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Human placental villi contain stromal macrovesicles associated with networks of stellate cells.

ABSTRACT: Placental function is essential for fetal development and establishing the foundations for lifelong health. The placental villous stroma is a connective tissue layer that supports the fetal capillaries and villous trophoblast. All the nutrients that cross the placenta must also cross the stroma, and yet little is known about this region. This study uses high-resolution three-dimensional imaging to explore the structural complexity of this region within the placental villi. Serial block-face scanning electron microscopy and confocal microscopy were used to image the placental villous stroma in three-dimensions. Transmission electron microscopy (TEM) was used to generate high resolution two-dimensional images. Stereological approaches were used to quantify volumes of stromal constituents. Three-dimensional imaging identified stromal extracellular vesicles, which constituted 3.9% of the villous stromal volume. These stromal extracellular vesicles were ovoid in shape, had a median length of 2750 nm (range 350-7730 nm) and TEM imaging confirmed that they were bounded by a lipid bilayer. Fifty-nine per cent of extracellular vesicles were in contact with a fibroblast-like stellate cell and these vesicles were significantly larger than those where no contact was observed. These stellate cells formed local networks with adherent junctions observed at contact points. This study demonstrates that the villous stroma contains extracellular macrovesicles which are considerably larger than any previously described in tissue or plasma. The size and abundance of these macrovesicles in the villous stroma highlight the diversity of extracellular vesicle biology and their roles within connective tissues.

SUBMITTER: Palaiologou E

PROVIDER: S-EPMC6904625 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Human placental villi contain stromal macrovesicles associated with networks of stellate cells.

Palaiologou E E Etter O O Goggin P P Chatelet D S DS Johnston D A DA Lofthouse E M EM Doherty R R Pearson-Farr J J Sengers B G BG Torrens C C Cleal J K JK Page A M AM Lewis R M RM

Journal of anatomy 20190911 1

Placental function is essential for fetal development and establishing the foundations for lifelong health. The placental villous stroma is a connective tissue layer that supports the fetal capillaries and villous trophoblast. All the nutrients that cross the placenta must also cross the stroma, and yet little is known about this region. This study uses high-resolution three-dimensional imaging to explore the structural complexity of this region within the placental villi. Serial block-face scan ...[more]

PMID: 31512233

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Project description:BACKGROUND:Studies in which mesenchymal stromal cells (MSC) from the placenta are compared with multiple MSC types from other sources are rare. The chorionic plate of the human placenta is mainly composed of fetal blood vessels embedded in fetal stroma tissue, lined by trophoblastic cells and organized into chorionic villi (CV) structures. METHODS:We comprehensively characterized human MSC collected from postnatal human chorionic villi of placenta (CV-MSC) by analyzing their growth and proliferation potential, differentiation, immunophenotype, extracellular matrix production, telomere length, aging phenotype, and plasticity. RESULTS:Immunophenotypic characterization of CV-MSC confirmed the typical MSC marker expression as defined by the International Society for Cellular Therapy. The surface marker profile was consistent with increased potential for proliferation, vascular localization, and early myogenic marker expression. CV-MSC retained multilineage differentiation potential and extracellular matrix remodeling properties. They have undergone reduced telomere loss and delayed onset of cellular senescence as they aged in vitro compared to three other MSC sources. We present evidence that increased human telomerase reverse transcriptase gene expression could not explain the exceptional telomere maintenance and senescence onset delay in cultured CV-MSC. Our in-vitro tumorigenesis detection assay suggests that CV-MSC are not prone to undergo malignant transformation during long-term in-vitro culture. Besides SOX2 expression, no other pluripotency features were observed in early and late passages of CV-MSC. CONCLUSIONS:Our work brings forward two remarkable characteristics of CV-MSC, the first being their extended life span as a result of delayed replicative senescence and the second being a delayed aged phenotype characterized by improved telomere length maintenance. MSC from human placenta are very attractive candidates for stem cell-based therapy applications.

Project description:Background & objectivesDuring 6 to 8 wk of gestation, human placental villi show a complex pattern of morphogenesis. There is however, no large scale gene expression study exploring the temporal pattern of the developmental molecular networks in placental villi during the early weeks of gestation. We evaluated the transcriptome profiling of humn placental villus samples obtained from fertile women with voluntarily terminated normal pregnancies between 6-8 wk of gestation.MethodsTranscriptomic profiles of individual human placental villous samples from 25 women with normal pregnancies during 6 to 8 wk of gestation were examined using human whole genome expression arrays. Quantitative RT-PCR validation of copy numbers of transcripts for selected 15 genes and exploratory analysis of the microarray data revealed a high degree of quality assurance supportive of further clustering and differential analyses. Immunoblot and immunohistochemical analysis of selected five candidate proteins (CAGE1, CD9, SLC6A2, TANK and VEGFC) based on transcript profiles were done to assess the pattern of down stream informational flow.ResultsA large number (~9K) of genes with known functions were expressed in the experimental samples. The clustering analysis identified three major expression clusters with gestational age, and four co-expressional clusters. Differential analysis identified a highly discrete regulatory process involving only about 160 genes. Immunochemical analysis of selected candidate proteins based on transcript profiles revealed generally synchronous expression in human early placental villi.Interpretation & conclusionsSeveral signaling pathways linked to immunity (COL1, JAK2, JAK3, IL12, IL13, IL15, IL27, STAT3 and STAT5) were downregulated, while genes of the enriched category of antiviral immunity (ATF/AP1, IL10R and OAS) were clearly over-expressed. Transcriptional integration supportive of programmed development was observed in first trimester placental villi and it included regulation of apoptosis and cell cycle progression (ARRB1, ATR, BLM, CHRNA7, CHRNB1, FYN, KPNA4, and MTOR/FRAP), autophagy (ATG4B, ATG14, BAD, and BCL2), cell adhesion (CD9 and FN1) and epithelial-to-mesenchymal transition (CALD1, FN1, HEY1, MMP2, and WNT3A).

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Human placental villi contain stromal macrovesicles associated with networks of stellate cells.

Publications

Human placental villi contain stromal macrovesicles associated with networks of stellate cells.

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