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.
A prospective in vivo assay was used to identify cells with potential for multiple lineage differentiation. With this assay it was first determined that the 5-FU resistant cells capable of osseous tissue formation in vivo also migrated towards SDF-1 in vitro. In parallel, an isolation method based upon fluorescence activated cell sorting (FACS) was employed to identify a very small cell embryonic-like (VSEL) Lin−Sca-1+ CD45− cell that with as few as 500 cells were capable of forming bone-like structures in vivo. Differential marrow fractionation studies determined that the majority of the Lin−Sca-1+CD45− cells reside in the subendosteal regions of marrow. To determine if these cells were capable of differentiating into multiple lineages, stromal cells harvested from Col2.3ΔTK mice were implanted with a gelatin sponge into SCID mice to generate thymidine kinase sensitive ossicles. At 1.5 months, 2000 GFP+ Lin−Sca-1+ CD45− cells were injected into the ossicles. At harvest, co-localization of GFP expressing cells with antibodies to the osteoblast specific marker Runx-2 and the adipocyte marker PPARγ were observed. Based upon the ability of the non-cultured cells to differentiate into multiple mesenchymal lineages in vivo and the ability to generate osseous tissues at low density, we propose that this population fulfills many of the characteristics of mesenchymal stem cells.
: We concluded that Aa, Pg, Pi, Td, and Tf are present in healthy and diseased conditions. Therefore, these periodontal pathogens are not strictly related to periimplant disease sites.
Purpose To compare the clinical and laboratory outcomes of intra-articular injections of culture-expanded bone-derived mesenchymal stem cells (MSCs) with or without platelet-rich plasma (PRP) to intra-articular corticosteroid injections for the treatment of knee osteoarthritis (OA). Methods Forty-seven patients with radiographic and symptomatic knee OA were randomized into three groups for intraarticular injections: autologous bone marrow-derived culture-expanded MSCs (n = 16); autologous bone marrow-derived culture-expanded MSCs + PRP (n = 14); and corticosteroid (n = 17). The outcomes were assessed by the Knee Injury and Osteoarthritis Outcome Score (KOOS) and range of motion (ROM) at baseline, 1, 2, 3, 6, 9 and 12 months and intra-articular cytokines analysis at baseline, 6 and 12 months postoperatively. Results The three groups showed significant improvement in most KOOS domains and global score at 1st month and all domains and global score at 12-month follow-up (p < 0.05). At the 1st month, only the MSCs group showed significant differences in KOOS symptoms domain (p = 0.003). The MSCs and MSCs + PRP groups showed the highest percentage of improvement in most KOOS domains and global score compared to the corticosteroid group. All three groups showed a significant reduction in intra-articular levels of human interleukin-10 cytokine, from baseline to 12 months (p < 0.05). Conclusion An intra-articular injection of bone marrow-derived culture-expanded MSCs with or without the addiction of PRP is effective in improving the function and decreasing symptoms caused by knee OA at 12-month follow-up. Level of evidence II.
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