Project description:Bone marrow (BM) stromal cells are important in the development and maintenance of cells of the immune system. Using single cell RNA sequencing, we here explore the functional and phenotypic heterogeneity of individual transcriptomes of 1,167 murine BM mesenchymal stromal cells. These cells exhibit a tremendous heterogeneity of gene expression, which precludes the identification of defined subpopulations. However, according to the expression of 108 genes involved in the communication of stromal cells with hematopoietic cells, we have identified 14 non-overlapping subpopulations, with distinct cytokine or chemokine gene expression signatures. With respect to the maintenance of subsets of immune memory cells by stromal cells, we identify distinct subpopulations expressing IL7, IL15 and Tnfsf13b. Together, this study provides a comprehensive dissection of the BM stromal heterogeneity at the single cell transcriptome level and provides a basis to understand their lifestyle and their role as organizers of niches for the long-term maintenance of immune cells.
Project description:Bone marrow (BM) stromal cells are important in the development and maintenance of cells of the immune system. Using single cell RNA sequencing, we here explore the functional and phenotypic heterogeneity of individual transcriptomes of 1167 murine BM mesenchymal stromal cells. These cells exhibit a tremendous heterogeneity of gene expression, which precludes the identification of defined subpopulations. However, according to the expression of 108 genes involved in the communication of stromal cells with hematopoietic cells, we have identified 14 non-overlapping subpopulations, with distinct cytokine or chemokine gene expression signatures. With respect to the maintenance of subsets of immune memory cells by stromal cells, we identified distinct subpopulations expressing Il7, Il15 and Tnfsf13b. Together, this study provides a comprehensive dissection of the BM stromal heterogeneity at the single cell transcriptome level and provides a basis to understand their lifestyle and their role as organizers of niches for the long-term maintenance of immune cells.
Project description:Comprehensive transcriptional characterization of bone marrow stromal cells by RNA sequencing was performed to determine the molecular properties/signatures of endothelium during niche formation.Here, we identify a rare subset of cells in the human fetal BM that co-express endothelial and stromal markers, including low-affinity nerve growth factor receptor (LNGFR/CD271). They display transcriptional reprogramming consistent with endothelial-to-mesenchymal transition (EndoMT), reflected in their potential to generate stromal cells with in vivo BM niche forming capacity.
Project description:Recent studies suggest that bone marrow stromal cells are critical for forming a niche that maintains hematopoietic stem cells’ quiescence and adapt blood production to the organism’s needs. Alterations in the bone marrow niche are commonly observed in blood malignancies and directly contribute to the aberrant function of disease-initiating leukemic stem cells. We used microarrays to detail the global programme of stromal cells' gene expression during leukemic progression.
Project description:Bone marrow (BM) mesenchymal stem/stromal cells are non-hematopoietic (CD45-), non-endothelial (CD31-) multipotential cells capable to differentiate into osteoblastes, chondrocytes and adipocytes. In addition, different subpopulations of MSCs and some of their derivatives (early osteoblastic lineage cells) were shown to form HSC-niche. This makes a complex picture of the relationship between MSCs and HSCs. Despite growing data in mice model, few describe the human counterpart. The BM CD200+ and CD271+ fractions were previously shown to be enriched in native MSCs in human. Herein, we found heterogeneity in expression of CD200 within CD45-/CD31-/CD271+ human BM fraction. We thus selected CD200+ and CD200- cells from CD45-/CD31-/CD271+ BM samples and we analyzed their transcriptome. The differential display of gene expression between these two types of BM fractions will give new insights in the identification of native human MSCs.
Project description:Stromal cells (SCs) establish the compartmentalization of lymphoid tissues critical to the immune response. However, the full diversity of lymph node (LN) SCs remains undefined. Using droplet-based single-cell RNA sequencing we identified 9 peripheral LNs non-endothelial SC subsets. Included are the established subsets Ccl19hi T-zone reticular cells (TRCs), marginal reticular cells, follicular dendritic cells (FDCs) and perivascular cells. We also identified Ccl19lo TRCs, likely including cholesterol-25-hydroxylase+ cells located at the T-zone perimeter, Cxcl9+ TRCs in the T-zone and interfollicular region, CD34+ SCs in the capsule and medullary vessel adventitia, indolethylamine N-methyltransferase+ SCs in the medullary cords and Nr4a1+ SCs in several niches. These data help define how transcriptionally distinct LN SCs support niche-restricted immune functions and they provide evidence that many SCs are in an activated state.
Project description:Characterisation of the extracellular vesicles shed by follicular lymphoma B cells that induce the polarization of bone marrow stroma cell toward a pro-tumoral niche.
Project description:Adult hematopoietic stem cells (HSCs) reside primarily in bone marrow. However, hematopoietic stresses such as myelofibrosis, anemia, pregnancy, infection or myeloablation can mobilize HSCs to the spleen and induce extramedullary hematopoiesis (EMH). While the bone marrow HSC niche has been studied intensively, the EMH niche has received little attention. Here, we systematically assessed the physiological sources of the key niche factors, SCF and CXCL12, in the mouse spleen after EMH induction by cyclophosphamide plus granulocyte colony-stimulating factor, blood loss, or pregnancy. In each case, Scf was expressed by endothelial cells and Tcf21+ stromal cells, primarily around sinusoids in red pulp, while Cxcl12 was expressed by a subset of Tcf21+ stromal cells. EMH induction markedly expanded the Scf-expressing endothelial cells and stromal cells by inducing proliferation. Most splenic HSCs were adjacent to Tcf21+ stromal cells in red pulp. Conditional deletion of Scf from spleen endothelial cells or Scf or Cxcl12 from Tcf21+ stromal cells severely reduced spleen EMH and reduced blood cell counts without affecting bone marrow hematopoiesis. Endothelial cells and Tcf21+ stromal cells thus create the splenic EMH niche, which is necessary for the physiological response to diverse hematopoietic stresses. Unfractionated spleen cells (2 replicates) and FACS-sorted VE-cadherein negative Scf-GFP positive cells (3 replicates)