Project description:Cell cycle quiescence is a critical feature contributing to haematopoietic stem cell (HSC) maintenance. Although various candidate stromal cells have been identified as potential HSC niches, the spatial localization of quiescent HSC in the bone marrow (BM) remains unclear. Here, using a novel approach that combines whole-mount confocal immunofluorescence imaging technique and computational modelling to analyse significant tridimensional associations among vascular structures, stromal cells and HSCs, we show that quiescent HSCs associate specifically with small arterioles that are preferentially found in endosteal BM. These arterioles are ensheathed exclusively by rare Nestin-GFP-peri/NG2+ pericytes, distinct from sinusoid-associated Nestin-GFP-retic/LepR+ cells. The present RNA-seq study sought to obtain a comprehensive understanding of the differences between the two distinct HSC cellular niches. mRNA profiles of sorted Nestin-GFP-peri and -GFP-retic bone marrow stromal cells were generated from pooled mice in triplicate by Illumina HiSeq 2000 sequencing.
Project description:Cell cycle quiescence is a critical feature contributing to haematopoietic stem cell (HSC) maintenance. Although various candidate stromal cells have been identified as potential HSC niches, the spatial localization of quiescent HSC in the bone marrow (BM) remains unclear. Here, using a novel approach that combines whole-mount confocal immunofluorescence imaging technique and computational modelling to analyse significant tridimensional associations among vascular structures, stromal cells and HSCs, we show that quiescent HSCs associate specifically with small arterioles that are preferentially found in endosteal BM. These arterioles are ensheathed exclusively by rare Nestin-GFP-peri/NG2+ pericytes, distinct from sinusoid-associated Nestin-GFP-retic/LepR+ cells. The present RNA-seq study sought to obtain a comprehensive understanding of the differences between the two distinct HSC cellular niches.
Project description:Fate decisions of haematopoietic stem cells (HSCs) to self-renew or differentiate in response to various demands are finely tuned by specialized microenvironments called “niches” in the bone marrow. Recent studies suggest that arterioles and sinusoids accompanied with distinct stromal cells marked by nerve/glial antigen 2 (NG2) and leptin receptor (LepR), compose distinct niches regulating quiescence and proliferation of HSCs, respectively. However, it remains unknown how the distinct niche cells differentially regulate the HSC functions. Here we show that effects of cytokines regulating HSC functions are dependent on the producing cell sources. Deletion of chemokine C-X-C motif ligand 12 (CXCL12) in NG2-cre targeted cells, which exclusively overlap with Nestin-GFP (Nes-GFP)+ stromal cells associated with arterioles and sinusoids, resulted in a robust reductions of HSCs in the bone marrow and massive mobilization. Deletion of CXCL12 from arteriolar NG2+ vascular smooth muscle cells caused a significant decrease of HSCs and altered HSC location in the marrow, while CXCL12 depletion from sinusoidal LepR+ cells did not reduce HSC numbers in the bone marrow. By contrast, deletion of stem cell factor (SCF) in LepR+ cells led to significant reductions in HSC numbers whereas SCF deletion in arteriolar NG2+ cells showed no effect on HSC numbers in the marrow. These results uncover the distinct contributions of cytokines derived from perivascular cells in separate vascular niches for HSC maintenance and mobilization. We sought to obtain comprehensive understanding of differences between peri-arteriolar and peri-sinusoidal niche cells by the present RNA-seq analysis.
Project description:Whereas the cellular basis of the hematopoietic stem cell (HSC) niche in the bone marrow has been characterized, the nature of the fetal liver (FL) niche is not yet elucidated. We show that Nestin+NG2+ pericytes associate with portal vessels, forming a niche promoting HSC expansion. Nestin+NG2+ cells and HSCs scale during development with the fractal branching patterns of portal vessels, tributaries of the umbilical vein. After closure of the umbilical inlet at birth, portal vessels undergo a transition from Neuropilin-1+Ephrin-B2+ artery to EphB4+ vein phenotype, associated with a loss of peri-portal Nestin+NG2+ cells and emigration of HSCs away from portal vessels. These data support a model in which HSCs are titrated against a peri-portal vascular niche with a fractal-like organization enabled by placental circulation. Characterization of the transcriptome of fetal liver and adult bone marrow niche using RNA-seq
Project description:Mesenchymal stem cells (MSCs) And osteolineage cells contribute to the hematopoietic stem cell (HSC) Niche in the bone marrow of long bones. However, Their developmental relationships remain unclear. Here we demonstrate that different MSC populations in the developing marrow of long bones have distinct functions. Proliferative mesoderm-derived nestin- MSCs participate in fetal skeletogenesis, And lose MSC activity soon after birth. In contrast, Quiescent neural-crest-derived nestin+ Cells in the same bones preserve MSC activity, But do not generate fetal chondrocytes. Instead, They differentiate into HSC-niche-forming MSCs, Helping to establish the HSC niche by secreting Cxcl12. Perineural migration of these cells to the bone marrow requires the ErbB3 receptor. The neonatal Nestin-GFP+ PDGFR- Cell population also contains Schwann-cell precursors, But does not comprise mature Schwann cells. Thus, In the developing bone marrow HSC-niche-forming MSCs share a common origin with sympathetic peripheral neurons and glial cells, And ontogenically distinct MSCs have non-overlapping functions in endochondrogenesis and HSC niche formation. Total RNA was isolated from small numbers of FACS sorted stromal cells, obtained from neonatal Nes-Gfp bone marrow preparations (2 biological replicates). Each independent set of samples was obtained from pooled skeletal elements (long bones and sterna) form multiple littermates.
Project description:Expression profile analysis in steady-state bone marrow-derived GFP+ cells obtained from transgenic mice in which GFP expression is regulated under the nestin gene promoter
Project description:We analysed the transcriptional signature of bone marrow Nestin+ mesenchymal stromal cells extracted from the bone marrow of mice engrafted with human AML cell lines and compared it to the one of untransplanted mice
Project description:Expression profile analysis in steady-state bone marrow-derived GFP+ cells obtained from transgenic mice in which GFP expression is regulated under the nestin gene promoter Three replicates