Wnt Secretion from Epithelial Cells and Subepithelial Myofibroblasts Is Not Required in the Mouse Intestinal Stem Cell Niche In Vivo

Intestinal stem cells are located at the base of the crypts and are surrounded by a complex structure called niche. This environment is composed mainly of epithelial cells and stroma which provides signals that govern cell maintenance, proliferation, and differentiation. Understanding how the niche regulates stem cell fate by controlling developmental signaling pathways will help us to define how stem cells choose between self-renewal and differentiation and how they maintain their undifferentiated state. Tractable in vitro assay systems, which reflect the complexity of the in vivo situation but provide higher level of control, would likely be crucial in identifying new players and mechanisms controlling stem cell function. Knowledge of the intestinal stem cell niche gathered from both in vivo and novel in vitro models may help us improve therapies for tumorigenesis and intestinal damage and make autologous intestinal transplants a feasible clinical practice.

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PDGFRα+ pericryptal stromal cells are the critical source of Wnts and RSPO3 for murine intestinal stem cells in vivo

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1713510115 ◽

2018 ◽

Vol 115 (14) ◽

pp. E3173-E3181 ◽

Cited By ~ 84

Author(s):

Gediminas Greicius ◽

Zahra Kabiri ◽

Kristmundur Sigmundsson ◽

Chao Liang ◽

Ralph Bunte ◽

...

Keyword(s):

Stem Cell ◽

Stem Cell Niche ◽

Ex Vivo ◽

Paneth Cell ◽

Intestinal Stem Cells ◽

Intestinal Stem Cell ◽

Intestinal Crypt ◽

Proliferation And Differentiation ◽

Cell Niche

Wnts and R-spondins (RSPOs) support intestinal homeostasis by regulating crypt cell proliferation and differentiation. Ex vivo, Wnts secreted by Paneth cells in organoids can regulate the proliferation and differentiation of Lgr5-expressing intestinal stem cells. However, in vivo, Paneth cell and indeed all epithelial Wnt production is completely dispensable, and the cellular source of Wnts and RSPOs that maintain the intestinal stem-cell niche is not known. Here we investigated both the source and the functional role of stromal Wnts and RSPO3 in regulation of intestinal homeostasis. RSPO3 is highly expressed in pericryptal myofibroblasts in the lamina propria and is several orders of magnitude more potent than RSPO1 in stimulating both Wnt/β-catenin signaling and organoid growth. Stromal Rspo3 ablation ex vivo resulted in markedly decreased organoid growth that was rescued by exogenous RSPO3 protein. Pdgf receptor alpha (PdgfRα) is known to be expressed in pericryptal myofibroblasts. We therefore evaluated if PdgfRα identified the key stromal niche cells. In vivo, Porcn excision in PdgfRα+ cells blocked intestinal crypt formation, demonstrating that Wnt production in the stroma is both necessary and sufficient to support the intestinal stem-cell niche. Mice with Rspo3 excision in the PdgfRα+ cells had decreased intestinal crypt Wnt/β-catenin signaling and Paneth cell differentiation and were hypersensitive when stressed with dextran sodium sulfate. The data support a model of the intestinal stem-cell niche regulated by both Wnts and RSPO3 supplied predominantly by stromal pericryptal myofibroblasts marked by PdgfRα.

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Reconstitution of intestinal stem cell niche in vitro with pharmacological inhibitors or L-WRN conditioned medium differentially regulates epithelial proliferation, differentiation and barrier function in rabbit caecum organoids

10.1101/2020.04.02.021550 ◽

2020 ◽

Author(s):

Eloïse Mussard ◽

Cécile Pouzet ◽

Virginie Helies ◽

Géraldine Pascal ◽

Sandra Fourre ◽

...

Keyword(s):

Gene Expression ◽

Stem Cells ◽

Stem Cell ◽

Epithelial Cells ◽

Conditioned Medium ◽

Barrier Function ◽

Stem Cell Niche ◽

Intestinal Stem Cell ◽

Cell Niche

AbstractIntestinal organoids are self-organized 3-dimensional (3D) structures formed by a single layer of polarized epithelial cells. This innovative in vitro model is highly relevant to study physiology of the intestinal epithelium and its role in nutrition and barrier function. However, this model has never been developed in rabbits, while it would have potential applications for biomedical and veterinary research. Here, we cultured rabbit caecum organoids with either pharmacological inhibitors (2Ki medium) or L-WRN cells conditioned medium (L-WRN CM) to reconstitute the intestinal stem cell niche in vitro. Large spherical organoids were obtained with the 2Ki medium and this morphology was associated with a high level of proliferation and stem cells markers gene expression. In contrast, organoids cultured with L-WRN CM had a smaller diameter; a greater cell height and part of them were not spherical. When the L-WRN CM was used at low concentration (5%) for two days, the gene expression of stem cells and proliferation markers were very low, while absorptive and secretory cells markers and antimicrobial peptides were elevated. Epithelial cells within organoids were polarized in 3D cultures with 2Ki medium or L-WRN CM (apical side towards the lumen). We cultured dissociated organoid cells in 2D monolayers, which allowed accessibility to the apical compartment. Under these conditions, actin stress fibers were observed with the 2Ki medium, while perijonctionnal localization of actin was observed with the L-WRN CM suggesting, in 2D cultures as well, a higher differentiation level in the presence of L-WRN CM. In conclusion, rabbit caecum organoids cultured with the 2Ki medium were more proliferative and less differentiated than organoids cultured with L-WRN CM. We propose that organoids cultured with the 2Ki medium could be used to rapidly generate in vitro a large number of rabbit intestinal epithelial stem cells while organoids cultured with the L-WRN CM represent a suitable model to study differentiated rabbit epithelium.

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Faculty Opinions recommendation of Visualization of a short-range Wnt gradient in the intestinal stem-cell niche.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726134575.793554531 ◽

2018 ◽

Author(s):

Mirna Perez-Moreno

Keyword(s):

Stem Cell ◽

Stem Cell Niche ◽

Short Range ◽

Intestinal Stem Cell ◽

Cell Niche

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MESENCHYMAL TNFR1 EXPRESSION PRESERVES THE COLONIC EPITHELIAL STEM CELL NICHE

Inflammatory Bowel Diseases ◽

10.1093/ibd/izaa347.018 ◽

2021 ◽

Vol 27 (Supplement_1) ◽

pp. S7-S8

Author(s):

Safina Gadeock ◽

Cambrian Liu ◽

Brent Polk

Keyword(s):

Stem Cell ◽

Stem Cell Niche ◽

Mesenchymal Cells ◽

Epithelial Stem Cells ◽

Epithelial Stem Cell ◽

Long Term Treatment ◽

Lgr5 Expression ◽

Cell Niche

Abstract Tumor necrosis factor (TNF) is a highly expressed cytokine in inflammatory bowel disease (IBD). Although TNF can induce colonic epithelial dysfunction and apoptosis, recent studies suggest that TNF signalling promotes epithelial wound repair and stem cell function. Here we investigated the role of TNF receptor 1 (TNFR1) in mediating TNF’s effects on colonic epithelial stem cells, integral to mucosal healing in colitis. We demonstrate that Tnfr1-/- mice exhibit loss in Lgr5 expression (-52%, p<0.02; N=6) compared to wildtype (WT) controls. However, the opposite result was found in vitro, wherein murine Tnfr1-/- colonoids demonstrated a significant increase in Lgr5 expression (66%, p<0.007; N=6) compared to WT colonoids. Similarly, human colonoids treated with an anti-TNFR1 antibody also demonstrated an increase in Lgr5 expression, relative to IgG controls. To resolve the contradiction in the in vivo versus in vitro environment, we hypothesized that mesenchymal TNFR1 expression regulates the epithelial stem cell niche. To determine the relationships between these cell types, we co-cultured WT or Tnfr1-/- colonoids with WT or Tnfr1-/- colonic myofibroblasts (CMFs). We found that epithelial Lgr5 expression was significantly higher (by 52%, p<0.05; N=3) when co-cultured with WT compared to TNFR1-/- myofibroblasts. The loss of TNFR1 expression in vivo increases the number of αSMA+ mesenchymal cells by nearly 56% (N=6) but considerably reduces the pericryptal PDGFRα+ cells, suggesting modifications in mesenchymal populations that contribute to the epithelial stem cell niche. Functionally, primary Tnfr1-/--CMFs displayed PI3k (p<0.001; N=3) and MAPK (p<0.01; N=3)-dependent increases in migration, proliferation, and differentiation, but RNA profiling demonstrated by diminished levels of stem cell niche factors, Rspo3 (-80%, p<0.0001; N=6) and Wnt2b (-63%, p<0.008; N=6) compared to WT-CMFs. Supplementation with 50ng recombinant Rspo3 for 5 d to Lgr5-GFP organoids co-cultured with TNFR1-/--CMFs restored Lgr5 expression to wildtype levels. Therefore, TNFR1-mediated TNF signalling in mesenchymal cells promotes their ability to support an epithelial stem cell niche. These results should motivate future studies of the stem cell niche in the context of long-term treatment with anti-TNF therapies.

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