The proliferative human monocyte subpopulation contains osteoclast precursors.
BACKGROUND
Immediate precursors of bone-resorbing osteoclasts are cells of the monocyte/macrophage lineage. Particularly during clinical conditions showing bone loss, it would appear that osteoclast precursors are mobilized from bone marrow into the circulation prior to entering tissues undergoing such loss. The observed heterogeneity of peripheral blood monocytes has led to the notion that different monocyte subpopulations may have special or restricted functions, including as osteoclast precursors.


METHODS
Human peripheral blood monocytes were sorted based upon their degree of proliferation and cultured in macrophage colony-stimulating factor (M-CSF or CSF-1) and receptor activator of nuclear factor-kappa-B ligand (RANKL).


RESULTS
The monocyte subpopulation that is capable of proliferation gave rise to significantly more multinucleated, bone-resorbing osteoclasts than the bulk of the monocytes.


CONCLUSIONS
Human peripheral blood osteoclast precursors reside in the proliferative monocyte subpopulation.
Lari
Roya
R
Department of Medicine and Cooperative Research Centre for Chronic Inflammatory Diseases, University of Melbourne, The Royal Melbourne Hospital, Parkville, Victoria 3050, Australia. royalari@gmail.com
Kitchener
Peter D
PD
Hamilton
John A
JA
D000135:Acid Phosphatase / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods; D002454:Cell Differentiation / Q000502:physiology; D019070:Cell Lineage / Q000502:physiology*; D049109:Cell Proliferation; D005434:Flow Cytometry; D015870:Gene Expression; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase
D007527:Isoenzymes; D053245:RANK Ligand; D012333:RNA, Messenger; C505688:TNFSF11 protein, human; D016173:Macrophage Colony-Stimulating Factor; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase