampulla region. Nevertheless, our data suggest that ESR1 expression in ciliated cells of the oviduct is dispensable for ciliogenesis and nonessential for female fertility in mice.

Virtual segmentation of three-dimensional ultrasound images of morphological structures of an ex vivo ectopic pregnancy inside a fallopian tube

Ex vivo ultrasound (US) of human tissues has been used for decades on the study of the acoustic physical aspects of the US, to the study of the morphology of the organs. Using three-dimensional (3D) US, we demonstrate the possibilities to study surgical specimens from gynecological conditions. 3D images of the surgical specimen were collected and virtually segmented according to the contrast of its images, providing a 3D image of the ectopic pregnancy and its effects on the fallopian tube.

Effect and Role of miR-196b in Ectopic Pregnancy

Ectopic pregnancy (EP) is associated with significant morbidity and mortality, but the molecular mechanism of this condition is still unclear. miR-196b, a hot research direction for the past few years, participates in the occurrence of various diseases but whether it plays a regulatory role in EP is still unclear. This research was set to investigate the expression and potential value of miR-196b in EP. qRT-PCR was utilized to determine the relative expression of miR-196b in peripheral blood of EP patients and to observe the expression changes of miR-196b before and after treatment. Correlation analysis of miR-196b with HCG and progesterone was performed. Logistic regression analysis was applied to independent risk factors affecting EP patients. TargetScan was utilized to predict the downstream target genes of miR-196b, and GO and KEGG analysis was carried out using the R language pack. qRT-PCR showed that miR-196b expression in peripheral blood of EP patients was lower than that of normal people. miR-196b expression in patients after treatment was notably higher than that before treatment. In addition, correlation analysis showed that miR-196b was positively correlated with the expression of HCG, progesterone, and estradiol. Risk factor analysis revealed that abortion history, pelvic inflammatory disease history, lower abdominal surgery history, and miR-196b were independent risk factors for EP, and the AUC of the combined ROC curve was 0.899. GO function enrichment and KEGG signal pathway enrichment found 10 potential functions and 2 potential signal pathways of miR-196b. miR-196b is expressed in EP patients, is differentially expressed according to the change in EP condition, and is expected to become a promising index for clinical diagnosis of EP.

Pelvic Chlamydial Infection Predisposes to Ectopic Pregnancy by Upregulating Integrin β1 to Promote Embryo-tubal Attachment

Tubal ectopic pregnancies are a leading cause of global maternal morbidity and mortality. Previous infection with Chlamydia trachomatis is a major risk factor for tubal embryo implantation but the biological mechanism behind this association is unclear. Successful intra-uterine embryo implantation is associated with increased expression of endometrial "receptivity" integrins (cell adhesion molecules). We examined integrin expression in Fallopian tubes of women with previous C. trachomatis infection, in mice experimentally infected with C. trachomatis, in immortalised human oviductal epithelial cells (OE-E6/E7) and in an in vitro model of human embryo attachment (trophoblast spheroid-OE-E6/7 cell co-culture). Previous exposure with C. trachomatis increased Fallopian tube/oviduct integrin-subunit beta-1 (ITGB1) in women and mice compared to controls. C. trachomatis increased OE-E6/E7 cell ITGB1 expression and promoted trophoblast attachment to OE-E6/E7 cells which was negated by anti-ITGB1-antibody. We demonstrate that infection with C. trachomatis increases tubal ITGB1 expression, predisposing to tubal embryo attachment and ectopic pregnancy.

mRNA expression of VEGF and its receptors in fallopian tubes of women with ectopic pregnancies

BACKGROUND

Establishment of viable pregnancy requires embryo implantation and placentation. Ectopic pregnancy (EP) is a pregnancy complication which occurs when an embryo implants outside of the uterine cavity, most often in a fallopian tube. On the other hand, an important aspect of successful implantation is angiogenesis. Vascular endothelial growth factor (VEGF) is a potent angiogenic factor responsible for vascular development that acts through its receptors, VEGF receptor 1 (VEGFR1) and VEGFR2. This study aims to investigate mRNA expression of VEGF and its receptors in fallopian tubes of women who have EP compared with fallopian tubes of pseudo-pregnant women. We hypothesize that expression of VEGF and its receptors in human fallopian tubes may change during EP.

MATERIALS AND METHODS

This was a case-control study. The case group consisted of women who underwent salpingectomy because of EP. The control group consisted of women with normal fallopian tubes that underwent hysterectomy. Prior to tubal sampling, each control subject received an injection of human chorionic gonadotropin (hCG) to produce a state of pseudo-pregnancy. Fallopian tubes from both groups were procured. We investigated VEGF, VEGFR1 and VEGFR2 mRNA expressions in different sections of these tubes (infundibulum, ampulla and isthmus) by reverse transcription polymerase chain reaction (RT-PCR) and quantitative PCR (Q-PCR).

RESULTS

RT-PCR showed expressions of these genes in all sections of the fallopian tubes in both groups. Q-PCR analysis revealed that expressions of VEGF, VEGFR1 and VEGFR2 were lower in all sections of the fallopian tubes from the case group compared to the controls. Only VEGFR2 had higher expression in the ampulla of the case group.

CONCLUSION

Decreased expressions of VEGF, VEGFR1 and VEGFR2 in the EP group may have a role in the pathogenesis of embryo implantation in fallopian tubes.

Embryonic miRNA profiles of normal and ectopic pregnancies

Our objective was to investigate the miRNA profile of embryonic tissues in ectopic pregnancies (EPs) and controlled abortions (voluntary termination of pregnancy; VTOP). Twenty-three patients suffering from tubal EP and twenty-nine patients with a normal ongoing pregnancy scheduled for a VTOP were recruited. Embryonic tissue samples were analyzed by miRNA microarray and further validated by real time PCR. Microarray studies showed that four miRNAs were differentially downregulated (hsa-mir-196b, hsa-mir-30a, hsa-mir-873, and hsa-mir-337-3p) and three upregulated (hsa-mir-1288, hsa-mir-451, and hsa-mir-223) in EP compared to control tissue samples. Hsa-miR-196, hsa-miR-223, and hsa-miR-451 were further validated by real time PCR in a wider population of EP and control samples. We also performed a computational analysis to identify the gene targets and pathways which might be modulated by these three differentially expressed miRNAs. The most significant pathways found were the mucin type O-glycan biosynthesis and the ECM-receptor-interaction pathways. We also checked that the dysregulation of these three miRNAs was able to alter the expression of the gene targets in the embryonic tissues included in these pathways such as GALNT13 and ITGA2 genes. In conclusion, analysis of miRNAs in ectopic and eutopic embryonic tissues shows different expression patterns that could modify pathways which are critical for correct implantation, providing new insights into the understanding of ectopic implantation in humans.

Association between increased expression of endothelial isoform of nitric oxide synthase in the human fallopian tube and tubal ectopic pregnancy

BACKGROUND

Tubal ectopic pregnancy (tEP) is the most common type of extra-uterine pregnancy and the most common cause of maternal mortality. Nitric oxide (NO) is a molecule that incorporates in many physiological processes of female reproductive system. Recent studies have demonstrated the possible role of endothelial isoform of nitric oxide synthase (eNOS) enzyme in the regulation of many reproductive events that occur in the fallopian tube (FT).

OBJECTIVE

The aim of this study was to evaluate the expression of eNOS in the FTs of women with tEP.

MATERIALS AND METHODS

In this case-control study, a total number of 30FTs samples were obtained from three groups including: 10 FTs of women that bearing an EP, 10 FTs from the non-pregnant women at luteal phase of the menstrual cycle, and 10 FTs of healthy pregnant women (n=10). Samples were fixed in 10% buffered formalin and then were evaluated by immunohistochemistry.

RESULTS

Localization of eNOS was seen in secretory and ciliated luminal epithelium and vascular endothelium of all groups. However, we did not observed the expression of eNOS in smooth muscle cells of all groups. Expression of eNOS in luminal epithelium of women with EP compared to non-pregnant women at luteal phase of menstrual cycle and healthy pregnant group showed statistically significant increase (p=0.00). Significant difference in expression of eNOS was not observed in luminal epithelium of FTs of women at luteal phase compared to healthy pregnant groups (p=0.78).

CONCLUSION

This study indicates that changes in expression of eNOS in luminal epithelium of FT may lead to development of EP. This article extracted from M.Sc. thesis. (Leyla Fath Bayati).

Biomarkers for ectopic pregnancy and pregnancy of unknown location

Early pregnancy failure is the most common complication of pregnancy, and 1% to 2% of all pregnancies will be ectopic. As one of the leading causes of maternal morbidity and mortality, diagnosing ectopic pregnancy and determining the fate of a pregnancy of unknown location are of great clinical concern. Several serum and plasma biomarkers for ectopic pregnancy have been investigated independently and in combination. The following is a review of the state of biomarker discovery and development for ectopic pregnancy and pregnancy of unknown location.

The paracrinology of tubal ectopic pregnancy

As part of successful human reproduction, the Fallopian tube must provide a suitable environment for pre-implantation development of the embryo and for efficient transport of the embryo to the uterus for implantation. These functions are coordinated by paracrine interactions between tubal epithelial, smooth muscle and immune cells and the cells of the developing embryo. Alterations in these signals can lead to a tubal microenvironment encouraging of embryo implantation and to dysregulated tubal motility, ultimately resulting in inappropriate and early implantation of the embryo in the Fallopian tube. Here, we highlight novel and emerging concepts in tubal physiology and pathobiology, such as the induction of a receptive phenotype within the Fallopian tube, leading to ectopic implantation. Chlamydia trachomatis infection is a risk factor for tubal ectopic pregnancy. Activation of toll-like receptor 2 (TLR-2) in the Fallopian tube epithelium, by C. trachomatis has recently been demonstrated, leading to the dysregulation of factors involved in implantation and smooth muscle contractility, such as prokineticins (PROK), activin A and interleukin 1 (IL-1). The Fallopian tube has also recently been shown to harbour a unique population of immune cells, compared to the endometrium. In addition, the complement of immune cells in the Fallopian tube has been reported to be altered in Fallopian tube from women with ectopic pregnancy. There are increasing data suggesting that vascularisation of the Fallopian tube, by the embryo during ectopic pregnancy, differs from that initiated in the uterus during normal pregnancy. This too, is likely the result of paracrine signals between the embryo and the tubal microenvironment.

Possible role of adrenomedullin in the pathogenesis of tubal ectopic pregnancy

CONTEXT

Tubal ectopic pregnancy (tEP) is currently the leading cause of pregnancy-related deaths during the first trimester. Our current knowledge on the molecular pathogenesis is limited.

OBJECTIVE

The objective of the study was to find out the possible role of adrenomedullin (ADM) in the pathogenesis of tEP.

DESIGN

This was an experimental in vitro study on oviductal tissue.

SETTING

The study was conducted at a university teaching hospital.

PATIENTS AND INTERVENTIONS

Patients included those having oviducts removed surgically during salpingectomy for tEP or hysterectomy for benign gynecological conditions. Oviductal tissues were incubated in hormonal condition mimicking early pregnancy before used for in vitro experiments.

MAIN OUTCOME MEASURES

Plasma ADM concentration, oviductal expression of ADM and its receptors, ciliary beat frequency, smooth muscle contraction were measured.

RESULTS

The ciliary beat frequency and frequency of muscle contraction were lower in the oviducts from patients with tEP than those from simulated normal pregnancy. The plasma and oviductal tissue ADM levels were also lower. The decreases in ciliary beat and frequency of contraction were restored to normal after ADM treatment.

CONCLUSIONS

The results suggest that the lower ADM level in the oviducts of tEP may lead to the decrease in ciliary beating and muscle contraction, with the result that the embryo is retained and implanted in the oviduct. Our findings explain for the first time the etiology of tubal pregnancy on the basis of an impairment of the transport of the fertilized ovum resulting from an ADM deficiency and raise the possibility of using the plasma ADM level as a predictor for tubal ectopic pregnancy.

Mechanisms of disease: the endocrinology of ectopic pregnancy

Ectopic pregnancy is defined as a pregnancy implanted outside the uterus, and >98% implant in the Fallopian tube. It has a major clinical and socioeconomic impact worldwide. The diagnosis of ectopic pregnancy is often difficult and resource intensive owing to a lack of accurate biomarkers, and there is a need for improved medical management of ectopic pregnancy using new or adjuvant treatments. The aetiology of ectopic pregnancy is uncertain, but tubal implantation is probably due to retention of the embryo in the Fallopian tube owing to impaired embryo-tubal transport and alterations in the tubal microenvironment. This comprehensive review of the literature supporting current understanding of the endocrinology of Fallopian tube biology and tubal implantation focuses on genes expressed in the Fallopian tube regulated by oestrogen and progesterone and discusses their potential functions. It concludes with a discussion of how advances in this field are enabling the development of novel biomarkers and could lead to the identification of potential new treatments for ectopic pregnancy.

Human fallopian tube epithelium constitutively expresses integrin endometrial receptivity markers: no evidence for a tubal implantation window

Understanding of ectopic implantation within the Fallopian tube (FT) is limited. In the human uterus, the putative 'window of implantation' in the mid-luteal phase of the menstrual cycle is accompanied by increased endometrial epithelial expression of the integrins α(1)β(1), α(4)β(1) and α(v)β(3) and its ligand osteopontin. Similar cyclical changes in FT integrin expression have been proposed to contribute to ectopic implantation, but supporting data are limited. In the current study, we present quantitative data on human FT transcription and translation of the integrin subunits α(1), α(4), α(V), β(1) and β(3) during the follicular and mid-luteal phases of the menstrual cycle, together with a supporting immuocytochemical analysis of their spatial distribution within the FT, and that of osteopontin. In contrast to previous studies, our data indicate that all five integrin receptivity markers are constitutively transcribed and translated in the FT, with no evidence for changes in their expression or distribution during the window of implantation in the mid-luteal phase of the cycle. Furthermore, we could find no evidence for cyclic redistribution of the integrin α(v)β(3) ligand osteopontin within the FT. Although we do not rule out the involvement of integrin endometrial receptivity markers in the establishment of ectopic pregnancy, our findings do not support their differential expression during a tubal implantation window.