Early reversal cells in adult human bone remodeling: osteoblastic nature, catabolic functions and interactions with osteoclasts

Mohamed Essameldin Abdelgawad, Jean-Marie Delaissé, Maja Hinge, Pia Rosgaard Jensen, Ragad Walid Alnaimi, Lars Rolighed, Lars H. Engelholm, Niels Marcussen, Thomas Levin Andersen

    35 Citations (Scopus)

    Abstract

    The mechanism coupling bone resorption and formation is a burning question that remains incompletely answered through the current investigations on osteoclasts and osteoblasts. An attractive hypothesis is that the reversal cells are likely mediators of this coupling. Their nature is a big matter of debate. The present study performed on human cancellous bone is the first one combining in situ hybridization and immunohistochemistry to demonstrate their osteoblastic nature. It shows that the Runx2 and CD56 immunoreactive reversal cells appear to take up TRAcP released by neighboring osteoclasts. Earlier preclinical studies indicate that reversal cells degrade the organic matrix left behind by the osteoclasts and that this degradation is crucial for the initiation of the subsequent bone formation. To our knowledge, this study is the first addressing these catabolic activities in adult human bone through electron microscopy and analysis of molecular markers. Periosteoclastic reversal cells show direct contacts with the osteoclasts and with the demineralized resorption debris. These early reversal cells show (1) ¾-collagen fragments typically generated by extracellular collagenases of the MMP family, (2) MMP-13 (collagenase-3) and (3) the endocytic collagen receptor uPARAP/Endo180. The prevalence of these markers was lower in the later reversal cells, which are located near the osteoid surfaces and morphologically resemble mature bone-forming osteoblasts. In conclusion, this study demonstrates that reversal cells colonizing bone surfaces right after resorption are osteoblast-lineage cells, and extends to adult human bone remodeling their role in rendering eroded surfaces osteogenic.

    Original languageEnglish
    JournalHistochemistry and Cell Biology
    Volume145
    Issue number6
    Pages (from-to)603-615
    Number of pages13
    ISSN0948-6143
    DOIs
    Publication statusPublished - 2016

    Keywords

    • Catabolism
    • Collagenolysis
    • Interaction
    • Osteoblast
    • Osteoclast
    • Reversal cells
    • Reversal phase

    Fingerprint

    Dive into the research topics of 'Early reversal cells in adult human bone remodeling: osteoblastic nature, catabolic functions and interactions with osteoclasts'. Together they form a unique fingerprint.

    Cite this