PubMed · 4565336
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F P Bohatirchuk, J S Campbell, T F Jeletzky. 1972. Bone lamellae.. https://doi.org/10.1159/000143866
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Matrix vesicles (MVs) are extracellular, 100 nM in diameter, membrane-invested particles selectively located at sites of initial calcification in cartilage, bone, and predentin. The first crystals of apatitic bone mineral are formed within MVs close to the inner surfaces of their investing membranes. Matrix vesicle biogenesis occurs by polarized budding and pinching-off of vesicles from specific regions of the outer plasma membranes of differentiating growth plate chondrocytes, osteoblasts, and odontoblasts. Polarized release of MVs into selected areas of developing matrix determines the nonrandom distribution of calcification. Initiation of the first mineral crystals, within MVs (phase 1), is augmented by the activity of MV phosphatases (eg, alkaline phosphatase, adenosine triphosphatase and pyrophosphatase) plus calcium-binding molecules (eg, annexin I and phosphatidyl serine), all of which are concentrated in or near the MV membrane. Phase 2 of biologic mineralization begins with crystal release through the MV membrane, exposing preformed hydroxyapatite crystals to the extracellular fluid. The extracellular fluid normally contains sufficient Ca2+ and PO4(3-) to support continuous crystal proliferation, with preformed crystals serving as nuclei (templates) for the formation of new crystals by a process of homologous nucleation. In diseases such as osteoarthritis, crystal deposition arthritis, and atherosclerosis, MVs initiate pathologic calcification, which, in turn, augments disease progression.
The interaction of bone cells and their underlying extracellular matrix impacts biological processes such as maintenance of tissue integrity. The biological recognition of the extracellular matrix by attached cells is mediated by the activity of integrins that recognize adhesive-specific domains. The most widely recognized adhesive motif is the RGD sequence, common to many of the adhesive matrix molecules. Here, we show that cyclo DFKRG which was previously selected to increase cell adhesion of human bone marrow stromal cells (HBMSC), increases both cell differentiation and mineralization through activation of tyrosine kinases, focal adhesion kinase (p(125)FAK) and Mitogen Activated Protein (MAP) kinases.
OBJECTIVE: To investigate the feasibility of using decalcified bone matrix loaded with mesenchymal stem cells (MSCs) derived from adult human bone marrow as scaffolds for bone tissue engineering. METHODS: Allogenic decalcified bone matrix was prepared. MSCs were isolated from adult human bone marrow with monocyte-separating medium and then cultured in basic medium of mesenchymal stem cells (MSC). The third generation of the cultured cells were identified by FITC-antiCD105, seeded onto allogenic decalcified bone matrix followed by observation under scanning electron microscope and invert microscope a week later. RESULTS: Rapid proliferation of both primary and subcultured MSCs was observed, and CD105-positive cells reached 64.1% among the third generation of the cells. MSCs also grew well and proliferated rapidly after being cultured with decalcified bone matrix. CONCLUSION: Naive MSCs are ideal seeding cells for bone tissue engineering, and the allogenic decalcified bone matrix loaded with MSCs may be used as a good scaffold.