Research article

The proliferative human monocyte subpopulation contains osteoclast precursors

Roya Lari¹ , Peter D Kitchener² and John A Hamilton¹

¹  Department of Medicine and Cooperative Research Centre for Chronic Inflammatory Diseases, University of Melbourne, The Royal Melbourne Hospital, Parkville, Victoria 3050, Australia

²  Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Victoria 3010, Australia

author email corresponding author email

Arthritis Research & Therapy 2009, 11:R23doi:10.1186/ar2616

Published:	17 February 2009

See related editorial by Ritchlin, http://arthritis-research.com/content/11/3/113

Abstract

Introduction

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.