title: Bone marrow subendosteal microenvironment harbours functionally distinct haemosupportive stromal cell populations.
abstract: In adult animals, bone marrow is the major site of blood cell production, which is controlled by interactions between the local stroma and blood cell progenitors. The endosteal/subendosteal environment comprises bone-lining and adjacent reticular cells and sustains haemopoietic stem cell (HSC) self-renewal, proliferation and differentiation. We have questioned the specific role of each of these stroma cells in controlling HSC fate. We have isolated two distinct stroma-cell populations containing subendosteal reticulocytes (F-RET) and osteoblasts (F-OST) from periosteum-free fragments of murine femurs by a two-step collagenase-digestion procedure. Both populations produce similar extracellular matrix (collagen I, laminin, fibronectin, decorin), except for collagen IV, which is low in F-OST. They also express osteogenic markers: osteopontin, osteonectin, bone sialoprotein and alkaline phosphatase (ALP). The quantity and activity of ALP are however higher in F-OST. When co-cultured with bone marrow mononuclear cells or lineage-negative haemopoietic progenitors, F-OST stroma induces low proliferation and high maintenance of early haemopoietic progenitors, whereas F-RET stroma induces high short-term proliferation and differentiation. Analysis by reverse transcription/polymerase chain reaction has revealed higher levels of Jagged-1 expression by F-OST cells than by the F-RET population. Thus, two adjacent stroma cells (subendosteal and endosteal) play distinct roles in controlling the stem-cell capacity and fate of HSC and probably contribute distinctly to HSC niche formation.
authors.affiliation: Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Cidade Universitária, 21941-970, Rio de Janeiro, Brasil.
authors.forename: Alex
authors.initials: A
authors.lastname: Balduino
authors.forename: Sandra P
authors.initials: SP
authors.lastname: Hurtado
authors.forename: Priscilla
authors.initials: P
authors.lastname: Frazão
authors.forename: Christina M
authors.initials: CM
authors.lastname: Takiya
authors.forename: Leandro M
authors.initials: LM
authors.lastname: Alves
authors.forename: Luiz-Eurico
authors.initials: LE
authors.lastname: Nasciutti
authors.forename: Márcia C
authors.initials: MC
authors.lastname: El-Cheikh
authors.forename: Radovan
authors.initials: R
authors.lastname: Borojevic
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism* / Q000648:ultrastructure; D002454:Cell Differentiation; D002478:Cells, Cultured; D018920:Coculture Techniques; D017364:Collagenases / Q000494:pharmacology; D004727:Endothelium / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D005269:Femur / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D019084:Fluorescent Antibody Technique, Indirect; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000648:ultrastructure; D007150:Immunohistochemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism / Q000648:ultrastructure; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017154:Stromal Cells / Q000378:metabolism* / Q000648:ultrastructure; D014357:Trypsin / Q000494:pharmacology
chemical_list: D015415:Biomarkers; D000469:Alkaline Phosphatase; D014357:Trypsin; D017364:Collagenases