Trophoblast cells exhibit differential responses to laminin isoforms

Mechanistic insights into the development of severe fetal growth restriction

Fetal growth restriction (FGR), which most commonly results from suboptimal placental function, substantially increases risks for adverse perinatal and long-term outcomes. The only "treatment" that exists is delivery, which averts stillbirth but does not improve outcomes in survivors. Furthermore, the potential long-term consequences of FGR to the fetus, including cardiometabolic disorders, predispose these individuals to developing FGR in their future pregnancies. This creates a multi-generational cascade of adverse effects stemming from a single dysfunctional placenta, and understanding the mechanisms underlying placental-mediated FGR is critically important if we are to improve outcomes and overall health. The mechanisms behind FGR remain unknown. However, placental insufficiency derived from maldevelopment of the placental vascular systems is the most common etiology. To highlight important mechanistic interactions within the placenta, we focus on placental vascular development in the setting of FGR. We delve into fetoplacental angiogenesis, a robust and ongoing process in normal pregnancies that is impaired in severe FGR. We review cellular models of FGR, with special attention to fetoplacental angiogenesis, and we highlight novel integrin-extracellular matrix interactions that regulate placental angiogenesis in severe FGR. In total, this review focuses on key developmental processes, with specific focus on the human placenta, an underexplored area of research.

Epidermal growth factor induces a trophectoderm lineage transcriptome resembling that of human embryos during reconstruction of blastoids from extended pluripotent stem cells

OBJECTIVES

This study aims to optimize the human extended pluripotent stem cell (EPSC) to trophectoderm (TE)-like cell induction with addition of EGF and improve the quality of the reconstructing blastoids.

MATERIALS AND METHODS

TE-like cells were differentiated from human EPSCs. RNA-seq data analysis was performed to compare with TE-like cells from multiple human pluripotent stem cells (hPSCs) and embryos. A small-scale compound selection was performed for optimizing the TE-like cell induction and the efficiency was characterized using TE-lineage markers expression by immunofluorescence stanning. Blastoids were generated by using the optimized TE-like cells and the undifferentiated human EPSCs through three-dimensional culture system. Single-cell RNA sequencing was performed to investigate the lineage segregation of the optimized blastoids to human blastocysts.

RESULTS

TE-like cells derived from human EPSCs exhibited similar transcriptome with TE cells from embryos. Additionally, TE-like cells from multiple naive hPSCs exhibited heterogeneous gene expression patterns and signalling pathways because of the incomplete silencing of naive-specific genes and loss of imprinting. Furthermore, with the addition of EGF, TE-like cells derived from human EPSCs enhanced the TE lineage-related signalling pathways and exhibited more similar transcriptome to human embryos. Through resembling with undifferentiated human EPSCs, we elevated the quality and efficiency of reconstructing blastoids and separated more lineage cells with precise temporal and spatial expression, especially the PE lineage.

CONCLUSION

Addition of EGF enhanced TE lineage differentiation and human blastoids reconstruction. The optimized blastoids could be used as a blastocyst model for simulating early embryonic development.

Decrease of laminin-511 in the basement membrane due to photoaging reduces epidermal stem/progenitor cells

Daily sunlight exposure damages the epidermal basement membrane (BM) and disrupts epidermal homeostasis. Inter-follicular epidermal stem cells (IFE-SCs) regulate epidermal proliferation and differentiation, which supports epidermal homeostasis. Here, we examine how photoaging affects the function of IFE-SCs and we identify key components in their cellular environment (niche). We found that sun-exposed skin showed a decrease of MCSP-positive and β1-integrin-positive cells concomitantly with a decrease of laminin-511 at the dermal-epidermal junction (DEJ), as compared with sun-protected skin. Higher levels of laminin-511 were associated with not only increased efficiency of colony formation, but also higher expression levels of MCSP as well as other stem cell markers such as Lrig1, ITGB1, CD44, CD46, DLL1, and K15 in keratinocytes from skin of 12- to 62-year-old subjects. UVB exposure to cultured human skin impaired laminin-511 integrity at the dermal-epidermal junction and reduced MCSP-positive basal epidermal cells as well as K15-positive cells. Combined treatment with matrix metalloproteinase and heparanase inhibitors protected the integrity of laminin-511 and inhibited the reduction of MCSP-positive cells and K15-positive cells. These results suggest that photoaging may reduce the levels of MCSP-positive and K15-positive epidermal stem/progenitor cells in the epidermis via loss of laminin-511 at the dermal-epidermal junction.

The role of extracellular matrix in normal and pathological pregnancy: Future applications of microphysiological systems in reproductive medicine

IMPACT STATEMENT

Extracellular matrix in the womb regulates the initiation, progression, and completion of a healthy pregnancy. The composition and physical properties of extracellular matrix in the uterus and at the maternal-fetal interface are remodeled at each gestational stage, while maladaptive matrix remodeling results in obstetric disease. As in vitro models of uterine and placental tissues, including micro-and milli-scale versions of these organs on chips, are developed to overcome the inherent limitations of studying human development in vivo, we can isolate the influence of cellular and extracellular components in healthy and pathological pregnancies. By understanding and recreating key aspects of the extracellular microenvironment at the maternal-fetal interface, we can engineer microphysiological systems to improve assisted reproduction, obstetric disease treatment, and prenatal drug safety.

Integrins functioning in uterine endometrial stromal and epithelial cells in estrus

Here, as a basic study in the construction of a non-cellular niche that supports artificial organization of three-dimensional endometrial tissue, we defined the types of integrin heterodimers that are expressed transcriptionally, translationally and functionally in endometrial stromal (ES) and endometrial epithelial (EE) cells isolated from the mouse uterus in estrus. Gene and protein expression of integrin subunits were analyzed at the transcriptional and translational level by real-time PCR and fluorescent immunoassay, respectively. Moreover, the functionality of integrin heterodimers was confirmed by attachment and antibody inhibition assays. Itga2, Itga5, Itga6, Itga9, Itgav, Itgb1, Itgb3 and Itgb5 in ES cells, and Itga2, Itga5, Itga6, Itga7, Itga9, Itgav, Itgb1, Itgb3, Itgb4, Itgb5 and Itga6 and in EE cells showed significantly higher transcriptional levels than the other integrin subunits. Furthermore, translational expression of the total integrin α and β subunit genes that showed increased transcription was determined in ES and EE cells. ES cells showed significantly increased adhesion to collagen I, fibronectin and vitronectin, and functional blocking of integrin α2, α5 or αV significantly inhibited adhesion to these molecules. Moreover, EE cells showed significantly increased adhesion to collagen I, fibronectin, laminin and vitronectin, and functional blocking of integrin α2, α5, α6 or αV significantly inhibited adhesion to these molecules. Accordingly, we confirmed that integrin α2β1, α5β1, αVβ1, αVβ3 and/or αVβ5, and integrin α2β1, α5β1, α6β1 and/or α6β4, αVβ1, αVβ3 and/or αVβ5, actively function on the surface of ES and EE cells from mouse uterus in estrus phase, respectively.

Integrin α6β1 Expressed in ESCs Instructs the Differentiation to Endothelial Cells

Adhesion of embryonic stem cells (ESCs) to the extracellular matrix may influence differentiation potential and cell fate decisions. Here, we investigated the inductive role of binding of integrin α6β1 expressed in mouse (m)ESCs to laminin-1 (LN1) in mediating the differentiation of ESCs to endothelial cells (ECs). We observed that α6β1 binding to LN1 was required for differentiation to ECs. α6β1 functioned by recruiting the adaptor tetraspanin protein CD151, which activated FAK and Akt signaling and mediated the EC lineage-specifying transcription factor Er71. In contrast, association of the ESC-expressed α3β1, another highly expressed LN1 binding integrin, with CD151, prevented α6β1-mediated differentiation. CD151 thus functioned as a bifurcation router to direct ESCs toward ECs when α6β1 associated with CD151, or prevented transition to ECs when α3β1 associated with CD151. These observations were recapitulated in mice in which α6 integrin or CD151 knockdown reduced the expression of Er71-regulated angiogenesis genes and development of blood vessels. Thus, interaction of α6β1 in ESCs with LN1 activates α6β1/CD151 signaling which programs ESCs toward the EC lineage fate.

Uterine micro-environment and estrogen-dependent regulation of osteopontin expression in mouse blastocyst

Embryo implantation is a highly synchronized bioprocess between an activated blastocyst and a receptive uterus. In mice, successful implantation relies on the dynamic interplay of estrogen and progesterone; however, the key mediators downstream of these hormones that act on blastocyst competency and endometrium receptivity acquisition are largely unknown. In this study, we showed that the expression of osteopontin (OPN) in mouse blastocysts is regulated by ovarian estrogen and uterine micro-environment. OPN mRNA is up-regulated in mouse blastocyst on day 4 of pregnancy, which is associated with ovarian estrogen secretion peak. Hormone treatment in vivo demonstrated that OPN expression in a blastocyst is regulated by estrogen through an estrogen receptor (ER). Our results of the delayed and activated implantation model showed that OPN expression is induced after estrogen injection. While estrogen treatment during embryo culture in vitro showed less effect on OPN expression, the tubal ligation model on day 3 of pregnancy confirmed that the regulation of estrogen on OPN expression in blastocyst might, through some specific cytokines, have existed in a uterine micro-environment. Collectively, our study presents that estrogen regulates OPN expression and it may play an important role during embryo implantation by activating blastocyst competence and facilitating the endometrium acceptable for active blastocyst.

Laminin α5 guides tissue patterning and organogenesis

Laminins (LM) are extracellular matrix molecules that contribute to and are required for the formation of basement membranes. They participate in the modulation of epithelial/mesenchymal interactions and are implicated in organogenesis and maintenance of organ homeostasis. Among the LM molecules, the LM α5 chain (LMα5) is one of the most widely distributed LM in the developing and mature organism. Its presence in some basement membranes during embryogenesis is absolutely required for maintenance of basement membrane integrity and thus for proper organogenesis. LMα5 also regulates the expression of genes important for major biological processes, in part by repressing or activating signaling pathways, depending upon the physiological context.

Dissecting the first transcriptional divergence during human embryonic development

The trophoblast cell lineage is specified early at the blastocyst stage, leading to the emergence of the trophectoderm and the pluripotent cells of the inner cell mass. Using a double mRNA amplification technique and a comparison with transcriptome data on pluripotent stem cells, placenta, germinal and adult tissues, we report here some essential molecular features of the human mural trophectoderm. In addition to genes known for their role in placenta (CGA, PGF, ALPPL2 and ABCG2), human trophectoderm also strongly expressed Laminins, such as LAMA1, and the GAGE Cancer/Testis genes. The very high level of ABCG2 expression in trophectoderm, 7.9-fold higher than in placenta, suggests a major role of this gene in shielding the very early embryo from xenobiotics. Several genes, including CCKBR and DNMT3L, were specifically up-regulated only in trophectoderm, indicating that the trophoblast cell lineage shares with the germinal lineage a transient burst of DNMT3L expression. A trophectoderm core transcriptional regulatory circuitry formed by 13 tightly interconnected transcription factors (CEBPA, GATA2, GATA3, GCM1, KLF5, MAFK, MSX2, MXD1, PPARD, PPARG, PPP1R13L, TFAP2C and TP63), was found to be induced in trophectoderm and maintained in placenta. The induction of this network could be recapitulated in an in vitro trophoblast differentiation model.

Nucleus pulposus cell-matrix interactions with laminins

The cells of the nucleus pulposus (NP) region of the intervertebral disc play a critical role in this tissue's generation and maintenance, and alterations in NP cell viability, metabolism, and phenotype with aging may be key contributors to progressive disc degeneration. Relatively little is understood about the phenotype of NP cells, including their cell-matrix interactions which may modulate phenotype and survival. Our previous work has identified strong and region-specific expression of laminins and laminin cell-surface receptors in immature NP tissues, suggesting laminin cell-matrix interactions are uniquely important to the biology of NP cells. Whether these observed tissue-level laminin expression patterns reflect functional adhesion behaviors for these cells is not known. In this study, we examined NP cell-matrix interactions with specific matrix ligands, including various laminin isoforms, using quantitative assays of cell attachment, spreading, and adhesion strength. NP cells were found to attach in higher numbers and exhibited rapid cell spreading and higher resistance to detachment force on two laminin isoforms (LM-511,LM-332) identified to be uniquely expressed in the NP region, as compared to another laminin isoform (LM-111) and several other matrix ligands (collagen, fibronectin). Additionally, NP cells were found to attach in higher numbers to laminins as compared to cells isolated from the disc's annulus fibrosus region. These findings confirm that laminin and laminin receptor expression documented in NP tissues translates into unique functional NP cell adhesion behaviors that may be useful tools for in vitro cell culture and biomaterials that support NP cells.

Transcription factor CCAAT enhancer-binding protein beta (C/EBPbeta) regulates the formation of a unique extracellular matrix that controls uterine stromal differentiation and embryo implantation

During implantation, the uterine stromal cells undergo terminal differentiation into decidual cells, which support the proper progression of maternal-embryo interactions to successful establishment of pregnancy. The decidual cells synthesize extracellular matrix (ECM) components, such as laminins and collagens, which assemble into a unique basal lamina-like network that surrounds these cells. The functional significance of this matrix during implantation is unknown. We previously showed that the transcription factor CCAAT enhancer-binding protein β (C/EBPβ) critically regulates decidualization in the mouse. We now provide evidence that C/EBPβ directly controls the Lamc1 gene, which encodes a predominant laminin constituent of the ECM produced by the decidual cells. Suppression of Lamc1 expression in mouse primary endometrial stromal cells prevented the assembly of this ECM and impaired stromal differentiation. Attenuation of expression of integrin β1, a major constituent of the integrin receptors targeted by decidual laminins, also inhibited this differentiation process. Disruption of laminin-integrin interactions led to impaired activation of the focal adhesion kinase, an integrin-mediated regulator of cytoskeletal remodeling during decidualization. To further analyze the role of the decidual ECM in modulating maternal-embryo interactions, we monitored trophoblast invasion into differentiating uterine stromal monolayers, using a co-culture system. Silencing of stromal Lamc1 expression, which prevented formation of the basal lamina-like matrix, resulted in marked reduction in trophoblast outgrowth. Collectively, our findings identified C/EBPβ as a critical regulator of the unique ECM that controls decidual cell architecture and differentiation, and it provided new insights into the mechanisms by which the uterine stromal microenvironment controls the progression of embryo implantation.

From mouse egg to mouse embryo: polarities, axes, and tissues

This review describes the three classical models (mosaic, positional, and polarization) proposed to explain blastocyst formation and summarizes the evidence concerning them. It concludes that the polarization model incorporates elements of the other two models and best explains most known information. I discuss key requirements of a molecular basis for the generation and stabilization of polarity and identify ezrin/E-cadherin, PAR proteins, and Cdx2 as plausible key molecular players. I also discuss the idea of a network process operating to build cell allocations progressively into committed differences. Finally, this review critically considers the possibility of developmental information being encoded within the oocyte and zygote. No final decision can be reached on a mechanism of action underlying any encoded information, but a cell interaction process model is preferred over one that relies solely on differential inheritance.

Tubulointerstitial nephritis antigen-like 1 is expressed in extraembryonic tissues and interacts with laminin 1 in the Reichert membrane at postimplantation in the mouse

Tubulointerstitial nephritis antigen-like 1 (Tinagl1, also known as adrenocortical zonation factor 1 [AZ-1] or lipocalin 7) has been cloned from mouse adrenocortical cells and is known to be closely associated with zonal differentiation of adrenocortical cells. In cell culture systems, TINAGL1 is a matricellular protein that interacts with both structural matrix proteins and cell surface receptors. However, the physiological roles of TINAGL1 and regulation of its expression are still not clearly understood. In the present study, the expression and localization of TINAGL1 in peri-implantation mouse embryos was examined. During preimplantation, the expression of both Tinagl1 mRNA and TINAGL1 protein was increased just prior to implantation. In blastocysts, TINAGL1 expression was localized to the trophectoderm. Using a progesterone-treated, delayed-implantation model, TINAGL1 was found to be upregulated in implantation-competent blastocysts after estrogen treatment. During postimplantation, TINAGL1 expression was restricted to extraembryonic regions. Marked expression was detected in the Reichert membrane on Embryonic Days 6.5 (E6.5) and E7.5. Colocalization of laminin 1 and TINAGL1 was also examined. Using an anti-LAMA1 antibody, colocalization of LAMA1 and TINAGL1 was observed in postimplantation embryos. Colocalization was also detected in the Reichert membrane. Immunoprecipitation analysis determined that LAMA1 and TINAGL1 interact in embryos on E7.5. These results demonstrate that after implantation, TINAGL1 is an extraembryonic tissue-specific protein. In particular, TINAGL1 is a novel component of the Reichert membrane that interacts with laminin 1. These results suggest that TINAGL1 most likely plays a physical and physiological role in embryo development at postimplantation.

Human ES cells and a blastocyst from one embryo: exciting science but conflicting ethics?

In this issue of Cell Stem Cell, Chung et al. (2008) remove a single blastomere to generate a human embryonic stem cell (hESC) line without prejudicing the development of the biopsied embryo. Their method stimulates new ideas about hESC formation, but ethicopolitical concerns remain.

Mechanotransduction from the ECM to the genome: Are the pieces now in place?

A multitude of biochemical signaling processes have been characterized that affect gene expression and cellular activity. However, living cells often need to integrate biochemical signals with mechanical information from their microenvironment as they respond. In fact, the signals received by shape alone can dictate cell fate. This mechanotrasduction of information is powerful, eliciting proliferation, differentiation, or apoptosis in a manner dependent upon the extent of physical deformation. The cells internal "prestressed" structure and its "hardwired" interaction with the extra-cellular matrix (ECM) appear to confer this ability to filter biochemical signals and decide between divergent cell functions influenced by the nature of signals from the mechanical environment. In some instances mechanical signaling through the tissue microenvironment has been shown to be dominant over genomic defects, imparting a normal phenotype on cells that otherwise have transforming genetic lesions. This mechanical control of phenotype is postulated to have a central role in embryogenesis, tissue physiology as well as the pathology of a wide variety of diseases, including cancer. We will briefly review studies showing physical continuity between the external cellular microenvironment and the interior of the cell nucleus. Newly characterized structures, termed nuclear envelope lamina spanning complexes (NELSC), and their interactions will be described as part of a model for mechanical transduction of extracellular cues from the ECM to the genome.

Investigation of the effects of heparin and low molecular weight heparin on E-cadherin and laminin expression in rat pregnancy by immunohistochemistry

BACKGROUND

Heparin and low molecular weight heparin (LMWH) are used widely to improve the pregnancy outcome in women with thrombophilia, miscarriage, recurrent miscarriage and fetal death. This study was designed to investigate the effects of heparin and LMWHs, enoxaparin and tinzaparin, on E-cadherin and laminin expression in placental and decidual tissues in rat pregnancy.

METHODS

Wistar albino female rats (n = 48) were randomly assigned to four study groups (normal saline, heparin, enoxaparin and tinzaparin) in the preconceptional period. Tissue sections of placenta and decidua were immunohistochemically examined for the expression of E-cadherin and laminin.

RESULTS

E-cadherin placental staining score of heparin group was significantly lower and E-cadherin decidual staining score of heparin and enoxaparin groups were significantly lower than control group. There were no significant differences in placental and decidual laminin staining scores among the study groups.

CONCLUSIONS

Heparin and enoxaparin can reduce E-cadherin expression but not laminin expression in rat pregnancy. They might modulate trophoblast invasion. We suggest that this is the possible underlying mechanism involving in improvement of trophoblast invasion by the use of heparin and LMWH in patients with the history of miscarriage.

Cell pellets from dental papillae can reexhibit dental morphogenesis and dentinogenesis

We isolated dental papilla mesenchymal cells (DPMCs) from different rat incisor germs at the late bell stage and incubated them as cell pellets in polypropylene tubes. In vitro pellet culture of DPMCs presented several crucial characteristics of odontoblasts, as indicated by accelerated mineralization, positive immunostaining for dentin sialophosphoprotein and dentin matrix protein 1, and expression of dentin sialophosphoprotein mRNA. The allotransplantation of these pellets into renal capsules was also performed. Despite the absence of dental epithelial components, dissociated DPMCs with a complete loss of positional information rapidly underwent dentinogenesis and morphogenesis, and formed a cusp-like dentin-pulp complex containing distinctive odontoblasts, predentin, dentin, and dentinal tubules. These results imply that DPMCs at the late bell stage can reexhibit the dental morphogenesis and dentinogenesis by themselves, and epithelial-mesenchymal interactions at this stage may not be indispensable. Furthermore, different DPMC populations from the similar stage may keep the same developmental pattern.