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:Carcinoma-associated fibroblasts (CAFs) that express ?-smooth-muscle-actin (?SMA+) contribute to cancer progression, but their precise origin and role in tumorigenesis is not established. Using mouse models of inflammation-induced gastric cancer, we show that at least 20% of CAFs originate from bone marrow and derive from mesenchymal stem cells (MSCs). Surprisingly, we find that ?SMA+ myofibroblasts (MF) are niche cells normally present in bone marrow and increase markedly in the bone marrow and blood during progression to dysplasia. MSC-derived CAFs that are recruited to the dysplastic stomach express IL-6, Wnt5? and BMP4 and show DNA hypomethylation. Bone marrow (BM)-derived CAFs strongly promote tumor growth in organotypic and xenograft models. In addition, CAFs are generated from MSCs and are recruited to distant tumor sites in a TGF-?- and SDF-1?-dependent manner. Carcinogenesis therefore involves the expansion and relocation of normal bone marrow niche cells to the tumor site where they create a new niche to sustain cancer progression. Since resident (non-BM-derived) CAFs could not be cultured and directly compared to BM-derived CAFs, we additionally isolated total RFP(+) gastric CAFs from aSMA-RFP mice with Helicobacter felis-induced dysplasia, and compared them to GFP(+) BM-derived gastric CAFs from mice with H. felis-induced dysplasia mice that had been transplanted with UBC-EGFP bone marrow. The RFP+ CAFs (HF CAF) represent total CAFs (of which only 20% were BM-derived), while the latter represented only BM-derived CAFs (BM CAF). We compared their gene expression using the Illumina array (MouseWG-6v2) directly after FACS sorting. Interestingly, the GFP+ BM-derived CAFs expressed higher levels of inflammatory genes (IL-6, IL-1?, IL-33) and a number of tumor and stem cell associated factors (CCL5, SPP1, Notch3, MMP9, CD47, CXCR4, PARP10,) compared to the total (RFP+) population of gastric CAFs. Comparison of bone marrow-derived GFP-labeled gastric CAFs versus all gastric CAFs.
Project description:The bone marrow niche plays a critical role in controlling the fate of hematopoietic stem cells (HSCs) by integrating intrinsic and extrinsic signals. However, the molecular events in the HSC niche remain to be investigated. Here, we report that intercellular adhesion molecule-1 (ICAM-1) maintains HSC quiescence and repopulation capacity in the niche. ICAM-1-deficient mice (ICAM-1-/-) displayed significant expansion of phenotypic long-term HSCs with impaired quiescence, as well as favors myeloid cell expansion. ICAM-1-deficient HSCs presented normal reconstitution capacity during serial transplantation; however, reciprocal transplantation experiments showed that ICAM-1 deficiency in the niche impaired HSCs quiescence and repopulation capacity. In addition, ICAM-1 deletion caused failure to retain HSCs in the bone marrow and changed the expression profile of stroma cell-derived factors, possibly representing the mechanism for defective HSCs in ICAM-1-/- mice. Collectively, these observations identify ICAM-1 as a regulator in the bone marrow niche.
Project description:Hematopoietic aging is defined by a loss of regenerative capacity and skewed differentiation from hematopoietic stem cells (HSC) leading to dysfunctional blood production. Signals from the bone marrow (BM) microenvironment dynamically tailor hematopoiesis, but the effect of aging on the niche and the contribution of the aging niche to blood aging still remains unclear. Here, we show the development of an inflammatory milieu in the aged marrow cavity, which drives both niche and hematopoietic system remodeling. We find decreased numbers and functionality of osteogenic endosteal mesenchymal stromal cells (MSC), expansion of pro-inflammatory perisinusoidal MSCs, and deterioration of the central marrow sinusoidal endothelium, which together create a self-reinforcing inflamed BM milieu. Single cell molecular mapping of old niche cells further confirms disruption of cell identities and enrichment of inflammatory response genes. Inflammation, in turn, drives chronic activation of emergency myelopoiesis pathways in old HSCs and multipotent progenitors, which promotes myeloid differentiation at the expense of lymphoid and erythroid commitment, and hinders hematopoietic regeneration. Remarkably, both defective hematopoietic regeneration, niche deterioration and HSC aging can be improved by blocking inflammatory IL-1 signaling. Our results indicate that targeting the pro-inflammatory niche milieu can be instrumental in restoring blood production during aging.
