The hematopoietic stem cell in its place.

Center for Regenerative Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02114, USA.
Nature Immunology (Impact Factor: 24.97). 05/2006; 7(4):333-7. DOI: 10.1038/ni1331
Source: PubMed

ABSTRACT A signature characteristic of stem cells is their ability to self-renew, affording a theoretically limitless ability to produce daughter cells and their descendents. This near-timeless dimension of stem cell function is not free of the constraints of place. The idea that highly specialized 'microenvironmental' cues participate in the regulation of stem cells has evidence in classic embryology and more recently in adult stem cells through the use of model organisms. There is now ample evidence that an anatomically defined, specifically constituted place represents the niche for hematopoietic and other tissue-specific stem cells. This review provides a conceptual framework and detailed account of the hematopoietic stem cell niche as defined at present. The components are assembling into a more complex view of the niche and may now be amenable to examination as a system and possibly to alteration to affect outcomes in immune regeneration.

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    ABSTRACT: Mesenchymal stromal cells (MSCs) represent a small and heterogeneous subpopulation of mesenchymal stem cells that possesses multilineage differentiation potential. These cells are mainly present in bone marrow, but also in other tissues, and represent a valuable resource for their ability to differentiate into different cell lines and for many therapeutic approaches. MSCs are able to differentiate into cells of mesodermal origin such as adipocytes, chondrocytes, osteoblasts or fibroblasts and in vitro also into cells of non-mesodermal lineages. In bone marrow, they establish the microenvironment for the growth and differentiation of the hematopoietic stem cells (HSCs) resulting crucial for HSC maintenance and haematopoiesis. Nevertheless, the proliferation and/or the survival rate of MSCs may contribute to the onset of different types of bone sarcomas, such as Osteosarcoma, Chondrosarcoma and Giant Cell Tumor of Bone that represent the result of neoplastic degeneration of their corresponding committed mesenchymal precursors, probably as a consequence of the alteration of different or common biochemical pathways.
  • Frontiers in Bioscience 01/2010; 15(1):854. DOI:10.2741/3650 · 4.25 Impact Factor
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    ABSTRACT: Hematopoietic stem and progenitor cells (HSPCs) have been used successfully to treat patients with cancer and disorders of the blood and immune systems. In this study, we tried to enrich HSPCs by implanting biomaterials into the spatium intermusculare of mice hind limbs. Gelatine sponges were implanted into the spatium intermusculare of mice and then retrieved after 12 days. The presence of HSPCs in the migrating cells (MCs) was detected by phenotypically probing with CD34(+)Sca-1(+) and functionally confirming the presence of using colony-forming cell assay and assessing the long-term reconstitution ability. The frequency of CD34(+), Sca-1(+), and CD34(+)Sca-1(+) cells and colony formation unit in the MCs was much higher than that in the bone marrow (BM). Moreover, transplanted MCs were able to home to BM, muscle, and spleen, which induced an efficient long-term hematopoietic reconstitution in vivo. In addition, HSPCs within the MCs originated from the BM. Furthermore, the administration of G-CSF greatly reduced the time of implantation, and increased the number of MCs and frequency of HSPCs in the MCs. These data provide compelling evidence that HSPCs can be enriched by implanting biomaterial into spatium intermusculare. Implantation of biomaterial may be seen as the first step to a proof of their applicability to clinical practice in enriching HSPCs.
    BioMed Research International 01/2015; 2015:398642. DOI:10.1155/2015/398642 · 2.71 Impact Factor


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