Coculturing human endometrial epithelial cells and stromal fibroblasts alters cell-specific gene expression and cytokine production

How telomere maintenance affects endometriosis development: a preliminary study

Background: Endometriosis results in dysmenorrhea, dyspareunia, chronic pelvic pain and infertility in reproductive-age women. However, no effective treatment methods have been applied to the disease, and the pathogenesis of endometriosis is unclear. Purpose: This study was performed to investigate the association between telomere maintenance and endometriosis development. Materials and methods: The telomere length of the postmenopausal endometria, eutopic endometria and their matched ectopic lesions in the proliferative and secretory phases was detected using fluorescence in situ hybridization (FISH) methods, and the effect of telomere length maintenance on the proliferation of endometrial cells derived from endometriotic patients was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay with BIBR1532 treatment. Then all of the telomere maintenance genes were extracted from the Telnet database, and bioinformatics analysis was performed to uncover the role of telomere maintenance genes in endometriosis development. Results: Telomere length was longer in endometriotic patients' eutopic endometria during the proliferative and secretory phases, and treatment with a telomerase inhibitor inhibited the proliferation of epithelial cells and stromal cells. Furthermore, the telomere maintenance genes were enriched in several hormone-related pathways, with several genes differentially expressed between normal endometria and endometria derived from endometriotic patients. The nomogram constructed based on telomere maintenance genes also displayed good predictive value. Conclusions: Telomere maintenance may contribute to the development of endometriosis, with several related genes involved.

Modelling Endometriosis Using In Vitro and In Vivo Systems

Endometriosis is a chronic inflammatory condition characterised by the presence of endometrium-like tissue outside the uterus. Despite its high prevalence and recent advances in molecular science, many aspects of endometriosis and its pathophysiology are still poorly understood. Previously, in vitro and in vivo modelling have been instrumental in establishing our current understanding of endometriosis. As the field of molecular science and the advance towards personalised medicine is ever increasing, more sophisticated models are continually being developed. These hold great potential to provide more intricate knowledge of the underlying pathophysiology and facilitate investigations into potential future approaches to diagnosis and treatment. This review provides an overview of different in vitro and in vivo models of endometriosis that are pertinent to establishing our current understanding. Moreover, we discuss new cross-cutting approaches to endometriosis modelling, such as the use of microfluidic cultures and 3D printing, which have the potential to shape the future of endometriosis research.

Epidemiologically relevant phthalates affect human endometrial cells in vitro through cell specific gene expression changes related to the cytoskeleton and mitochondria

Phthalates are endocrine disrupting chemicals (EDCs) found in common consumer products such as soft plastics and cosmetics. Although the knowledge regarding the adverse effects of phthalates on female fertility are accumulating, information on the hormone sensitive endometrium is still scarce. Here, we studied the effects of phthalates on endometrial cell proliferation and gene expression. Human endometrial primary epithelial and stromal cells were isolated from healthy fertile-aged women (n=3), and were compared to endometrial cell lines T-HESC and Ishikawa. Three different epidemiologically relevant phthalate mixtures were used, defined by urine samples in the Midlife Women Health Study (MWHS) cohort. Mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was used as a single phthalate control. Cells were harvested for proliferation testing and transcriptomic analyses after 24 h exposure. Even though all cell models responded differently to the phthalate exposures, many overlapping differentially expressed genes (DEGs, FDR<0.1), related to cell adhesion, cytoskeleton and mitochondria were found in all cell types. The qPCR analysis confirmed that MEHHP significantly affected cell adhesion gene vinculin (VCL) and NADH:ubiquinone oxidoreductase subunit B7 (NDUFB7), important for oxidative phosphorylation. Benchmark dose modelling showed that MEHHP had significant concentration-dependent effects on cytoskeleton gene actin-beta (ACTB). In conclusion, short 24 h phthalate exposures significantly altered gene expression cell-specifically in human endometrial cells, with six shared DEGs. The mixture effects were similar to those of MEHHP, suggesting MEHHP could be the main driver in the mixture. Impact of phthalate exposures on endometrial functions including receptivity should be addressed.

Oviduct and endometrial epithelium improve in vitro produced bovine embryo developmental kinetics

In brief

Standard in vitro produced (IVP) bovine embryo culture media limit embryonic development. Culturing IVP bovine embryos in standard IVP bovine embryo culture media conditioned with oviduct and/or endometrial cells improves blastocyst formation and reduces the time to formation.

Abstract

In vitro embryo production in cattle greatly impacts blastomere biochemistry, embryo rate of development and pre- and post-transfer survival. In vivo, the bovine embryo migrates through the oviduct isthmus before entering the uterus on approximately day 4 of development where it remains unattached within the uterine lumen until day 20 of gestation. During this time, the embryo is sequentially exposed to oviduct followed by endometrial secretions that support embryonic development. Considering this, we tested the effect of culturing in vitro produced (IVP) bovine embryos sequentially in oviduct epithelial- (OEp; days 1-3) followed by endometrial epithelial- (EEp) or EEp and fibroblast cell (EEp/F; days 4-8)-conditioned media on embryonic development using a time-lapse monitoring system. Compared to control, culturing IVP embryos in EEp- or EEp/F-conditioned media without prior culture in OEp-conditioned media increased blastocyst formation (P < 0.05) and reduced the time to blastocyst formation (P < 0.05). Culturing IVP bovine embryos in OEp-conditioned media followed by EEp- or EEp/F-conditioned media, however, had the greatest impact on embryo developmental kinetics and increased morula and blastocyst formation (P < 0.05) and reduced time to formation (P < 0.05). Day 8 blastocyst cell numbers, diameter and quality were not significantly different, although, blastocyst quality scores were less (indicative of better quality) for all cell-conditioned media compared to control. In conclusion, IVP bovine embryo development may be improved using a sequential embryo culture system involving bovine oviduct followed by endometrial cell-conditioned media.

BIBR1532 Affects Endometrial Cell Proliferation, Migration, and Invasion in Endometriosis via Telomerase Inhibition and MAPK Signaling

OBJECTIVES

The effect of telomerase inhibitor BIBR1532 on endometriotic cells was investigated to explore the inhibitory effect of targeting telomerase on endometriosis.

DESIGN

In vitro primary cell culture study. Participants/Materials: Primary endometrial cells derived from eutopic and ectopic endometrium in patients with endometriosis.

SETTING

The study was conducted in the university hospital.

METHODS

Paired eutopic and ectopic endometrial cells were collected from 6 patients from January 2018 to July 2021. A TRAP assay was performed to detect the telomerase activity of the cells. MTT, cell cycle, apoptosis, migration, and invasion assays were performed to study the inhibitory effect of BIBR1532. Enrichment analysis was performed to identify the key pathways involved in endometriosis progression and telomerase action. Then, Western blotting was used to investigate the expression of related proteins.

RESULTS

BIBR1532 treatment significantly inhibited the growth of eutopic and ectopic endometrial cells, with apoptosis and cell cycle signaling involved. Migration and invasion, important characteristics for the establishment of ectopic lesions, were also inhibited by BIBR1532. The MAPK signaling cascade, related to telomerase and endometriosis, was decreased in eutopic and ectopic endometrial stromal cells with the treatment of BIBR1532.

LIMITATIONS

The severe side effects of telomerase inhibitors might be the main obstacle to clinical application, so it is necessary to find better drug delivery methods in vivo.

CONCLUSIONS

The telomerase inhibitor BIBR1532 affects endometrial cell proliferation, migration, and invasion in endometriosis.

Basolateral secretions of human endometrial epithelial organoids impact stromal cell decidualization

Uterine glands and, by inference, their secretions impact uterine receptivity, blastocyst implantation, stromal cell decidualization, and placental development. Changes in gland function across the menstrual cycle are primarily governed by the steroid hormones estrogen (E2) and progesterone (P4) but can also be influenced by extrinsic factors from the stroma. Using a human endometrial epithelial organoid system, transcriptome and proteome analyses identified distinct responses of the organoids to steroid hormones and prostaglandin E2 (PGE2). Notably, P4 and PGE2 modulated the basolateral secretion of organoid proteins, particularly cystatin C (CST3), serpin family A member 3 (SERPINA3), and stanniocalcin 1 (STC1). CST3, but not SERPINA3 or STC1, attenuated the in vitro stromal decidualization response to steroid hormones and PGE2. These findings provide evidence that uterine gland-derived factors impact stromal cell decidualization, which has implications for pregnancy establishment and fertility in women.

MSX1 Regulates Goat Endometrial Function by Altering the Plasma Membrane Transformation of Endometrial Epithelium Cells during Early Pregnancy

MSX1 is an important member of the muscle segment homeobox gene (Msh) family and acts as a transcription factor to regulate tissue plasticity, yet its role in goat endometrium remodeling remains elusive. In this study, an immunohistochemical analysis showed that MSX1 was mainly expressed in the luminal and glandular epithelium of goat uterus, and the MSX1 expression was upregulated in pregnancy at days 15 and 18 compared with pregnancy at day 5. In order to explore its function, goat endometrial epithelial cells (gEECs) were treated with 17 β-estrogen (E₂), progesterone (P₄), and/or interferon-tau (IFNτ), which were used to mimic the physiological environment of early pregnancy. The results showed that MSX1 was significantly upregulated with E₂- and P₄-alone treatment, or their combined treatment, and IFNτ further enhanced its expression. The spheroid attachment and PGE2/PGF2α ratio were downregulated by the suppression of MSX1. The combination of E₂, P₄, and IFNτ treatment induced the plasma membrane transformation (PMT) of gEECs, which mainly showed the upregulation of N-cadherin (CDH2) and concomitant downregulation of the polarity-related genes (ZO-1, α-PKC, Par3, Lgl2, and SCRIB). The knockdown of MSX1 partly hindered the PMT induced by E₂, P₄, and IFNτ treatment, while the upregulation of CDH2 and the downregulation of the partly polarity-related genes were significantly enhanced when MSX1 was overexpressed. Moreover, MSX1 regulated the CDH2 expression by activating the endoplasmic reticulum (ER) stress-mediated unfolded protein response (UPR) pathway. Collectively, these results suggest that MSX1 was involved in the PMT of the gEECs through the ER stress-mediated UPR pathway, which affects endometrial adhesion and secretion function.

Endometrial Stem/Progenitor Cells–Their Role in Endometrial Repair and Regeneration

The human endometrium is a remarkable tissue, undergoing ~450 cycles of proliferation, differentiation, shedding (menstruation), repair, and regeneration over a woman's reproductive lifespan. Post-menstrual repair is an extremely rapid and scar-free process, with re-epithelialization of the luminal epithelium completed within 48 h of initiation of shedding. Following menstruation, the functionalis grows from the residual basalis layer during the proliferative phase under the influence of rising circulating estrogen levels. The regenerative capacity of the endometrium is attributed to stem/progenitor cells which reside in both the epithelial and stromal cell compartments of the basalis layer. Finding a definitive marker for endometrial epithelial progenitors (eEPCs) has proven difficult. A number of different markers have been suggested as putative progenitor markers including, N-cadherin, SSEA-1, AXIN2, SOX-9 and ALDH1A1, some of which show functional stem cell activity in in vitro assays. Each marker has a unique location(s) in the glandular epithelium, which has led to the suggestion that a differentiation hierarchy exists, from the base of epithelial glands in the basalis to the luminal epithelium lining the functionalis, where epithelial cells express different combinations of markers as they differentiate and move up the gland into the functionalis away from the basalis niche. Perivascular endometrial mesenchymal stem cells (eMSCs) can be identified by co-expression of PDGFRβ and CD146 or by a single marker, SUSD2. This review will detail the known endometrial stem/progenitor markers; their identity, location and known interactions and hierarchy across the menstrual cycle, in particular post-menstrual repair and estrogen-driven regeneration, as well as their possible contributions to menstruation-related disorders such as endometriosis and regeneration-related disorder Asherman's syndrome. We will also highlight new techniques that allow for a greater understanding of stem/progenitor cells' role in repair and regeneration, including 3D organoids, 3D slice cultures and gene sequencing at the single cell level. Since mouse models are commonly used to study menstruation, repair and regeneration we will also detail the mouse stem/progenitor markers that have been investigated in vivo.

A 3D endometrial organotypic model simulating the acute inflammatory decidualisation initiation phase with epithelial induction of the key endometrial receptivity marker, integrin αVβ3

STUDY QUESTION

Is it possible to develop a simplified physiological in vitro system representing the key cell-types associated with a receptive endometrial phenotype?

SUMMARY ANSWER

We present a new concept to investigate endometrial receptivity, with a 3D organotypic co-culture model to simulate an early and transient acute autoinflammatory decidual status that resolves in the induction of a receptive endometrial phenotype.

WHAT IS KNOWN ALREADY

Embryo implantation is dependent on a receptive uterine environment. Ovarian steroids drive post-ovulation structural and functional changes in the endometrium, which becomes transiently receptive for an implanting conceptus, termed the ‘window of implantation’, and dysregulation of endometrial receptivity is implicated in a range of reproductive, obstetric, and gynaecological disorders and malignancies. The interactions that take place within the uterine microenvironment during this time are not fully understood, and human studies are constrained by a lack of access to uterine tissue from specific time-points during the menstrual cycle. Physiologically relevant in vitro model systems are therefore fundamental for conducting investigations to better understand the cellular and molecular mechanisms controlling endometrial receptivity.

STUDY DESIGN, SIZE, DURATION

We conducted an in vitro cell culture study using human cell lines and primary human cells isolated from endometrial biopsy tissue. The biopsy tissue samples were obtained from three women attending gynaecological outpatient departments in NHS Lothian. The work was carried out between December 2016 and April 2019, at the MRC Centre for Reproductive Health, Queen’s Medical Research Institute, University of Edinburgh.

PARTICIPANTS/MATERIALS, SETTING, METHODS

An endometrial stromal cell (ESC) line, and endometrial epithelial cells (EECs) isolated from endometrial biopsy tissue and expanded in vitro by conditional reprogramming, were used throughout the study. Immunocytochemical and flow cytometric analyses were used to confirm epithelial phenotype following conditional reprogramming of EECs. To construct an endometrial organotypic co-culture model, ESCs were embedded within a 3D growth factor-reduced Matrigel structure, with a single layer of conditionally reprogrammed EECs seeded on top. Cells were stimulated with increasing doses of medroxyprogesterone acetate, cAMP and oestradiol, in order to induce ESC decidual transformation and endometrial receptivity. Decidual response and the induction of a receptive epithelial phenotype were assessed by immunocytochemical detection and quantitative in-cell western analyses, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

A transient up-regulation of the interleukin-33 receptor protein, ST2L, was observed in ESCs, indicating a transient autoinflammatory decidual response to the hormonal stimulation, known to induce receptivity gene expression in the overlying epithelium. Hormonal stimulation increased the EEC protein levels of the key marker of endometrial receptivity, integrin αVβ3 (n = 8; *P < 0.05; ***P < 0.0001). To our knowledge, this is the first demonstration of a dedicated endometrial organotypic model, which has been developed to investigate endometrial receptivity, via the recapitulation of an early decidual transitory acute autoinflammatory phase and induction of an epithelial phenotypic change, to represent a receptive endometrial status.

LIMITATIONS, REASONS FOR CAUTION

This simplified in vitro ESC-EEC co-culture system may be only partly representative of more complex in vivo conditions.

WIDER IMPLICATIONS OF THE FINDINGS

The 3D endometrial organotypic model presented here may offer a valuable tool for investigating a range of reproductive, obstetric, and gynaecological disorders, to improve outcomes for assisted reproductive technologies, and for the development of advances in contraceptive methods.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported in part by a Medical Research Council Centre Grant (project reference MR/N022556/1). R.F. was the recipient of a Moray Endowment award and a Barbour Watson Trust award. C.-J.L. is a Royal Society of Edinburgh Personal Research Fellow, funded by the Scottish Government. The authors have no conflicts of interest to declare.

Conditioned medium derived from seminal extracellular vesicles-exposed endometrial stromal cells induces inflammatory cytokine secretion by macrophages

OBJECTIVE

Seminal plasma (SP) contains large numbers of sub-cellular structures called extracellular vesicles (EV) which have been postulated to have immunological functions due to their bioactive contents including proteins and small non-coding RNAs. Although the response of endometrial cells to seminal EV (SEV) is recently being elucidated, the impact of these signaling vesicles on stroma-immune crosstalk is still unknown. Herein, we aimed to investigate the effect of conditioned medium (CM) derived from SEV-exposed endometrial stromal cells (eSC) on cytokine secretion by macrophages.

STUDY DESIGN

SEV were isolated from SP samples of healthy donors and characterized by common methods needed for EV characterization, including size determination by dynamic light scattering (DLS), transmission electron microscopy (TEM), and western blot analysis of EV markers. Endometrial biopsies were obtained from healthy individuals and eSC were isolated and characterized. EV internalization assay was performed by labeling the SEV with PKH67 green fluorescent dye. Then, the eSC were exposed to SEV and the CM was collected. Finally, the CM from SEV-exposed eSC was added to the macrophage culture and the level of inflammatory (interleukin (IL)-1α and IL-6) and anti-inflammatory (IL-10) cytokines were measured in the culture supernatant of macrophages.

RESULTS

The results demonstrated that the CM derived from SEV-exposed eSC induce IL-1α and IL-6 secretion by the macrophages, while the secretion of IL-10 was reduced.

CONCLUSION

Our results support the idea that the stroma-immune interaction is affected by SEV. This effect may be a part of immunoregulatory function of SP inside upper female genital tract and have an obvious impact during peri-implantation period.

Women with polycystic ovary syndrome present with altered endometrial expression of stanniocalcin-1†

Stanniocalcin-1 (STC-1) is a pro-survival factor that protects tissues against stressors, such as hypoxia and inflammation. STC-1 is co-expressed with the endometrial receptivity markers, and recently endometrial STC-1 was reported to be dysregulated in endometriosis, a condition linked with endometrial progesterone resistance and inflammation. These features are also common in the endometrium in women with polycystic ovary syndrome (PCOS), the most common endocrine disorder in women. Given that women with PCOS present with subfertility, pregnancy complications, and increased risk for endometrial cancer, we investigated endometrial STC-1 expression in affected women. Endometrial biopsy samples were obtained from women with PCOS and controls, including samples from overweight/obese women with PCOS before and after a 3-month lifestyle intervention. A total of 98 PCOS and 85 control samples were used in immunohistochemistry, reverse-transcription polymerase chain reaction, or in vitro cell culture. STC-1 expression was analyzed at different cycle phases and in endometrial stromal cells (eSCs) after steroid hormone exposure. The eSCs were also challenged with 8-bromo-cAMP and hypoxia for STC-1 expression. The findings indicate that STC-1 expression is not steroid hormone mediated although secretory-phase STC-1 expression was blunted in PCOS. Lower expression seems to be related to attenuated STC-1 response to stressors in PCOS eSCs, shown as downregulation of protein kinase A activity. The 3-month lifestyle intervention did not restore STC-1 expression in PCOS endometrium. More studies are warranted to further elucidate the mechanisms behind the altered endometrial STC-1 expression and rescue mechanism in the PCOS endometrium.

In Silico, In Vitro, and In Vivo Analysis Identifies Endometrial Circadian Clock Genes in Recurrent Implantation Failure

CONTEXT

Previous work has demonstrated the role of the circadian clock in ovarian steroid hormone synthesis and attributed embryo implantation failure associated with arrhythmic circadian clock genes to insufficient ovarian-derived progesterone synthesis. Research on expression of core circadian clock genes in the endometrium itself and possible roles in compromised endometrial receptivity and recurrent implantation failure (RIF) are limited.

OBJECTIVE

We aimed to assess the core circadian clock gene profiling in human endometrium across the menstrual cycle and the possible gene interaction networks in the endometrial receptivity of window of implantation (WOI) as well as RIF.

METHODS

The study was initially an in silico study, with confirmatory lab-based data from primary human endometrial stromal cells (hESCs) as well as endometrial biopsies obtained from 60 women undergoing gynecological surgery in a clinical research center. The study included 30 RIF women and 30 age-matched and body mass index-matched controls.

RESULTS

Initial data mining and bioinformatics analysis of human endometrial microarray datasets across the menstrual cycle and between RIF women versus controls demonstrated the varied expression of core circadian clock genes across menstrual cycle, including the key role of PER2 in WOI and RIF. A PER2-centered network was investigated in the regulation of endometrial receptivity. We also confirmed the evidently increased mRNA expression of SHTN1, RXFP1, KLF5, and STEAP4 in the endometrium of RIF women, displaying the same trend as PER2 did, without any changes in MT1E and FKBP5. Treatment of PER2 siRNA in hESCs verified the positive regulation of PER2 to SHTN1, KLF5, and STEAP4.

CONCLUSION

Aberrant expression of endometrial PER2 might contribute to impaired endometrial receptivity and development of RIF via regulating SHTN1, KLF5, and STEAP4.

Seminal plasma promotes decidualization of endometrial stromal fibroblasts in vitro from women with and without inflammatory disorders in a manner dependent on interleukin-11 signaling

STUDY QUESTION

Do seminal plasma (SP) and its constituents affect the decidualization capacity and transcriptome of human primary endometrial stromal fibroblasts (eSFs)?

SUMMARY ANSWER

SP promotes decidualization of eSFs from women with and without inflammatory disorders (polycystic ovary syndrome (PCOS), endometriosis) in a manner that is not mediated through semen amyloids and that is associated with a potent transcriptional response, including the induction of interleukin (IL)-11, a cytokine important for SP-induced decidualization.

WHAT IS KNOWN ALREADY

Clinical studies have suggested that SP can promote implantation, and studies in vitro have demonstrated that SP can promote decidualization, a steroid hormone-driven program of eSF differentiation that is essential for embryo implantation and that is compromised in women with the inflammatory disorders PCOS and endometriosis.

STUDY DESIGN, SIZE, DURATION

This is a cross-sectional study involving samples treated with vehicle alone versus treatment with SP or SP constituents. SP was tested for the ability to promote decidualization in vitro in eSFs from women with or without PCOS or endometriosis (n = 9). The role of semen amyloids and fractionated SP in mediating this effect and in eliciting transcriptional changes in eSFs was then studied. Finally, the role of IL-11, a cytokine with a key role in implantation and decidualization, was assessed as a mediator of the SP-facilitated decidualization.

PARTICIPANTS/MATERIALS, SETTING, METHODS

eSFs and endometrial epithelial cells (eECs) were isolated from endometrial biopsies from women of reproductive age undergoing benign gynecologic procedures and maintained in vitro. Assays were conducted to assess whether the treatment of eSFs with SP or SP constituents affects the rate and extent of decidualization in women with and without inflammatory disorders. To characterize the response of the endometrium to SP and SP constituents, RNA was isolated from treated eSFs or eECs and analyzed by RNA sequencing (RNAseq). Secreted factors in conditioned media from treated cells were analyzed by Luminex and ELISA. The role of IL-11 in SP-induced decidualization was assessed through Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-9-mediated knockout experiments in primary eSFs.

MAIN RESULTS AND THE ROLE OF CHANCE

SP promoted decidualization both in the absence and presence of steroid hormones (P < 0.05 versus vehicle) in a manner that required seminal proteins. Semen amyloids did not promote decidualization and induced weak transcriptomic and secretomic responses in eSFs. In contrast, fractionated SP enriched for seminal microvesicles (MVs) promoted decidualization. IL-11 was one of the most potently SP-induced genes in eSFs and was important for SP-facilitated decidualization.

LARGE SCALE DATA

RNAseq data were deposited in the Gene Expression Omnibus repository under series accession number GSE135640.

LIMITATIONS, REASONS FOR CAUTION

This study is limited to in vitro analyses.

WIDER IMPLICATIONS OF THE FINDINGS

Our results support the notion that SP promotes decidualization, including within eSFs from women with inflammatory disorders. Despite the general ability of amyloids to induce cytokines known to be important for implantation, semen amyloids poorly signaled to eSFs and did not promote their decidualization. In contrast, fractionated SP enriched for MVs promoted decidualization and induced a transcriptional response in eSFs that overlapped with that of SP. Our results suggest that SP constituents, possibly those associated with MVs, can promote decidualization of eSFs in an IL-11-dependent manner in preparation for implantation.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by NIH (R21AI116252, R21AI122821 and R01AI127219) to N.R.R. and (P50HD055764) to L.C.G. The authors declare no conflict of interest.

Endometrial regeneration with endometrial epithelium: homologous orchestration with endometrial stroma as a feeder

BACKGROUND

Thin endometrium adversely affects reproductive success rates with fertility treatment. Autologous transplantation of exogenously prepared endometrium can be a promising therapeutic option for thin endometrium; however, endometrial epithelial cells have limited expansion potential, which needs to be overcome in order to make regenerative medicine a therapeutic strategy for refractory thin endometrium. Here, we aimed to perform long-term culture of endometrial epithelial cells in vitro.

METHODS

We prepared primary human endometrial epithelial cells and endometrial stromal cells and investigated whether endometrial stromal cells and human embryonic stem cell-derived feeder cells could support proliferation of endometrial epithelial cells. We also investigated whether three-dimensional culture can be achieved using thawed endometrial epithelial cells and endometrial stromal cells.

RESULTS

Co-cultivation with the feeder cells dramatically increased the proliferation rate of the endometrial epithelial cells. We serially passaged the endometrial epithelial cells on mouse embryonic fibroblasts up to passage 6 for 4 months. Among the human-derived feeder cells, endometrial stromal cells exhibited the best feeder activity for proliferation of the endometrial epithelial cells. We continued to propagate the endometrial epithelial cells on endometrial stromal cells up to passage 5 for 81 days. Furthermore, endometrial epithelium and stroma, after the freeze-thaw procedure and sequential culture, were able to establish an endometrial three-dimensional model.

CONCLUSIONS

We herein established a model of in vitro cultured endometrium as a potential therapeutic option for refractory thin endometrium. The three-dimensional culture model with endometrial epithelial and stromal cell orchestration via cytokines, membrane-bound molecules, extracellular matrices, and gap junction will provide a new framework for exploring the mechanisms underlying the phenomenon of implantation. Additionally, modified embryo culture, so-called "in vitro implantation", will be possible therapeutic approaches in fertility treatment.

Progesterone modulates adhesion molecules in uterine epithelial cells and in vitro embryo production in buffalo

This study was undertaken to evaluate the role of progesterone (P4) in modulation of the expression profile of adhesion-related molecules in uterine epithelial cells (UECs) and in vitro blastocyst production in buffalo. UECs were isolated from slaughterhouse-derived uteri by enzymatic treatment, and cells were characterized by immunocytochemistry (ICC) and PCR assays. The well-characterized UECs were exposed to different concentrations of P4 (0, 0.314, 3.14 and 6.28 ng/ml) along with the basal level of oestradiol for 6 days. Thereafter, the relative mRNA expression of different biomolecules such as mucin 1 (MUC1), osteopontin, integrin alpha (α3, α6 and αV) and beta (β1 and β3) subunits, progesterone receptor (PR) and oestrogen receptor, was evaluated. Further, day 2 post-insemination embryos were cultured in mSOF supplemented with or without P4. UECs were found positive for cytokeratin expression and negative for vimentin expression. Progesterone treatment significantly enhanced the mRNA expression of most of the transcripts compared with the control group, and correspondingly, the immunofluorescence depicted higher protein expression of all these molecules. Further, the long-term exposure of UECs to P4 downregulated the expression of PR and, concomitantly, MUC1. Progesterone supplementation to embryo culture medium significantly (p < .05) improved the blastocyst rate. The study demonstrates the role of P4 hormone in modulation of the expression of early implantation-related biomolecules in uterine epithelial cells; hence, adequate level of steroids is crucial for normal embryo development and its implantation.

Deregulation of the endometrial stromal cell secretome precedes embryo implantation failure

STUDY QUESTION

Is implantation failure following ART associated with a perturbed decidual response in endometrial stromal cells (EnSCs)?

SUMMARY ANSWER

Dynamic changes in the secretome of decidualizing EnSCs underpin the transition of a hostile to a supportive endometrial microenvironment for embryo implantation; perturbation in this transitional pathway prior to ART is associated with implantation failure.

WHAT IS KNOWN ALREADY

Implantation is the rate-limiting step in ART, although the contribution of an aberrant endometrial microenvironment in IVF failure remains ill defined.

STUDY DESIGN, SIZE, DURATION

In vitro characterization of the temporal changes in the decidual response of primary EnSCs isolated prior to a successful or failed ART cycle. An analysis of embryo responses to secreted cues from undifferentiated and decidualizing EnSCs was performed. The primary clinical outcome of the study was a positive urinary pregnancy test 14 days after embryo transfer.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Primary EnSCs were isolated from endometrial biopsies obtained prior to IVF treatment and cryopreserved. EnSCs from 10 pregnant and 10 non-pregnant patients were then thawed, expanded in culture, subjected to clonogenic assays, and decidualized for either 2 or 8 days. Transcript levels of decidual marker gene [prolactin (PRL), insulin-like growth factor binding protein 1 (IGFBP1) and 11β-hydroxysteroid dehydrogenase (HSD11B1)] were analysed using real-time quantitative PCR and temporal secretome changes of 45 cytokines, chemokines and growth factors were measured by multiplex suspension bead immunoassay. The impact of the EnSC secretome on human blastocyst development was scored morphologically; and embryo secretions in response to EnSC cues analyzed by multiplex suspension bead immunoassay.

MAIN RESULTS AND THE ROLE OF CHANCE

Clonogenicity and induction of decidual marker genes were comparable between EnSC cultures from pregnant and non-pregnant group groups (P > 0.05). Analysis of 23 secreted factors revealed that successful implantation was associated with co-ordinated secretome changes in decidualizing EnSCs, which were most pronounced on Day 2 of differentiation: 17 differentially secreted proteins on Day 2 of decidualization relative to undifferentiated (Day 0) EnSCs (P < 0.05); 11 differentially secreted proteins on Day 8 relative to Day 2 (P < 0.05); and eight differentially secreted proteins on Day 8 relative to Day 0 (P < 0.05). By contrast, failed implantation was associated with a disordered secretome response. Blastocyst development was compromised when cultured for 24 h in medium conditioned by undifferentiated EnSCs when compared to decidualizing EnSCs. Analysis of the embryo microdroplets revealed that human blastocysts mount a secretory cytokine response to soluble decidual factors produced during the early (Day 2) but not late phase (Day 8) of differentiation. The embryo responses to secreted factors from decidualizing EnSCs were comparable between the pregnant and non-pregnant group (P > 0.05).

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

Although this study uses primary EnSCs and human embryos, caution is warranted when extrapolating the results to the in vivo situation because of the correlative nature of the study and limited sample size.

WIDER IMPLICATIONS OF THE FINDINGS

Our finding raises the prospect that endometrial analysis prior to ART could minimize the risk of treatment failure.

STUDY FUNDING AND COMPETING INTEREST(S)

This work was supported by funds from the Biomedical Research Unit in Reproductive Health, a joint initiative of the University Hospitals Coventry & Warwickshire NHS Trust and Warwick Medical School, the University of Nottingham and Nurture Fertility, and the National Medical Research Council, Singapore (NMRC/BNIG14NOV023), the "Instituut voor Innovatie door Wetenschap en Technologie" (IWT, Flanders, Belgium), the "Fonds voor Wetenschappelijk Onderzoek" (FWO, Flanders, Belgium) and the "Wetenschappelijk Fonds Willy Gepts" (WFWG, UZ Brussel). The authors have declared that no conflict of interest exists.

Regulation of inflammatory mediator expression in bovine endometrial cells: effects of lipopolysaccharide, interleukin 1 beta, and tumor necrosis factor alpha

An abnormal uterine environment can influence maternal-fetal communication, conception rate and disrupt normal embryo development, thereby affecting fertility and the reproductive performance of dairy cows. Animal variability means that development of endometrial cell lines with appropriate characteristic are required. We evaluated the effect of an infectious agent (i.e., bacterial lipopolysaccharide; LPS) and proinflammatory mediators (i.e., Interleukin 1 beta; IL-1β, and tumor necrosis factor alpha; TNFα) on inflammatory mediator gene expression and production by bovine endometrial epithelial (bEEL) and stromal (bCSC) cell lines. Expression of CXCL8/IL8, IL1A, IL1B, and IL6 cytokine genes was significantly upregulated in both epithelial and stromal cells when treated with LPS and IL-1β. LPS treatment of epithelial cells (compared with treatment by IL-1β and TNFα) exhibited greater CXCL8/IL8, IL1A, IL1B, and IL6 cytokine gene expression. Whereas, in stromal cells, IL-1β treatment (compared with LPS and TNFα) exhibited greater CXCL8/IL8, IL1A, IL1B, and IL6 cytokine gene expression. Interestingly, bEEL and bCSC cells treated with IL-1β increased IL1B gene expression, suggesting that IL-1β may act unusually in an autocrine-positive feedback loop. Cytokine production was stimulated by these agents in both cell types. We suggest that the characteristics of these two cell lines make them excellent tools for the study of intrauterine environment.

Interconnected Microphysiological Systems for Quantitative Biology and Pharmacology Studies

Microphysiological systems (MPSs) are in vitro models that capture facets of in vivo organ function through use of specialized culture microenvironments, including 3D matrices and microperfusion. Here, we report an approach to co-culture multiple different MPSs linked together physiologically on re-useable, open-system microfluidic platforms that are compatible with the quantitative study of a range of compounds, including lipophilic drugs. We describe three different platform designs – “4-way”, “7-way”, and “10-way” – each accommodating a mixing chamber and up to 4, 7, or 10 MPSs. Platforms accommodate multiple different MPS flow configurations, each with internal re-circulation to enhance molecular exchange, and feature on-board pneumatically-driven pumps with independently programmable flow rates to provide precise control over both intra- and inter-MPS flow partitioning and drug distribution. We first developed a 4-MPS system, showing accurate prediction of secreted liver protein distribution and 2-week maintenance of phenotypic markers. We then developed 7-MPS and 10-MPS platforms, demonstrating reliable, robust operation and maintenance of MPS phenotypic function for 3 weeks (7-way) and 4 weeks (10-way) of continuous interaction, as well as PK analysis of diclofenac metabolism. This study illustrates several generalizable design and operational principles for implementing multi-MPS “physiome-on-a-chip” approaches in drug discovery.

In vitro evidence that platelet-rich plasma stimulates cellular processes involved in endometrial regeneration

PURPOSE

The study aims to test the hypothesis that platelet-rich plasma (PRP) stimulates cellular processes involved in endometrial regeneration relevant to clinical management of poor endometrial growth or intrauterine scarring.

METHODS

Human endometrial stromal fibroblasts (eSF), endometrial mesenchymal stem cells (eMSC), bone marrow-derived mesenchymal stem cells (BM-MSC), and Ishikawa endometrial adenocarcinoma cells (IC) were cultured with/without 5% activated (a) PRP, non-activated (na) PRP, aPPP (platelet-poor-plasma), and naPPP. Treatment effects were evaluated with cell proliferation (WST-1), wound healing, and chemotaxis Transwell migration assays. Mesenchymal-to-epithelial transition (MET) was evaluated by cytokeratin and vimentin expression. Differential gene expression of various markers was analyzed by multiplex Q-PCR.

RESULTS

Activated PRP enhanced migration of all cell types, compared to naPRP, aPPP, naPPP, and vehicle controls, in a time-dependent manner (p < 0.05). The WST-1 assay showed increased stromal and mesenchymal cell proliferation by aPRP vs. naPRP, aPPP, and naPPP (p < 0.05), while IC proliferation was enhanced by aPRP and aPPP (p < 0.05). There was no evidence of MET. Expressions of MMP1, MMP3, MMP7, and MMP26 were increased by aPRP (p < 0.05) in eMSC and eSF. Transcripts for inflammation markers/chemokines were upregulated by aPRP vs. aPPP (p < 0.05) in eMSC and eSF. No difference in estrogen or progesterone receptor mRNAs was observed.

CONCLUSIONS

This is the first study evaluating the effect of PRP on different human endometrial cells involved in tissue regeneration. These data provide an initial ex vivo proof of principle for autologous PRP to promote endometrial regeneration in clinical situations with compromised endometrial growth and scarring.

Local remodeling of synthetic extracellular matrix microenvironments by co-cultured endometrial epithelial and stromal cells enables long-term dynamic physiological function

Mucosal barrier tissues, comprising a layer of tightly-bonded epithelial cells in intimate molecular communication with an underlying matrix-rich stroma containing fibroblasts and immune cells, are prominent targets for drugs against infection, chronic inflammation, and other disease processes. Although human in vitro models of such barriers are needed for mechanistic studies and drug development, differences in extracellular matrix (ECM) needs of epithelial and stromal cells hinder efforts to create such models. Here, using the endometrium as an example mucosal barrier, we describe a synthetic, modular ECM hydrogel suitable for 3D functional co-culture, featuring components that can be remodeled by cells and that respond dynamically to sequester local cell-secreted ECM characteristic of each cell type. The synthetic hydrogel combines peptides with off-the-shelf reagents and is thus accessible to cell biology labs. Specifically, we first identified a single peptide as suitable for initial attachment of both endometrial epithelial and stromal cells using a 2D semi-empirical screen. Then, using a co-culture system of epithelial cells cultured on top of gel-encapsulated stromal cells, we show that inclusion of ECM-binding peptides in the hydrogel, along with the integrin-binding peptide, leads to enhanced accumulation of basement membrane beneath the epithelial layer and more fibrillar collagen matrix assembly by stromal cells over two weeks in culture. Importantly, endometrial co-cultures composed of either cell lines or primary cells displayed hormone-mediated differentiation as assessed by morphological changes and secretory protein production. A multiplex analysis of apical cytokine and growth factor secretion comparing cell lines and primary cells revealed strikingly different patterns, underscoring the importance of using primary cell models in analysis of cell-cell communication networks. In summary, we define a "one-size-fits-all" synthetic ECM that enables long-term, physiologically responsive co-cultures of epithelial and stromal cells in a mucosal barrier format.

Niche matters: The comparison between bone marrow stem cells and endometrial stem cells and stromal fibroblasts reveal distinct migration and cytokine profiles in response to inflammatory stimulus

Objective

Intrinsic inflammatory characteristics play a pivotal role in stem cell recruitment and homing through migration where the subsequent change in niche has been shown to alter these characteristics. The bone marrow mesenchymal stem cells (bmMSCs) have been demonstrated to migrate to the endometrium contributing to the stem cell reservoir and regeneration of endometrial tissue. Thus, the aim of the present study was to compare the inflammation-driven migration and cytokine secretion profile of human bmMSCs to endometrial mesenchymal stem cells (eMSCs) and endometrial fibroblasts (eSFs).

Materials and methods

The bmMSCs were isolated from bone marrow aspirates through culturing, whereas eMSCs and eSFs were FACS-isolated. All cell types were tested for their surface marker, proliferation profiles and migration properties towards serum and inflammatory attractants. The cytokine/chemokine secretion profile of 35 targets was analysed in each cell type at basal level along with lipopolysaccharide (LPS)-induced state.

Results

Both stem cell types, bmMSCs and eMSCs, presented with similar stem cell surface marker profiles as well as possessed high proliferation and migration potential compared to eSFs. In multiplex assays, the secretion of 16 cytokine targets was detected and LPS stimulation expanded the cytokine secretion pattern by triggering the secretion of several targets. The bmMSCs exhibited higher cytokine secretion of vascular endothelial growth factor (VEGF)-A, stromal cell-derived factor-1 alpha (SDF)-1α, interleukin-1 receptor antagonist (IL-1RA), IL-6, interferon-gamma inducible protein (IP)-10, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)1α and RANTES compared to eMSCs and/or eSFs after stimulation with LPS. The basal IL-8 secretion was higher in both endometrial cell types compared to bmMSCs.

Conclusion

Our results highlight that similar to bmMSCs, the eMSCs possess high migration activity while the differentiation process towards stromal fibroblasts seemed to result in loss of stem cell surface markers, minimal migration activity and a subtler cytokine profile likely contributing to normal endometrial function.

Isolation of Mouse Endometrial Epithelial and Stromal Cells for In Vitro Decidualization

Decidualization is a progesterone-dependent differentiation process of endometrial stromal cells and is a prerequisite for successful embryo implantation. Although many efforts have been made to reveal the underlying mechanisms of decidualization, the exact signaling between the epithelial cells that are in contact with the embryo and the underlying stromal cells remains poorly understood. Therefore, studying decidualization in a way that takes both the epithelial and stromal cells into account could improve our knowledge about the molecular details of decidualization. For this purpose, in vivo models of artificial decidualization are physiologically the most relevant; however, manipulation of intercellular communication is limited. Currently, in vitro cultures of endometrial stromal cells are being used to investigate the modulation of decidualization by several signaling molecules. Conventionally, human or mouse endometrial stromal cells are used. However, the availability of human samples is very often limited. Furthermore, the use of murine tissues is accompanied with variety in the method of culturing. This study presents a validated and standardized method to obtain pure Endometrial Epithelial Cell (EEC) and Stromal Cell (ESC) cultures using adult intact mice treated with estrogen for three consecutive days. The protocol is optimized to improve the yield, viability, and purity of the cells and was further extended in order to study decidualization in a coculture of EEC and ESC. This model may be suitable to exploit the importance of both cell types in decidualization and to evaluate the contribution of significant signaling molecules secreted by EEC or ESC during the intercellular communication.

Mucosal stromal fibroblasts markedly enhance HIV infection of CD4+ T cells

Understanding early events of HIV transmission within mucosal tissues is vital for developing effective prevention strategies. Here, we report that primary stromal fibroblasts isolated from endometrium, cervix, foreskin, male urethra, and intestines significantly increase HIV infection of CD4+ T cells-by up to 37-fold for R5-tropic HIV and 100-fold for X4-tropic HIV-without themselves becoming infected. Fibroblasts were more efficient than dendritic cells at trans-infection and mediate this response in the absence of the DC-SIGN and Siglec-1 receptors. In comparison, mucosal epithelial cells secrete antivirals and inhibit HIV infection. These data suggest that breaches in the epithelium allow external or luminal HIV to escape an antiviral environment to access the infection-favorable environment of the stromal fibroblasts, and suggest that resident fibroblasts have a central, but previously unrecognized, role in HIV acquisition at mucosal sites. Inhibiting fibroblast-mediated enhancement of HIV infection should be considered as a novel prevention strategy.

Expression and localization of ARTEMIN in the bovine uterus and embryos

Artemin a member of the glial cell line-derived neurotrophic factor (GDNF) family is present in mice and human preimplantation embryos, and reproductive tract, during early pregnancy promoting embryo development in vitro. The presence of artemin in cattle embryos and reproductive tract, however, is unknown. In the present work we identified for first time artemin in bovine uterine fluid (UF) (Western blot), endometrium (RT-PCR, Western blot and immunohistochemistry) and embryos (RT-PCR and immunohistochemistry) during early preimplantation development. In addition, GFRalpha3, a component of the artemin receptor was localized in blastocysts produced in vitro. Individually developing embryos released ARTEMIN in culture medium and triggered ARTEMIN mRNA down-regulation in epithelial cells from endometrial cell cultures. Our results suggest that ARTEMIN derived from early embryos and maternal reproductive tract may exert important roles during early development in cattle.

Cryopreservation and recovery of human endometrial epithelial cells with high viability, purity, and functional fidelity

OBJECTIVE

To develop a protocol for cryopreservation and recovery of human endometrial epithelial cells (eECs) retaining molecular and functional characteristics of endometrial epithelium in vivo.

DESIGN

In vitro study using human endometrial cells.

SETTING

University research laboratory.

PATIENT(S)

Endometrial biopsies were obtained from premenopausal women undergoing benign gynecologic procedures.

INTERVENTION(S)

Primary eECs were cryopreserved in 1% fetal bovine serum/10% dimethylsulfoxide in Defined Keratinocyte Serum-Free Medium (KSFM). Recovered cells were observed for endometrial stromal fibroblast (eSF) contamination and subsequently evaluated for morphology, gene expression, and functional characteristics of freshly cultured eECs and in vivo endometrial epithelium.

MAIN OUTCOME MEASURE(S)

Analysis of eEC morphology and the absence of eSF contamination; evaluation of epithelial-specific gene and protein expression; assessment of epithelial polarity.

RESULT(S)

Endometrial epithelial cells recovered after cryopreservation (n = 5) displayed epithelial morphology and expressed E-cadherin (CDH1), occludin (OCLN), claudin1 (CLDN1), and keratin18 (KRT18). Compared with eSF, recovered eECs displayed increased (P<.05) expression of epithelial-specific genes AREG, CDH1, DEFB4A, MMP7, and WNT7A, while exhibiting low-to-undetectable (P<.05) stromal-specific genes COL6A3, HOXA11, MMP2, PDGFRB, and WNT5A. Recovered eECs secreted levels of cytokines and growth factors similarly to freshly cultured eECs. Recovered eECs could form a polarized monolayer with high transepithelial electrical resistance (TER) and impermeability to small molecules, and expressed apical/basolateral localization of CDH1 and apical localization of OCLN.

CONCLUSION(S)

We have developed a protocol for cryopreservation of eECs in which recovered cells after thawing demonstrate morphologic, transcriptomic, and functional characteristics of human endometrial epithelium in vivo.

Unexpected Inflammatory Effects of Intravaginal Gels (Universal Placebo Gel and Nonoxynol-9) on the Upper Female Reproductive Tract: A Randomized Crossover Study

Intravaginal anti-HIV microbicides could provide women with a self-controlled means for HIV prevention, but results from clinical trials have been largely disappointing. We postulated that unrecognized effects of intravaginal gels on the upper female reproductive tract might contribute to the lower-than-expected efficacy of HIV microbicides. Our objective was to study the effects of intravaginal gels on the immune microenvironment of the cervix and uterus. In this randomized crossover study, 27 healthy female volunteers used a nightly application of intravaginal nonoxynol-9 (N9) gel as a "failed" microbicide or the universal placebo gel (UPG) as a "safe" gel (intervention cycles), or nothing (control cycle) from the end of menses to the mid-luteal phase. At a specific time-point following ovulation, all participants underwent sample collection for measurements of T-cell phenotypes, gene expression, and cytokine/chemokine protein concentrations from 3 anatomic sites above the vagina: the cervical transformation zone, the endocervix and the endometrium. We used hierarchical statistical models to estimate mean (95% CI) intervention effects, for N9 and UPG relative to control. Exposure to N9 gel and UPG generated a common "harm signal" that included transcriptional up-regulation of inflammatory genes chemokine (C-C motif) ligand 20 (macrophage inflammatory factor-3alpha) and interleukin 8 in the cervix, decreased protein concentrations of secretory leukocyte protease inhibitor, and transcriptional up-regulation of inflammatory mediators glycodelin-A and osteopontin in the endometrium. These results need to be replicated with a larger sample, but underscore the need to consider the effects of microbicide agents and gel excipients on the upper female reproductive tract in studies of vaginal microbicides.

Endometrial stromal fibroblasts from women with polycystic ovary syndrome have impaired progesterone-mediated decidualization, aberrant cytokine profiles and promote enhanced immune cell migration in vitro

STUDY QUESTION

Do endometrial stromal fibroblasts (eSF) in women with polycystic ovary syndrome (PCOS) (eSFpcos) exhibit altered estrogen and/or progesterone (P4) responses, which may explain some of the adverse reproductive outcomes and endometrial pathologies in these women?

SUMMARY ANSWER

In vitro, eSF from women with PCOS exhibit an aberrant decidualization response and concomitant changes in pro-inflammatory cytokine, chemokine and matrix metalloproteinase (MMP) release and immune cell chemoattraction. In vivo these aberrations may result in suboptimal implantation and predisposition to endometrial cancer.

WHAT IS KNOWN ALREADY

The endometrium in women with PCOS has several abnormalities including progesterone (P4) resistance at the gene expression level, likely contributing to subfertility, pregnancy complications and increased endometrial cancer risk in PCOS women.

STUDY DESIGN, SIZE, DURATION

Prospective, university-based, case-control, in vitro study.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cultures of eSFPCOS (n = 12, Rotterdam and NIH criteria) and eSFControl (Ctrl) (n = 6, regular cycle length, no signs of hyperandrogenism) were treated with vehicle, estradiol (E2, 10 nM) or E2P4 (10 nM/1 μM) for 14 days. Progesterone receptor (PGR) mRNA was assessed with quantitative real-time PCR (qRT-PCR) and eSF decidualization was confirmed by insulin-like growth factor-binding protein-1 (IGFBP-1) transcript and protein expression. Fractalkine (CX3CL1), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL) 6, 8 and 11, macrophage chemoattractant protein (MCP) 1 and 3, CCL5 (RANTES) and MMPs (MMP1, 2, 3, 7, 9, 10 and 12) were measured in conditioned media by Luminex multiplex assays, and chemotactic activity of the conditioned media was tested in a migration assay using CD14+ monocyte and CD4+ T-cell migration assay. Effects of IL-6 (0.02, 0.2, 2 or 20 ng/ml) or IL-8 (0.04, 0.4, 4, or 40 ng/ml) or combination (0.2 ng/ml IL-6 and 4.0 ng/ml IL-8) on 14-d decidualization were also tested. ANOVA with pre-planned contrasts was used for statistical analysis.

MAIN RESULTS AND THE ROLE OF CHANCE

Hormonal challenge with E2P4 to induce decidualization revealed two distinct subsets of eSFPCOS. Eight eSFPCOS (dPCOS) and all eSFCtrl (dCtrl) cultures showed a normal decidualization response to E2P4 as determined by morphology and IGFBP-1 secretion. However, 4 eSFPCOS cultures showed blunted decidualization (ndPCOS) in morphological assessment and low IGFBP-1 levels even though all three groups exhibited normal estrogen-mediated increase in PGR expression. Interestingly dPCOS had decreased IL-6 and GM-SCF secretion compared with dCtrl, whereas the ndPCOS cultures showed increased IL-6 and 8, MCP1, RANTES and GM-CSF secretion at base-line and/or in response to E2 or E2P4 compared with dCtrl and/or dPCOS. Furthermore, even though PGR expression was similar in all three groups, P4 inhibition of MMP secretion was attenuated in ndPCOS resulting in higher MMP2 and 3 levels. The conditioned media from ndPCOS had increased chemoattractic activity compared with dCtrl and dPCOS media. Exogenously added IL-6 and/or 8 did not inhibit decidualization in eSFCtrl indicating that high levels of these cytokines in ndPCOS samples were not likely a cause for the aberrant decidualization.

LIMITATIONS, REASONS FOR CAUTION

This is an in vitro study with a small sample size, utilizing stromal cell cultures from proliferative and secretory phase endometrium. The effect of PCOS on endometrial epithelium, another major histoarchitectural cell compartment of the endometrium, was not evaluated and should be considered in future studies. Furthermore, results obtained should also be confirmed in a larger data set and with mid/late secretory phase in vivo samples and models.

WIDER IMPLICATIONS OF THE FINDINGS

The alterations seen in ndPCOS may contribute to endometrial dysfunction, subfertility and pregnancy complications in PCOS women. The results emphasize the importance of understanding immune responses related to the implantation process and normal endometrial homeostasis in women with PCOS.

STUDY FUNDING/COMPETING INTERESTS

Sigrid Juselius Foundation, Academy of Finland, Finnish Medical Foundation, Orion-Farmos Research Foundation (to T.T.P.), the NIH Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) U54HD 055764-07 Specialized Cooperative Centers Program in Reproduction and Infertility Research (to L.C.G.), the NICHD the Ruth L. Kirschstein National Research Service Awards grant 1F32HD074423-03 (to J.C.C.). The authors have no competing interests.

Isolation and Culture of Human Endometrial Epithelial Cells and Stromal Fibroblasts

Purification and culture of endometrial epithelial cells (eEC) and stromal fibroblasts (eSF) from endometrial biopsies allows for downstream cell-specific in vitro studies. The utility of this protocol is the ease with which cells are purified without contamination from unwanted cell types, and the ability to use patient-paired eEC and eSF in experiments. These methods have been previously published, but here the protocol has been updated for maximum efficiency.

Tissue-engineered endometrial model for the study of cell-cell interactions

Endometrial stromal and epithelial cell cross talk is known to influence many of the dynamic changes that occur during the menstrual cycle. We modified our previous model and embedded telomerase-immortalized human endometrial stromal cells and Ishikawa adenocarcinoma epithelial cells in a collagen-Matrigel hydrogel to create a tissue-engineered model of the endometrium. Comparisons of single and cocultured cells examined communication between endometrial stromal and epithelial cells, which were cultured with 0 or 10 nmol/L 17β estradiol; conditioned medium was used to look at the production of paracrine factors. Using this model, we were able to identify the changes in interleukin 6 (IL-6) and active matrix metalloproteinase 2, which appear to be due to paracrine signaling and differences in transforming growth factor β1 (TGF-β1) that do not appear to be due to paracrine signaling. Moreover, IL-6, TGF-β1, and DNA content were also affected by the presence of estradiol in many of the tissues. These results indicate that paracrine and endocrine signaling are involved in human endometrial responses and support the use of coculture models to further investigate cell-cell and cell-matrix interactions.

Seminal plasma induces global transcriptomic changes associated with cell migration, proliferation and viability in endometrial epithelial cells and stromal fibroblasts

STUDY QUESTION

How does seminal plasma (SP) affect the transcriptome of human primary endometrial epithelial cells (eEC) and stromal fibroblasts (eSF)?

SUMMARY ANSWER

Exposure of eEC and eSF to SP in vitro increases expression of genes and secreted proteins associated with cellular migration, proliferation, viability and inhibition of cell death.

WHAT IS KNOWN ALREADY

Studies in both humans and animals suggest that SP can access and induce physiological changes in the upper female reproductive tract (FRT), which may participate in promoting reproductive success.

STUDY DESIGN, SIZE, DURATION

This is a cross sectional study involving control samples versus treatment. SP (pooled from twenty donors) was first tested for dose- and time-dependent cytotoxic effects on eEC and eSF (n = 4). As exposure of eEC or eSF to 1% SP for 6 h proved to be non-toxic, a second set of eEC/eSF samples (n = 4) was treated under these conditions for transcriptome, protein and functional analysis. With a third set of samples (n = 3), we further compared the transcriptional response of the cells to SP versus fresh semen.

PARTICIPANTS/MATERIALS, SETTING, METHODS

eEC and eSF were isolated from endometrial biopsies from women of reproductive age undergoing benign gynecologic procedures and maintained in vitro. RNA was isolated and processed for microarray studies to analyze global transcriptomic changes. Secreted factors in conditioned media from SP-treated cells were analyzed by Luminex and for the ability to stimulate migration of CD14+ monocytes and CD4+ T cells.

MAIN RESULTS AND THE ROLE OF CHANCE

Pathway identifications were determined using the Z-scoring system in Ingenuity Pathways Analysis (Z scores ≥|1.5|). SP induced transcriptomic changes (P < 0.05) associated with promoting leukocyte and endothelial cell recruitment, and proliferation of eEC and eSF. Cell viability pathways were induced, while those associated with cell death were suppressed (P < 0.05). SP and fresh semen induced similar sets of pathways, suggesting that SP can model the signaling effects of semen in the endometrium. SP also induced secretion of pro-inflammatory and pro-chemotactic cytokines, as well as pro-angiogenic and proliferative growth factors (P < 0.05) in both eEC and eSF. Finally, functional assays revealed that conditioned media from SP-treated eEC and eSF significantly increased (P < 0.05) chemotaxis of CD14+ monocytes and CD4+ T cells.

LIMITATIONS, REASONS FOR CAUTION

This study is limited to in vitro analyses of the effects of SP on endometrial cells. In addition, the measured response to SP was conducted in the absence of the ovarian hormones estradiol and progesterone, as well as epithelial-stromal paracrine signaling. While this study focused on establishing the baseline cellular response of endometrial cells to SP, future work should assess how hormone signaling in the presence of appropriate paracrine interactions affects SP-induced genes in these cells.

WIDER IMPLICATIONS OF THE FINDINGS

The results of this study support previous findings that SP and semen contain bioactive factors capable of eliciting chemotactic responses in the uterus, which can lead to recruitment of leukocytes to the endometrium. Future directions will explore if similar changes in gene expression do indeed occur after coitus in vivo, and how the signaling cascades initiated by SP in the endometrium can affect reproductive success, female reproductive health and susceptibility to sexually transmitted diseases. The gene list provided by the transcriptome analysis reported here should prove a valuable resource for understanding the response of the upper FRT to SP exposure.

STUDY FUNDING/COMPETING INTEREST(S)

This project was supported by NIH AI083050-04 (W.C.G./L.C.G.); NIH U54HD 055764 (L.C.G.); NIH 1F32HD074423-02 (J.C.C.); DOD W81XWH-11-1-0562 (W.C.G.); NIH 5K12-DK083021-04, NIH 1K99AI104262-01A1, The UCSF Hellman Award (N.R.R.). The authors have nothing to disclose.