Inadequate implantation and placentation is associated with miscarriage and placental insufficiency. The decidual environment is thought to regulate trophoblast invasion, however this is poorly defined in humans. We aimed to determine the effect of decidualization on trophoblast function. In vitro decidualized primary human endometrial stromal cells (HESC) significantly enhanced first-trimester extravillous trophoblast (EVT) (6-8-weeks gestation) adhesion, outgrowth/invasion. In EVTs from 10 to 12-weeks gestation this effect was absent (adhesion, invasion) or reversed (outgrowth). HESC conditioned media had no effect on trophoblast MMP9 production/activity. Decidualization regulated EVT function in a gestational-dependent manner. This study highlights the importance of trophoblast-decidual synchrony.

Interleukin (IL)11 is a crucial factor for human trophoblast function and placentation. Elevated levels are associated with pregnancy complications including preeclampsia, intrauterine growth restriction (IUGR) and preterm birth. However, the regulation of IL11 in the placenta has not been investigated. We examined the effect of pro-inflammatory cytokines IL1β and TNFα, as well as low oxygen tension (2%) on IL11 levels in first trimester placental villous explants. IL1β upregulated IL11 mRNA and protein, while TNFα and low oxygen had no effect. Using mass spectrometry, we identified protein disulfide isomerase 4 (PDIA4) in IL11-treated first trimester human placental explants (100 ng/ml, 24 h, n = 3), but not PBS control tissues. PDIA4 is a member of the PDI family, also known as endoplasmic reticulum (ER) stress protein (ERP)72. We previously identified GRP78 (a master regulator for ER stress) in human placenta for the first time and demonstrated that IL11 up-regulates GRP78 in the placenta. In this report, we demonstrated that IL11 upregulates PDIA4 protein in human placental villous tissue, HTR8-SVneo trophoblasts (cell line) and in vivo in IL11-treated mouse placenta. We aimed to determine whether IL11 upregulates other ER stress proteins in human first trimester placental villous. IL11 stimulated ERP44, but not GRP94, or PDI. Placental endoplasmic reticulum stress has been postulated in the pathophysiology of preeclampsia and IUGR, but its activation remains elusive. Together, these data suggest that IL11 could trigger an ER stress response in the placenta, which may contribute to obstetric complications such as preeclampsia.

During the establishment of pregnancy, extravillous trophoblast (EVT) must invade into the uterine decidua to facilitate decidual artery remodelling to create the placental blood supply. The local decidual environment is thought to regulate trophoblast invasion, however these interactions are poorly defined in humans. Recent evidence in women suggests impaired decidualization is associated with miscarriage and preeclampsia. Primary human endometrial stromal cells (HESC) and first trimester extravillous trophoblast (EVTs) were used to assess the effect of EVT-secreted factors on HESC decidualization, adhesion, proliferation and migration. We determined the role of profilin (PFN)1, an EVT-secreted factor, on HESC function and identified a downstream target of PFN1. EVT-secreted factors induced HESC decidualization and enhanced decidualized HESC adhesion, proliferation and migration. Recombinant PFN1 enhanced methoxyprogesterone acetate-induced HESC decidualization and proliferation. PFN1 down-regulated the expression of lipoxygenase arachidonate 5-lipoxygenase (ALOX5) in HESC and THP-1 macrophages. ALOX5 localised to decidual cells and CD68+macrophages in 1 st trimester decidua. This study demonstrated that EVT secretions, including PFN1, enhanced HESC decidualization and motility. This study has identified a new pathway that facilitates appropriate decidualization during the establishment of pregnancy.

To determine the chromosomal constitution of embryos failing to develop to a clinically viable blastocyst following extended culture in vitro and whether the morphokinetic behaviour of such embryos relates to their chromosomal content. Prospective analysis of morphokinetic and chromosomal data for non-viable embryos following independent determination of their unsuitability for clinical use. Embryos were cultured in an Embryoscope time lapse incubator. After six days in culture embryos not suitable for transfer or freezing, due to cleavage arrest, multinucleation, failure to cavitate, cellular degeneration or failure to form a blastocyst of sufficient quality for clinical use, were subjected to whole genome amplification and Next Generation Sequencing. Interpretable results were obtained from 136 embryos. Embryos deemed unsuitable for clinical use displayed an aneuploidy rate of 95.6%, with only 6 embryos demonstrating an apparently euploid chromosomal complement. Of these 6 embryos, 3 were excluded from use due to absence of an inner cell mass and 3 due to inadequate trophectoderm formation and/or cellular degeneration. Of note, every embryo returning a euploid result underwent cavitation, leaving a 100% aneuploidy rate for embryos that failed to reach the blastocyst stage. When comparing embryos that did or did not attempt to cavitate (excluding triploid embryos), embryos failing to reach this stage contained on average twice the number of chromosomal errors (4.52 vs 2.25, p<0.0001). Unlike previously reported data utilising clinically viable blastocysts, these embryos exhibited a majority of monosomies over trisomies (65.8% vs 34.2%), likely reflecting the poorer developmental potential of monosomic embryos. Of interest, although triploid embryos are seen at the blastocyst stage, of the 7 triploid embryos identified in this cohort, 6 arrested at either one cell (3 embryos) or following their first cleavage division. The remaining triploid embryo reached cavitation but was of extremely poor quality. This suggests the rate of triploidy in early embryos may be significantly higher than that seen in clinical blastocyst samples. In addition to their standard aneuploidies, 15 embryos contained a segmental aneuploidy, however, in only one embryo was a segmental aneuploidy its only chromosomal error. Similarly, 29 embryos contained additional mosaic aneuploidies, below 50% increase or reduction but distinctly identifiable as a gain or loss. Embryos failing to reach the blastocyst stage in our culture system displayed universal aneuploidy, a significant finding when counseling our patients. The specific chromosomal errors in non-viable embryos do appear to impact their morphokinetic parameters, however, further work is required to elucidate these potential relationships.

STUDY QUESTION What is the in situ localization and function of hyperglycosylated hCG (hCG-H) in first trimester pregnancy tissues? SUMMARY ANSWER HCG-H localizes to the syncytiotrophoblast, cytotrophoblast and invasive extravillous trophoblast within the maternal decidua and promotes invasion during the first trimester of pregnancy. WHAT IS KNOWN ALREADY Serum levels of hCG-H decline dramatically throughout the first trimester of pregnancy. As hCG-H is produced by choriocarcinoma cells, it is proposed to regulate trophoblast invasion. STUDY DESIGN, SIZE, DURATION Tissues were collected from elective first trimester pregnancy terminations. Placental villous and decidua basalis were collected from Week 6 to Week 12 of gestation (n = 49). PARTICIPANTS/MATERIALS, SETTING, METHODS Tissues were collected from elective first trimester surgical pregnancy terminations to determine localization, abundance and function of hCG-H. Placental villous outgrowth studies determined the impact of neutralizing endogenous hCG-H on trophoblast function. Real-time proliferation, migration and invasion assays using JEG-3 choriocarcinoma cells further elucidated the role of hCG-H in trophoblast function. MAIN RESULTS AND THE ROLE OF CHANCE HCG-H localized to syncytiotrophoblast layer of the placental villous from gestational weeks 6-9; thereafter hCG-H localized as a discrete layer between syncytio- and cyto-trophoblast layers. Immunoreactive hCG-H was also observed within the cytotrophoblast layer in Week 7-8 of gestation. HCG-H abundance decreased within placental villous from Weeks 6-12 of gestation (n = 3 placentas per gestational weeks 6-12). HCG-H also localized to anchoring villi within maternal decidua, extravillous trophoblasts invading into the maternal decidua and endovascular trophoblasts remodeling maternal blood vessels. Treatment of primary first trimester villous explants with hCG-H neutralizing antibody reduced trophoblast outgrowth (n = 3 placentas, P < 0.05). Treatment of a trophoblast cell line with neutralizing antibody reduced trophoblast invasion (n = 4, P < 0.05) but did not affect migration or proliferation. LIMITATIONS, REASONS FOR CAUTION Functional invasion and migration assays performed using cell lines. Not possible to perform such assays with primary human material. WIDER IMPLICATIONS OF THE FINDINGS HCG-H is an important autocrine factor facilitating trophoblast invasion in the first trimester of pregnancy. Targeting hCG-H may prove useful in the treatment of pathologic pregnancies, such as ectopic pregnancies, or pregnancy complications including pre-eclampsia and gestational trophoblast diseases. STUDY FUNDING/COMPETING INTERESTS This work was supported by the Victorian Government Operational Infrastructure Support Program. J.E. is supported by NHMRC project grant #1047756, L.A.S. and E.D. by NHMRC Fellowships #1002018 and #550905 respectively and E.M. by an NHMRC Early Career Fellowship #611827. The authors have no conflicts of interest relating to this work.

Galectins regulate many cell functions important for placental development, however, the localization and role of galectin-7 is unknown. We hypothesized galectin-7 would be expressed by the placenta and detected in serum. Galectin-7 immunolocalized to syncytiotrophoblast, extravillous trophoblast and glandular epithelium in 1st trimester placenta/decidua and to syncytiotrophoblast and endothelial cells in term placenta, but in pre-eclamptic placentas endothelial staining was absent. Galectin-7 serum concentration was significantly elevated in women (weeks 10-12 and 17-20) who subsequently developed pre-eclampsia compared to women with healthy pregnancies. Galectin-7 is a promising prospective serum biomarker for pre-eclampsia and likely has important functions in placentation.

Glycosylation controls diverse protein functions and regulates various cellular phenotypes. Trophoblast invasion is essential for normal placental development. However, the role of glycosylation in human placenta throughout pregnancy is still unclear. The β-1,4-galactosyltransferase III (B4GALT3) has been found to regulate cancer cell invasion. We therefore investigated the expression of B4GALT3 in placenta and its roles in trophoblast.B4GALT3 protein expression was examined by quantitative Western blotting analysis in human placentas. For identification of B4GALT3-positive cells in normal human placenta, immunohistochemistry and immunofluorescence methods were used. To investigate effects of B4GALT3 on extravillous trophoblast (EVT)-like cell and primary EVT cells, we analyzed cell growth, adhesion, migration, and invasion in mock and B4GALT3-transfected cell.B4GALT3 expression significantly increased in third trimester human placenta. Immunostaining revealed that B4GALT3 expressed in placental villous cytotrophoblast, syncytiotrophoblast, and a subpopulation of EVT cells throughout pregnancy. Interestingly, we found increases in the expression level and percentage of B4GALT3-positive cells in third trimester EVT, but not in syncytiotrophoblasts and cytotrophoblasts of placental villi. Overexpression of B4GALT3 in HTR8/SVneo cells and primary trophoblast cells significantly suppressed cell migration. In addition, B4GALT3 suppressed cell invasion, and enhanced cell adhesion to laminin in HTR8/SVneo cells. Notably, we found that B4GALT3 modified glycans on β1-integrin, suppressed focal adhesion kinase (FAK) signaling, and enhanced β1-integrin degradation.We propose that B4GALT3-mediated glycosylation change not only enhances β1-integrin binding to laminin, but also attenuates β1-integrin stability. Our findings suggest that B4GALT3 is a critical regulator for suppressing EVT invasion in the late stages of pregnancy.

Introduction: Galectins are expressed at the fetal maternal interface and have multiple roles including during blastocyst implantation. The expression of galectin-7 however has not been investigated in the uterus. We aimed to localise galectin-7 to the endometrium of women with normal fertility and with a history of miscarriage and prospectively determine whether serum levels are altered in women who subsequently miscarry. We also investigated the role of galectin-7 on trophoblast endometrial epithelial cell adhesion.Methods: Immunohistochemistry localised galectin-7 to endometrium throughout the menstrual cycle in women (normal fertility or with history of miscarriage) and in first trimester implantation sites. Galectin-7 serum levels were determined by ELISA. We used both endometrial epithelial trophoblast cell lines and primary cells for cell cell adhesion experiments.Results: Galectin-7 immunolocalized to endometrial luminal and glandular epithelium in normally fertile women and was upregulated in epithelium and stroma of women with a history of miscarriage. Similarly, gelectin-7 serum levels were elevated at 6 weeks gestation in women who subsequently miscarried compared to gestation matched controls. Exogenous galectin-7 reduced endometrial epithelial trophoblast adhesion in cell-line and primary cell assays. However, when endometrial epithelial cells were isolated from women with endometrial disorders, galectin-7 increased epithelial trophoblast adhesion.Conclusions: Galectin-7 is produced by endometrial epithelium and is abnormally elevated in the endometrium of women with a history of miscarriage. Serum levels may be useful as a predictive biomarker of miscarriage. Our data suggests that galectin-7 facilitates adhesion of the embryo to the endometrium and elevated galectin-7 may result in abnormal adhesion. (C) 2014 Elsevier Ltd. All rights reserved.

During the establishment of pregnancy, a human blastocyst implants into the uterine endometrium to facilitate the formation of a functional placenta. Implantation involves the blastocyst adhering to the uterine luminal epithelium before the primitive syncytiotrophoblast and subsequently specialised cells, the extravillous trophoblast (EVT), invade into the decidua in order to engraft and remodel uterine spiral arteries, creating the placental blood supply at the end of the first trimester. Defects in EVT invasion lead to abnormal placentation and thus adverse pregnancy outcomes. The local decidual environment is thought to play a key role in regulating trophoblast invasion. Here we describe the major cell types present in the decidua during the first trimester of pregnancy and review what is known about their regulation of EVT invasion. Overall, the evidence suggests that in a healthy pregnancy almost all cell types in the decidua actively promote EVT invasion and, further, that reduced EVT invasion towards the end of the first trimester is regulated, in part, by the reduced invasive capacity of EVTs shown at this time.

Introduction: Ectopic pregnancy is unique to humans and a leading cause of maternal morbidity and mortality. The etiology remains unknown however factors regulating embryo implantation likely contribute. Leukemia inhibitory factor (LIF) has roles in extravillous trophoblast adhesion and invasion and is present in ectopic implantation sites. We hypothesised that LIF facilitates blastocyst adhesion/invasion in the Fallopian tube, contributing to ectopic pregnancy.Methods: We immunolocalised LIF receptor (R) in tubal ectopic pregnancy (N = 5). We used an oviduct cell line (OE-E6/E7) to model Fallopian tube epithelial cells and a trophoblast spheroid co-culture model (HTR-8/SVneo cell line formed spheroids) to model blastocyst attachment to the Fallopian tube. We examined LIF signaling pathways in OE-E6/E7 cells by Western blot. The effect of LIF and LIF inhibition (using a novel LIF inhibitor, PEGLA) on first-trimester placental outgrowth was determined.Results: LIFR localised to villous and extravillous trophoblast and Fallopian tube epithelium in ectopic pregnancy. LIF activated STAT3 but not the ERK pathway in OE-E6/E7 cells. LIF stimulated HTR-8/SVneo spheroid adhesion to OE-E6/E7 cells which was significantly reduced after PEGLA treatment. LIF promoted placental explants outgrowth, while co-treatment with PEGLA blocked outgrowth.Discussion: Our data suggests LIF facilitates the development of ectopic pregnancy by stimulating blastocyst adhesion and trophoblast outgrowth from placental explants. Ectopic pregnancy is usually diagnosed after 6 weeks of pregnancy, therefore PEGLA may be useful in targeting trophoblast growth/invasion.Conclusion: LIF may contribute to the development of ectopic pregnancies and that pharmacologically targeting LIF-mediated trophoblast outgrowth may be useful as a treatment for ectopic pregnancy. (C) 2013 Published by Elsevier Ltd.

INTRODUCTION:Trophoblast growth and invasion of the uterine endometrium are critical events during placentation and are tightly regulated by locally produced factors. Abnormal placentation can result in early miscarriage or preeclampsia and intrauterine growth restriction, leading to impaired fetal and/or maternal health. Chondroitin sulfate proteoglycan 4 (CSPG4) is involved in cancer cell migration and invasion, processes which are critical during placentation but unlike in cancer, trophoblast invasion is highly regulated. CSPG4 expression and function in trophoblast is unknown. We determined CSPG4 expression in human first trimester placenta and implantation sites, and investigated whether CSPG4 influenced proliferation, migration and invasion of a human extravillous trophoblast (EVT) cell line (HTR8/SVneo cells) as a model for extravillous trophoblast (EVT).METHODS AND RESULTS:Immunoreactive CSPG4 localized to EVT cells in the trophoblast shell, subpopulations of interstitial EVT cells within the decidua and cytotrophoblast cells in placental villi. In HTR8/SVneo cells, siRNA knockdown of CSPG4 stimulated proliferation and decreased migration/invasion. In primary first trimester placental villi explants two cytokines, interleukin 11 (IL11) and leukemia inhibitory factor (LIF) with known roles in trophoblast function, stimulated CSPG4 mRNA expression and immunoreactive protein in the cyotrophoblast.DISCUSSION AND CONCLUSION:This is the first demonstration of the production and function of CSPG4 in human placentation. These data suggest that locally produced CSPG4 stimulates human EVT migration and invasion and suggests that IL11 and LIF regulate villous cytotrophoblast differentiation towards the invasive phenotype at least in part via CSPG4.

Do human blastocysts which subsequently implant release factors that regulate endometrial epithelial cell gene expression and adhesion to facilitate endometrial receptivity?Blastocysts which subsequently implanted released factors that altered endometrial epithelial gene expression and facilitated endometrial adhesion while blastocysts that failed to implant did not.Human preimplantation blastocysts are thought to interact with the endometrium to facilitate implantation. Very little is known of the mechanisms by which this occurs and to our knowledge there is no information on whether human blastocysts facilitate blastocyst attachment to the endometrium.We used blastocyst-conditioned medium (BCM) from blastocysts that implanted (n 28) and blastocysts that did not implant (n 28) following IVF. Primary human endometrial epithelial cells (HEECs) (n 3 experiments) were treated with BCM and the effect on gene expression and adhesion to trophoblast cells determined. We compared the protein production of selected genes in the endometrium of women with normal fertility (n 40) and infertility (n 6) during the receptive phase.We used real-time RTPCR arrays containing 84 genes associated with the epithelial to mesenchymal transition. We validated selected genes by real-time RTPCR (n 3) and immunohistochemistry in the human endometrium (n 46). Adhesion assays were performed using HEECs and a trophoblast cell line (n 3).Blastocysts that implanted released factors that differentially altered mRNA levels for six genes (1.5 fold) compared with blastocysts that did not implant. A cohort of genes was validated at the protein level: SPARC and Jagged1 were down-regulated (P 0.01), while SNAI2 and TGF-B1 were up-regulated (P 0.05) by implanted compared with non-implanted BCM. Jagged-1 (P 0.05) and Snai-2 protein (P 0.01) showed cyclical changes in the endometrium across the cycle, and Jagged-1 staining differed in women with normal fertility versus infertility (only) (P 0.01). HEEC adhesion to a trophoblast cell line was increased after treatment with implanted BCM compared with untreated control (P 0.05).This is an in vitro study and it would be beneficial to validate our findings using a physiological model, such as mouse.This new strategy has identified novel pathways that may be important for human preimplantation blastocystendometrial interactions and opens the possibility of examining and manipulating specific pathways to improve implantation and pregnancy success.This study was supported by the National Health and Medical Research Council of Australia (Fellowship support 550905, 611827) and project grants by Monash IVF, Australia. There are no conflicts of interest to be declared.

BACKGROUND:Preimplantation cross-talk between a functional blastocyst and the endometrium is critical for successful blastocyst implantation. This interaction is mediated in part by endometrial cytokines/growth factors secreted by glandular epithelium into the uterine cavity. Recent evidence suggests that blastocyst-derived hCG may influence the endometrial milieu in conception cycles thereby enhancing receptivity and implantation success. This study investigated the effect of hCG on the secretory profile of a select cohort of 44 cytokines/growth factors from primary human endometrial epithelial cells (hEECs). These factors included those with both known and unknown roles during receptivity and implantation. The expression of one previously unknown hCG-regulated factor, fibroblast growth factor 2 (FGF2), in human endometrium and its effects on hEEC function were further examined.METHODS:hEECs isolated from endometrial biopsies collected from fertile cycling women (n = 15) were treated ± recombinant hCG (0.2-20 IU/ml) for 48 h and conditioned media was quantitatively analysed using Luminex™ multiplex technology. FGF2 was further investigated by immunohistochemistry, western blot and cell-adhesion assays.RESULTS:Of 44 cytokines/growth factors examined, 39 were produced by hEECs with a distinct profile. hCG (2 IU/ml) significantly increased the production of six factors, including those with known roles in receptivity and trophoblast function (interleukin-11), blastocyst migration and adhesion (CXCL10), blastocyst development (granulocyte macrophage colony-stimulating factor) and one unknown with respect to receptivity and implantation (FGF2). Up-regulation of known hCG-regulated proteins, vascular endothelial growth factor and leukaemia inhibitory factor, validated this study. Immunoreactive epithelial FGF2 increased across the menstrual cycle, being highest in secretory and first trimester pregnancy endometrium in vivo. FGF2 (100 ng/ml) stimulated phosphorylation of ERK1/2 in hEEC with no effect on ERK1/2 abundance and stimulated hEEC adhesion to fibronectin and collagen IV (components of blastocyst/trophectoderm extracellular matrix).CONCLUSIONS:These findings clearly support roles for hCG and FGF2 in the blastocyst-endometrial cross-talk important for endometrial receptivity and blastocyst implantation.

Interleukin-6 (IL-6) and interleukin-11 (IL-11) receptors (IL-6R and IL-11R, respectively) are both expressed in osteoclasts and transduce signal via the glycoprotein130 (gp130) co-receptor, but the physiological role of this pathway is unclear. To determine the critical roles of gp130 signalling in the osteoclast, we generated mice using cathepsin K Cre (CtskCre) to disrupt gp130 signalling in osteoclasts. Bone marrow macrophages from CtskCre.gp130f/f mice generated more osteoclasts in vitro than cells from CtskCre.gp130w/w mice; these osteoclasts were also larger and had more nuclei than controls. While no increase in osteoclast numbers was observed in vivo, osteoclasts on trabecular bone surfaces of CtskCre.gp130f/f mice were more spread out than in control mice, but had no functional defect detectable by serum CTX1 levels or trabecular bone cartilage remnants. However, trabecular osteoblast number and mineralising surfaces were significantly lower in male CtskCre.gp130f/f mice compared to controls, and this was associated with a significantly lower trabecular bone volume at 12 weeks of age. Furthermore, CtskCre.gp130f/f mice exhibited greatly suppressed periosteal bone formation at this age, indicated by significant reductions in both double-labelled surface and mineral apposition rate. By 26 weeks of age, CtskCre.gp130f/f mice exhibited narrower femora, with lower periosteal and endocortical perimeters than CtskCre.gp130w/w controls. Since IL-6 and IL-11R global knockout mice exhibited a similar reduction in femoral width, we also assessed periosteal bone formation in those strains, and found bone forming surfaces were also reduced in male IL-6 null mice. These data suggest that IL-6/gp130 signalling in the osteoclast is not essential for normal bone resorption in vivo, but maintains both trabecular and periosteal bone formation in male mice by promoting osteoblast activity through the stimulation of osteoclast-derived "coupling factors" and "osteotransmitters", respectively.

Decidualization is the differentiation of endometrial stromal cells into decidual cells. It is a critical process in embryo implantation, placentation and the establishment of pregnancy. Inadequate decidualization can lead to infertility, abnormal placentation and recurrent miscarriage. Endometrial leukemia inhibitory factor (LIF) is indispensible in blastocyst implantation in mice and dysregulated in infertile women. LIF is produced by 1st trimester decidual cells but its role in decidualization is not known. This study aimed to examine the role of LIF in human and mouse decidualization. Primary human endometrial stomal cells (HESC) were isolated and decidualized (D) by treatment with estradiol (E) +medroxyprogesterone acetate (MPA) for 14 days. HESC were also treated with E+MPA+/–LIF (0.5, 5, 50, 100 and 200 ng/mL) for 14 days. Prolactin secretion was used to assess the extent of decidualization (n = 6). D and non-D HESC were also treated with LIF (0.5, 5, 50, 100 and 200 ng/mL +/– LIF inhibitor) for 15min and the phosphorylation (p) of signal transducer and activator of transcription (STAT)3/STAT3 abundance was detected by Western blot (n = 4). RNA was isolated for analysis of LIF and LIF receptor (R) mRNA expression during decidualization (n = 4). HESC treated with E+MPA+LIF (50, 100 and 200 ng/mL) secreted more prolactin compared to cells treated with E+MPA alone (P < 0.05). LIF increased pSTAT3/STAT3 abundance in D and non-D cells while LIF+LIF inhibitor abolished pSTAT3/STAT3. LIF mRNA was downregulated while LIF-R mRNA increased during decidualization. In vivo, mated mice (n = 5) were injected intraperitoneally with a unique long acting LIF inhibitor post-implantation at day 4.5 of pregnancy and resulted in reduced decidualization compared to control. This is the first study to demonstrate that LIF promoted decidualization of HESC possibly via pSTAT3. It further suggested that LIF regulated decidualization in mice demonstrating a newly identified critical role for LIF in the establishment of pregnancy.

Blastocyst implantation into the endometrium is critical for the establishment of pregnancy and is tightly regulated by factors within the blastocyst-endometrial micro-environment. Implantation is a continuum involving blastocyst adhesion to the endometrial epithelium followed by trophoblast penetration of the epithelium. The trophoblast proliferates and invades through the endometrium, with a subpopulation acting to remodel the spiral arteries. Trophoblast-endometrial interactions in humans involve carefully orchestrated temporal and spatial alterations in factors that are critical for pregnancy success. Emerging evidence suggests important roles for locally produced cytokines including interleukin 11 and leukemia inhibitory factor in the various stages of implantation. This review focuses on the role of these cytokines in trophoblast-endometrial interactions during the establishment of human pregnancy.

Human trophoblast stem cells (hTSCs) derived from blastocysts and first-trimester cytotrophoblasts offer an unprecedented opportunity to study the placenta. However, access to human embryos and first-trimester placentas is limited, thus preventing the establishment of hTSCs from diverse genetic backgrounds associated with placental disorders. Here, we show that hTSCs can be generated from numerous genetic backgrounds using post-natal cells via two alternative methods: (1) somatic cell reprogramming of adult fibroblasts with OCT4, SOX2, KLF4, MYC (OSKM) and (2) cell fate conversion of naive and extended pluripotent stem cells. The resulting induced/converted hTSCs recapitulated hallmarks of hTSCs including long-term self-renewal, expression of specific transcription factors, transcriptomic signature, and the potential to differentiate into syncytiotrophoblast and extravillous trophoblast cells. We also clarified the developmental stage of hTSCs and show that these cells resemble day 8 cytotrophoblasts. Altogether, hTSC lines of diverse genetic origins open the possibility to model both placental development and diseases in a dish.