Decidua parietalis-derived mesenchymal stromal cells reside in a vascular niche within the choriodecidua

Mesenchymal Stem/Stromal Cells and Their Role in Oxidative Stress Associated with Preeclampsia

Preeclampsia (PE) is a serious medically important disorder of human pregnancy, which features de novo pregnancy-induced hypertension and proteinuria. The severe form of PE can progress to eclampsia, a convulsive, life-threatening condition. When placental growth and perfusion are abnormal, the placenta experiences oxidative stress and subsequently secretes abnormal amounts of certain pro-angiogenic factors (eg, PlGF) as well as anti-angiogenic factors (eg, sFlt-1) that enter the maternal circulation. The net effect is damage to the maternal vascular endothelium, which subsequently manifests as the clinical features of PE. Other than delivery of the fetus and placenta, curative treatments for PE have not yet been forthcoming, which reflects the complexity of the clinical syndrome. A major source of reactive oxygen species that contributes to the widespread maternal vascular endothelium damage is the PE-affected decidua. The role of decidua-derived mesenchymal stem/stromal cells (MSC) in normotensive and pathological placenta development is poorly understood. The ability to respond to an environment of oxidative damage is a "universal property" of MSC but the biological mechanisms that MSC employ in response to oxidative stress are compromised in PE. In this review, we discuss how MSC respond to oxidative stress in normotensive and pathological conditions. We also consider the possibility of manipulating the oxidative stress response of abnormal MSC as a therapeutic strategy to treat preeclampsia.

Perinatal Derivatives: Where Do We Stand? A Roadmap of the Human Placenta and Consensus for Tissue and Cell Nomenclature

Progress in the understanding of the biology of perinatal tissues has contributed to the breakthrough revelation of the therapeutic effects of perinatal derivatives (PnD), namely birth-associated tissues, cells, and secreted factors. The significant knowledge acquired in the past two decades, along with the increasing interest in perinatal derivatives, fuels an urgent need for the precise identification of PnD and the establishment of updated consensus criteria policies for their characterization. The aim of this review is not to go into detail on preclinical or clinical trials, but rather we address specific issues that are relevant for the definition/characterization of perinatal cells, starting from an understanding of the development of the human placenta, its structure, and the different cell populations that can be isolated from the different perinatal tissues. We describe where the cells are located within the placenta and their cell morphology and phenotype. We also propose nomenclature for the cell populations and derivatives discussed herein. This review is a joint effort from the COST SPRINT Action (CA17116), which broadly aims at approaching consensus for different aspects of PnD research, such as providing inputs for future standards for the processing and in vitro characterization and clinical application of PnD.

Characterization of the interaction between human decidua parietalis mesenchymal stem/stromal cells and natural killer cells

Background

Human decidua parietalis mesenchymal stem/multipotent stromal cells (DPMSCs) have unique phenotypic and functional properties that make them promising candidates for cell-based therapy. Here, we investigated DPMSC interaction with natural killer (NK) cells, and the effects of this interaction on NK cell phenotypic characteristics and functional activities.

Methods

DPMSCs isolated from the decidua parietalis of human fetal membranes were cultured with interleukin (IL)-2-activated and IL-2-unactivated NK cells isolated from healthy human peripheral blood. NK cell proliferation and cytolytic activities were then examined using functional assays. NK cell expression of receptors mediating the cytolytic activity against DPMSCs, and the mechanism underlying this effect on DPMSCs, were also examined using flow cytometry and light microscopy, respectively.

Results

DPMSCs stimulated IL-2-induced proliferation of resting NK cells and the proliferation of activated NK cells. Moreover, IL-2-activated NK cells, but not freshly isolated NK cells, efficiently lysed DPMSCs. The induction of this NK cell cytolytic activity against DPMSCs was mediated by the activating NK cell receptors NKG2D, CD69, NKp30, and NKp44. However, DPMSCs showed a direct induction of NK cell cytolytic activity through CD69. We also found that DPMSCs expressed the ligands for these activating NK cell receptors including Nectin-2, ULBP-2, MICA, and MICB. Although DPMSCs expressed HLA class I molecules, they were susceptible to lysis by NK cells, suggesting that HLA class I antigens do not play a significant role in NK cell cytolytic action. In addition, DPMSCs did not inhibit NK cell cytolytic activity against cancer cells. Importantly, DPMSCs significantly increased NK expression of inflammatory molecules with anticancer activities.

Conclusions

We conclude that DPMSCs have potential for therapeutic application in cancer therapy, but not in transplantation or immunological diseases.

Comparison of the Biological Characteristics of Mesenchymal Stem Cells Derived from the Human Placenta and Umbilical Cord

Mesenchymal stem/stromal cells (MSCs) derived from placental tissue show great therapeutic potential and have been used in medical treatment, but the similarity and differences between the MSCs derived from various parts of the placenta remain unclear. In this study, we compared MSCs derived from different perinatal tissues, including the umbilical cord (UC), amniotic membrane (AM), chorionic plate (CP) and decidua parietalis (DP). Using human leukocyte antigen (HLA) typing and karyotype analysis, we found that the first three cell types were derived from the foetus, while the MSCs from the decidua parietalis were derived from the maternal portion of the placental tissue. Our results indicate that both foetal and maternal MSCs share a similar phenotype and multi-lineage differentiation potential, but foetal MSCs show a significantly higher expansion capacity than do maternal MSCs. Furthermore, MSCs from all sources showed significant differences in the levels of several paracrine factors.

Choriodecidual leukocytes display a unique gene expression signature in spontaneous labor at term

Prior to and during the process of human labor, maternal circulating leukocytes infiltrate the maternal-fetal interface (choriodecidua) and become activated resembling choriodecidual leukocytes. Since, there is no evidence comparing maternal circulating and choriodecidual leukocytes, herein, we characterized their transcriptome and explored the biological processes enriched in choriodecidual leukocytes. From women undergoing spontaneous term labor we isolated circulating and choriodecidual leukocytes, performed microarray analysis (n = 5) and qRT-PCR validation (n = 9) and interaction network analysis with up-regulated genes. We found 270 genes up-regulated and only 17 genes down-regulated in choriodecidual leukocytes compared to maternal circulating leukocytes. The most up-regulated genes were CCL18, GPNMB, SEPP1, FN1, RNASE1, SPP1, C1QC, and PLTP. The biological processes enriched in choriodecidual leukocytes were cell migration and regulation of immune response, chemotaxis, and humoral immune responses. Our results show striking differences between the transcriptome of choriodecidual and maternal circulating leukocytes. Choriodecidual leukocytes are enriched in immune mediators implicated in the spontaneous process of labor at term.

Isolation and Characterization of Mesenchymal Stem/Stromal Cells Derived from Human Third Trimester Placental Chorionic Villi and Decidua Basalis

The decidua basalis and placental chorionic villi are critical components of maternal-fetal interface, which plays a critical role in normal placental development. Failure to form a proper maternal-fetal interface is associated with clinically important placental pathologies including preeclampsia and fetal growth restriction. Placental trophoblast cells are well known for their critical roles in establishing the maternal-fetal interface; however accumulating evidence also implicates mesenchymal stem/stromal cells that envelop the maternal and fetal blood vessels as playing an important role in the formation and efficient functioning of the interface. Moreover, recent studies associate abnormal mesenchymal stem/stromal cell function in the development of preeclampsia. Further research is needed to fully understand the role that these cells play in this clinically important placental pathology.The intimate relationship between maternal and fetal tissues at the interface poses significant problems in the enrichment of decidua basalis and chorionic villous mesenchymal stem/stromal cells without significant cross-contamination. The protocols described below for the enrichment and characterization of mesenchymal stem/stromal cells from the maternal-fetal interface produce highly enriched cells that conform to international standards and show minimal cross-contamination.

Mesenchymal stromal/stem cell separation methods: concise review

Mesenchymal stem (stromal) cells (MSCs) possess unique biological characteristics such as plasticity, long term self-renewal, secretion of various bioactive molecules and ability of active migration to the diseased tissues that make them unique tool for regenerative medicine, nowadays. Until now MSCs were successfully derived from many tissue sources including bone marrow, umbilical cord, adipose tissue, dental pulp etc. The crucial step prior to their in vitro expansion, banking or potential clinical application is their separation. This review article aims to briefly describe the main MSCs separations techniques currently available, their basic principles, as well as their advantages and limits. In addition the attention is paid to the markers presently applicable for immunoaffinity-based separation of MSCs from different tissues and organs.

The application of decellularized human term fetal membranes in tissue engineering and regenerative medicine (TERM)

Tissue engineering and regenerative medicine (TERM) is a field that applies biology and engineering principles to "restore, maintain or repair a tissue after injury". Besides the potential to treat various diseases, these endeavours increase our understanding of fundamental cell biology. Although TERM has progressed rapidly, engineering a whole organ is still beyond our skills, primarily due to the complexity of tissues. Material science and current manufacturing methods are not capable of mimicking this complexity. Therefore, many researchers explore the use of naturally derived materials that maintain important biochemical, structural and mechanical properties of tissues. Consequently, employing non-cellular components of tissues, particularly the extracellular matrix, has emerged as an alternative to synthetic materials. Because of their complexity, decellularized tissues are not as well defined as synthetic materials but they provide cells with a microenvironment that resembles their natural niche. Decellularized tissues are produced from a variety of sources, among which the fetal membranes are excellent candidates since their supply is virtually unlimited, they are readily accessible with minimum ethical concerns and are often discarded as a biological waste. In this review, we will discuss various applications of decellularized fetal membranes as substrates for the expansion of stem cells, their use as two and three-dimensional scaffolds for tissue regeneration, and their use as cell delivery systems. We conclude that fetal membranes have great potential for use in TERM.

Avoidance of Maternal Cell Contamination and Overgrowth in Isolating Fetal Chorionic Villi Mesenchymal Stem Cells from Human Term Placenta

Human placenta is rich in mesenchymal stem/stromal cells (MSC), with their origin widely presumed fetal. Cultured placental MSCs are confounded by a high frequency of maternal cell contamination. Our recent systematic review concluded that only a small minority of placental MSC publications report fetal/maternal origin, and failed to discern a specific methodology for isolation of fetal MSC from term villi. We determined isolation conditions to yield fetal and separately maternal MSC during ex vivo expansion from human term placenta. MSCs were isolated via a range of methods in combination; selection from various chorionic regions, different commercial media, mononuclear cell digest and/or explant culture. Fetal and maternal cell identities were quantitated in gender‐discordant pregnancies by XY chromosome fluorescence in situ hybridization. We first demonstrated reproducible maternal cell contamination in MSC cultures from all chorionic anatomical locations tested. Cultures in standard media rapidly became composed entirely of maternal cells despite isolation from fetal villi. To isolate pure fetal cells, we validated a novel isolation procedure comprising focal dissection from the cotyledonary core, collagenase/dispase digestion and explant culture in endothelial growth media that selected, and provided a proliferative environment, for fetal MSC. Comparison of MSC populations within the same placenta confirmed fetal to be smaller, more osteogenic and proliferative than maternal MSC. We conclude that in standard media, fetal chorionic villi‐derived MSC (CV‐MSC) do not grow readily, whereas maternal MSC proliferate to result in maternal overgrowth during culture. Instead, fetal CV‐MSCs require isolation under specific conditions, which has implications for clinical trials using placental MSC. Stem Cells Translational Medicine2017;6:1070–1084

Decellularized extracellular matrices produced from immortal cell lines derived from different parts of the placenta support primary mesenchymal stem cell expansion

Mesenchymal stem/stromal cells (MSCs) exhibit undesired phenotypic changes during ex vivo expansion, limiting production of the large quantities of high quality primary MSCs needed for both basic research and cell therapies. Primary MSCs retain many desired MSC properties including proliferative capacity and differentiation potential when expanded on decellularized extracellular matrix (dECM) prepared from primary MSCs. However, the need to use low passage number primary MSCs (passage 3 or lower) to produce the dECM drastically limits the utility and impact of this technology. Here, we report that primary MSCs expanded on dECM prepared from high passage number (passage 25) human telomerase reverse transcriptase (hTERT) transduced immortal MSC cell lines also exhibit increased proliferation and osteogenic differentiation. Two hTERT-transduced placenta-derived MSC cell lines, CMSC29 and DMSC23 [derived from placental chorionic villi (CMSCs) and decidua basalis (DMSCs), respectively], were used to prepare dECM-coated substrates. These dECM substrates showed structural and biochemical differences. Primary DMSCs cultured on dECM-DMSC23 showed a three-fold increase in cell number after 14 days expansion in culture and increased osteogenic differentiation compared with controls. Primary CMSCs cultured on the dECM-DMSC23 exhibited a two-fold increase in cell number and increased osteogenic differentiation. We conclude that immortal MSC cell lines derived from different parts of the placenta produce dECM with varying abilities for supporting increased primary MSC expansion while maintaining important primary MSC properties. Additionally, this is the first demonstration of using high passage number cells to produce dECM that can promote primary MSC expansion, and this advancement greatly increases the feasibility and applicability of dECM-based technologies.

Phenotypic and Functional Characterization of Mesenchymal Stem/Multipotent Stromal Cells From Decidua Parietalis of Human Term Placenta

Mesenchymal stem/multipotent stromal cells (MSCs) from the human placenta show stem cell-like properties useful for regenerative medicine. Previously, we reported that MSCs isolated from the fetal part of human term placentae have characteristics, which make them a potential candidate for regenerative medicine. In this study, we characterized MSC isolated from the maternal part of human term placenta. The MSCs were isolated from the decidua parietalis (DPMSCs) of human placenta using a digestion method and characterized by colony-forming unit assay and the expression of MSC markers by flow cytometry technique. In addition, DPMSC differentiation into the 3 mesenchymal lineages was also performed. Moreover, the gene and protein expression profiles of DPMSCs were identified by real-time polymerase chain reaction and flow cytometry techniques, respectively. Furthermore, proteins secreted by DPMSCs were detected by sandwich enzyme-linked immunosorbent assays. Finally, the proliferation and migration potentials of DPMSCs were also determined. The DPMSCs were positive for MSC markers and negative for hematopoietic and endothelial markers, as well as costimulatory molecules and HLA-DR. Functionally, DPMSCs formed colonies and differentiated into chondrocytes, osteocytes, and adipocytes. In addition, they proliferated and migrated in response to different stimuli. Finally, they expressed and secreted many biological and immunological factors with multiple functions. Here, we carry out an extensive characterization of DPMSCs of human placenta. We report that these cells express and secrete a wide range of molecules with multiple functions, and therefore, we suggest that these cells could be an attractive candidate for cell-based therapy.

Endometrial stem/progenitor cells: the first 10 years

BACKGROUND

The existence of stem/progenitor cells in the endometrium was postulated many years ago, but the first functional evidence was only published in 2004. The identification of rare epithelial and stromal populations of clonogenic cells in human endometrium has opened an active area of research on endometrial stem/progenitor cells in the subsequent 10 years.

METHODS

The published literature was searched using the PubMed database with the search terms ‘endometrial stem cells and menstrual blood stem cells' until December 2014.

RESULTS

Endometrial epithelial stem/progenitor cells have been identified as clonogenic cells in human and as label-retaining or CD44⁺ cells in mouse endometrium, but their characterization has been modest. In contrast, endometrial mesenchymal stem/stromal cells (MSCs) have been well characterized and show similar properties to bone marrow MSCs. Specific markers for their enrichment have been identified, CD146⁺PDGFRβ⁺ (platelet-derived growth factor receptor beta) and SUSD2⁺ (sushi domain containing-2), which detected their perivascular location and likely pericyte identity in endometrial basalis and functionalis vessels. Transcriptomics and secretomics of SUSD2⁺ cells confirm their perivascular phenotype. Stromal fibroblasts cultured from endometrial tissue or menstrual blood also have some MSC characteristics and demonstrate broad multilineage differentiation potential for mesodermal, endodermal and ectodermal lineages, indicating their plasticity. Side population (SP) cells are a mixed population, although predominantly vascular cells, which exhibit adult stem cell properties, including tissue reconstitution. There is some evidence that bone marrow cells contribute a small population of endometrial epithelial and stromal cells. The discovery of specific markers for endometrial stem/progenitor cells has enabled the examination of their role in endometrial proliferative disorders, including endometriosis, adenomyosis and Asherman's syndrome. Endometrial MSCs (eMSCs) and menstrual blood stromal fibroblasts are an attractive source of MSCs for regenerative medicine because of their relative ease of acquisition with minimal morbidity. Their homologous and non-homologous use as autologous and allogeneic cells for therapeutic purposes is currently being assessed in preclinical animal models of pelvic organ prolapse and phase I/II clinical trials for cardiac failure. eMSCs and stromal fibroblasts also exhibit non-stem cell-associated immunomodulatory and anti-inflammatory properties, further emphasizing their desirable properties for cell-based therapies.

CONCLUSIONS

Much has been learnt about endometrial stem/progenitor cells in the 10 years since their discovery, although several unresolved issues remain. These include rationalizing the terminology and diagnostic characteristics used for distinguishing perivascular stem/progenitor cells from stromal fibroblasts, which also have considerable differentiation potential. The hierarchical relationship between clonogenic epithelial progenitor cells, endometrial and decidual SP cells, CD146⁺PDGFR-β⁺ and SUSD2⁺ cells and menstrual blood stromal fibroblasts still needs to be resolved. Developing more genetic animal models for investigating the role of endometrial stem/progenitor cells in endometrial disorders is required, as well as elucidating which bone marrow cells contribute to endometrial tissue. Deep sequencing and epigenetic profiling of enriched populations of endometrial stem/progenitor cells and their differentiated progeny at the population and single-cell level will shed new light on the regulation and function of endometrial stem/progenitor cells.

Ectopic Bone Formation by Mesenchymal Stem Cells Derived from Human Term Placenta and the Decidua

Mesenchymal stem cells (MSCs) are one of the most attractive cell types for cell-based bone tissue repair applications. Fetal-derived MSCs and maternal-derived MSCs have been isolated from chorionic villi of human term placenta and the decidua basalis attached to the placenta following delivery, respectively. Chorionic-derived MSCs (CMSCs) and decidua-derived MSCs (DMSCs) generated in this study met the MSCs criteria set by International Society of Cellular Therapy. These criteria include: (i) adherence to plastic; (ii) >90% expression of CD73, CD105, CD90, CD146, CD44 and CD166 combined with <5% expression of CD45, CD19 and HLA-DR; and (iii) ability to differentiate into osteogenic, adipogenic, and chondrogenic lineages. In vivo subcutaneous implantation into SCID mice showed that both bromo-deoxyuridine (BrdU)-labelled CMSCs and DMSCs when implanted together with hydroxyapatite/tricalcium phosphate particles were capable of forming ectopic bone at 8-weeks post-transplantation. Histological assessment showed expression of bone markers, osteopontin (OPN), osteocalcin (OCN), biglycan (BGN), bone sialoprotein (BSP), and also a marker of vasculature, alpha-smooth muscle actin (α-SMA). This study provides evidence to support CMSCs and DMSCs as cellular candidates with potent bone forming capacity.

Human mesenchymal stem cells - current trends and future prospective

Stem cells are cells specialized cell, capable of renewing themselves through cell division and can differentiate into multi-lineage cells. These cells are categorized as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs) and adult stem cells. Mesenchymal stem cells (MSCs) are adult stem cells which can be isolated from human and animal sources. Human MSCs (hMSCs) are the non-haematopoietic, multipotent stem cells with the capacity to differentiate into mesodermal lineage such as osteocytes, adipocytes and chondrocytes as well ectodermal (neurocytes) and endodermal lineages (hepatocytes). MSCs express cell surface markers like cluster of differentiation (CD)29, CD44, CD73, CD90, CD105 and lack the expression of CD14, CD34, CD45 and HLA (human leucocyte antigen)-DR. hMSCs for the first time were reported in the bone marrow and till now they have been isolated from various tissues, including adipose tissue, amniotic fluid, endometrium, dental tissues, umbilical cord and Wharton's jelly which harbours potential MSCs. hMSCs have been cultured long-term in specific media without any severe abnormalities. Furthermore, MSCs have immunomodulatory features, secrete cytokines and immune-receptors which regulate the microenvironment in the host tissue. Multilineage potential, immunomodulation and secretion of anti-inflammatory molecules makes MSCs an effective tool in the treatment of chronic diseases. In the present review, we have highlighted recent research findings in the area of hMSCs sources, expression of cell surface markers, long-term in vitro culturing, in vitro differentiation potential, immunomodulatory features, its homing capacity, banking and cryopreservation, its application in the treatment of chronic diseases and its use in clinical trials.

Concise review: the surface markers and identity of human mesenchymal stem cells

The concept of mesenchymal stem cells (MSCs) is becoming increasingly obscure due to the recent findings of heterogeneous populations with different levels of stemness within MSCs isolated by traditional plastic adherence. MSCs were originally identified in bone marrow and later detected in many other tissues. Currently, no cloning based on single surface marker is capable of isolating cells that satisfy the minimal criteria of MSCs from various tissue environments. Markers that associate with the stemness of MSCs await to be elucidated. A number of candidate MSC surface markers or markers possibly related to their stemness have been brought forward so far, including Stro-1, SSEA-4, CD271, and CD146, yet there is a large difference in their expression in various sources of MSCs. The exact identity of MSCs in vivo is not yet clear, although reports have suggested they may have a fibroblastic or pericytic origin. In this review, we revisit the reported expression of surface molecules in MSCs from various sources, aiming to assess their potential as MSC markers and define the critical panel for future investigation. We also discuss the relationship of MSCs to fibroblasts and pericytes in an attempt to shed light on their identity in vivo.

High incidence of contaminating maternal cell overgrowth in human placental mesenchymal stem/stromal cell cultures: a systematic review

Placenta is a readily accessible translationally advantageous source of mesenchymal stem/stromal cells (MSCs) currently used in cryobanking and clinical trials. MSCs cultured from human chorion have been widely assumed to be fetal in origin, despite evidence that placental MSCs may be contaminated with maternal cells, resulting in entirely maternally derived MSC cultures. To document the frequency and determinants of maternal cell contamination in chorionic MSCs, we undertook a PRISMA-compliant systematic review of publications in the PubMed, Medline, and Embase databases (January 2000 to July 2013) on placental and/or chorionic MSCs from uncomplicated pregnancies. Of 147 studies, only 26 (18%) investigated fetal and/or maternal cell origin. After excluding studies that did not satisfy minimal MSC criteria, 7 of 15 informative studies documented MSC cultures as entirely fetal, a further 7 studies reported cultured human chorionic MSC populations to be either maternal (n=6) or mixed (n=1), whereas 1 study separately cultured pure fetal and pure maternal MSC from the same placenta. Maternal cell contamination was associated with term and chorionic membrane samples and greater passage number but was still present in 30% of studies of chorionic villous MSCs. Although most studies assume fetal origin for MSCs sourced from chorion, this systematic review documents a high incidence of maternal-origin MSC populations in placental MSC cultures. Given that fetal MSCs have more primitive properties than adult MSCs, our findings have implications for clinical trials in which knowledge of donor and tissue source is pivotal. We recommend sensitive methods to quantitate the source and purity of placental MSCs.

Differential expression of microRNAs in decidua-derived mesenchymal stem cells from patients with pre-eclampsia

BACKGROUND

Mesenchymal stem cells (MSCs) at maternal-fetal interface are considered to play an important role in the pathogenesis of pre-eclampsia (PE). microRNAs (miRNAs) also have an important influence on differentiation, maturation, and functions of MSCs. Our aim in this study was to determine the differential expression of miRNAs in decidua-derived MSCs (dMSCs) from severe PE and normal pregnancies.

RESULTS

miRNA expression profiles in dMSCs from five patients with severe PE and five healthy pregnant women were screened using microarray. Then, bioinformatic analysis of the microarray results was performed. Out of 179 differentially expressed miRNAs, 49 miRNAs had significant (p < 0.05) differential expression of ≥ 2.0-fold changes, including 21 up-regulated and 28 down-regulated. miRNA-Gene-network and miRNA-Gene ontology (GO) -network analyses were performed. Overall, 21 up-regulated and 15 down-regulated miRNAs showed high degrees in these analyses. Moreover, the significantly enriched signaling pathways and GOs were identified. The analyses revealed that pathways associated with cell proliferation, angiogenesis, and immune functions were highly regulated by the differentially expressed miRNAs, including Wnt signaling pathway, mitogen-activated protein kinase signaling pathway, transforming growth factor beta signaling pathway, T-cell receptor signaling pathway, and B cell receptor signaling pathway. Four miRNA predicted target genes, vascular endothelial growth factor A (VEGFA), indoleamine 2,3-dioxygenase, suppression of cytokine signaling 3, and serine/threonine protein phosphatase 2A 55 kDa regulatory subunit B α isoform (PPP2R2A) were all decreased in dMSCs from patients with PE. Furthermore, the physiological roles of miR-16 and miR-136 in the down-regulation of VEGFA and PPP2R2A, respectively, were confirmed through reporter assays.

CONCLUSIONS

These findings suggest that miRNAs in dMSCs may be important regulatory molecules in the development of PE.

A novel combination of homeobox genes is expressed in mesenchymal chorionic stem/stromal cells in first trimester and term pregnancies

Human chorionic mesenchymal stem/stromal cells (CMSCs) derived from the placenta are similar to adult tissue-derived MSCs. The aim of this study was to investigate the role of these cells in normal placental development. Transcription factors, particularly members of the homeobox gene family, play crucial roles in maintaining stem cell proliferation and lineage specification in embryonic tissues. In adult tissues and organs, stem cells proliferate at low levels in their niche until they receive cues from the microenvironment to differentiate. The homeobox genes that are expressed in the CMSC niche in placental tissues have not been identified. We used the novel strategy of laser capture microdissection to isolate the stromal component of first trimester villi and excluded the cytotrophoblast and syncytiotrophoblast layers that comprise the outer layer of the chorionic villi. Microarray analysis was then used to screen for homeobox genes in the microdissected tissue. Candidate homeobox genes were selected for further RNA analysis. Immunohistochemistry of candidate genes in first trimester placental villous stromal tissue revealed homeobox genes Meis1, myeloid ectropic viral integration site 1 homolog 2 (MEIS2), H2.0-like Drosophila (HLX), transforming growth factor β-induced factor (TGIF), and distal-less homeobox 5 (DLX5) were expressed in the vascular niche where CMSCs have been shown to reside. Expression of MEIS2, HLX, TGIF, and DLX5 was also detected in scattered stromal cells. Real-time polymerase chain reaction and immunocytochemistry verified expression of MEIS2, HLX, TGIF, and DLX5 homeobox genes in first trimester and term CMSCs. These data suggest a combination of regulatory homeobox genes is expressed in CMSCs from early placental development to term, which may be required for stem cell proliferation and differentiation.

Mesenchymal-to-endothelial transition in Kaposi sarcoma: a histogenetic hypothesis based on a case series and literature review

OBJECTIVES

Although several studies have been conducted regarding Kaposi sarcoma (KS), its histogenesis still remains to be elucidated. The aim of our study was to analyze the immunophenotype of Kaposi sarcoma and to present a hypothesis about the histogenesis of this tumor, based on a case series and a review of relevant literature.

METHODS

In 15 cases of KSs diagnosed during 2000-2011, the clinicopathological features were correlated with the immunoexpression of c-Kit, SMA, CD34, CD31, vascular endothelial growth factor (VEGF), COX-2, c-KIT, smooth muscle antigen (SMA), and stem cell surface marker CD105.

RESULTS

Both CD105 and c-KIT rate of the spindle-shaped tumor cell positivity increased in parallel to the pathological stage. All cases displayed CD105 and weak c-KIT positivity in the endothelial cells. SMA, VEGF, and COX-2 were focally expressed in all cases. CD34 marked both endothelium and spindle-shaped tumor cells. No c-KIT expression was noticed in KS of the internal organs.

CONCLUSIONS

KS seems to be a variant of myofibroblastic tumors that originates from the viral modified pluripotent mesenchymal cells of the connective tissue transformed in spindle-shaped KS cells, followed by a mesenchymal-endothelial transition and a myofibroblastic-like differentiation. This paper mailnly showed that KS cannot be considered a pure vascular tumor.

Evidence for a role for the adaptive immune response in human term parturition

PROBLEM

Spontaneous labor at term involves leukocyte recruitment and infiltration into the choriodecidua; yet, characterization of these leukocytes and their immunological mediators is incomplete. The purpose of this study was to characterize the immunophenotype of choriodecidual leukocytes as well as the expression of inflammatory mediators in human spontaneous parturition at term.

METHOD OF STUDY

Choriodecidual leukocytes were analyzed by FACS, immunohistochemistry, and RT-PCR in three different groups: (i) preterm gestation delivered for medical indications without labor; (ii) term pregnancy without labor; and (iii) term pregnancy after spontaneous labor.

RESULTS

Two T-cell subsets of memory-like T cells (CD3(+) CD4(+) CD45RO(+) and CD3(+) CD4(-) CD8(-) CD45RO(+) cells) were identified in the choriodecidua of women who had spontaneous labor. Evidence for an extensive immune signaling network composed of chemokines (CXCL8 and CXCL10), chemokine receptors (CXCR1-3), cytokines (IL-1β and TNF-α), cell adhesion molecules, and MMP-9 was identified in these cells during spontaneous labor at term.

CONCLUSIONS

The influx of memory-like T cells in the choriodecidua and the evidence that they are active by producing chemokines and cytokines, and expressing chemokine receptors, cell adhesion molecules, and a matrix-degrading enzyme provides support for the participation of the adaptive immune system in the mechanisms of spontaneous parturition at term.