title: Multiple roles of M-CSF in human osteoclastogenesis.
abstract: Although the critical role of M-CSF in osteoclastogenesis is well documented, there has been no detailed analysis of how it regulates human osteoclast formation and function in vitro. We used a human osteoclastogenesis model employing CFU-GM osteoclast precursors cultured for 14 days on dentine with RANKL, with varying exposure to exogenous human M-CSF. Short-term treatment of precursors with M-CSF (10-100 ng/mL) resulted in increased proliferation with or without RANKL. Treatment with M-CSF (1-100 ng/mL) for 14 days caused a biphasic concentration-dependent stimulation of formation, fusion, and resorption peaking at 10-50 ng/mL and almost complete abolition of resorption at 100 ng/mL. Time-course studies using M-CSF (25 ng/mL) showed that osteoclast size, nuclei/cell, and resorption increased with longer duration of M-CSF treatment. When treatment was restricted to the first 4 days, M-CSF (25-100 ng/mL) stimulated formation of normal numbers of osteoclasts that resorbed less. Blockade of endogenous M-CSF signaling with neutralizing M-CSF antibody during the first week of culture extensively inhibited osteoclastogenesis, whereas blockade during the second week produced only a small reduction in resorption. Treatment with M-CSF during the second week of culture caused a small increase in osteoclast number and a concentration-dependent increase in cytoplasmic spreading with inhibition of resorption. We have shown that M-CSF modulates multiple steps of human osteoclastogenesis, including proliferation, differentiation and fusion of precursors. In the later stages of osteoclastogenesis, M-CSF modulates osteoclast-resorbing activity, but is not required for survival. Modulation of M-CSF signaling is a potential therapeutic target for conditions associated with excess bone resorption.
authors.affiliation: The Department of Clinical and Biomedical Sciences: Barwon Health, The University of Melbourne, Geelong, Victoria 3220, Australia. jasonh@barwonhealth.org.au
authors.forename: Jason M
authors.initials: JM
authors.lastname: Hodge
authors.forename: Mark A
authors.initials: MA
authors.lastname: Kirkland
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Nicholson
mesh_terms: D001862:Bone Resorption; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism; D008954:Models, Biological; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D008562:Membrane Glycoproteins; D016173:Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor