Year: 2014
Type: article
Abstract: Introduction: Healthy bone constantly remodels, in balance between osteoclast bone resorption and osteoblast bone formation.Osteoclasts differentiate in vitro from osteoclast progenitor cells in the presence of macrophage-colony stimulating factor and receptor activated nuclear factor B-ligand, while osteoblasts differentiate in vitro from mesenchymal stem cells in the presence of ascorbic acid, -glycerol phosphate, and dexamethasone.Imbalance between the function of osteoclasts and osteoblasts results in disease.In osteoporosis, bone resorption dominates, leading to decreased bone mass.Osteoporosis is of critical concern to an aging population, and new treatments are needed.Osteoactivin is an anabolic bone growth factor in vivo, causing increased bone mass when injected into mice.In vitro, osteoactivin has been shown to increase osteoblast differentiation and function.However, the effects of osteoactivin on osteoclasts are not as well defined.In this study, we hypothesized that recombinant osteoactivin inhibits osteoclastogenesis.In the future, osteoactivin could be a therapeutic agent for bone healing and preventing or even reversing osteoporosis. Material and Methods:Osteoclast progenitor cells were isolated from C57BL/6 murine tibias, femurs, and humeri.Several aspects of osteoclastogenesis were tested in the presence of dose-dependent recombinant osteoactivin.First, proliferation and survival iii assays, with and without macrophage-colony stimulating factor respectively, were conducted on the osteoclast progenitor cells in the presence of recombinant osteoactivin.Next, the osteoclast progenitor cells were differentiated into osteoclasts in the presence of recombinant osteoactivin.Osteoclast tartrate resistant acid phosphatase activity was measured and stained as a marker for terminally differentiated osteoclasts.Differential cell counting was performed for osteoclasts containing 3-20 and >20 nuclei.Two functional assays, Corning surface and cortical bovine bone slices, were performed as well in order to quantify osteoclast resorption activity in the presence of recombinant osteoactivin.Finally, osteoclast survival in the presence of recombinant osteoactivin was tested without receptor activated nuclear factor kB-ligand.Results: Osteoclast progenitor cell proliferation and survival showed no differences from control when treated with recombinant osteoactivin.Likewise, when recombinant osteoactivin was added on the first day of osteoclast differentiation, there were negligible changes.However, when administered on day 4 or day 6 of differentiation, recombinant osteoactivin treatment resulted in fewer osteoclasts with >20 nuclei.In the Corning functional assay, recombinant osteoactivin administered on day 1 and day 4 of differentiation increased resorption, but day 6 administration decreased resorption, although not significantly.Meanwhile, in the cortical bone slice functional assay, previ
Author: Matthew Khol
Institution: Northeast Ohio Medical University
Language: English
Topic: Bone Metabolism and Diseases
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2508847481