Characterization of osteoclast precursors in human blood

Abstract

Osteoclast precursors (OCPs) circulate in the mononuclear fraction of peripheral blood (PB), but their abundance and surface characteristics are unknown. Previous studies suggest that the receptor activator for NF‐κB (RANK) on cytokine‐treated OCPs in mouse bone marrow interacts with osteoprotegerin ligand (OPGL/TRANCE/RANKL/ODF) to initiate osteoclast differentiation. Hence, we used a fluorescent form of human OPGL (Hu‐OPGL‐F) to identify possible RANK‐expressing OCPs in untreated peripheral blood mononuclear cells (PBMCs) using fluorescence‐activated cell sorting analysis. Monocytes [CD14‐phycoerythrin (PE) antibody (Ab) positive (+) cells, 10–15% of PBMCs] all (98–100%) co‐labelled with Hu‐OPGL‐F (n > 18). T lymphocytes (CD3‐PE Ab+ cells, 66% of PBMCs) did not bind Hu‐OPGL‐F; however, B cells (CD19‐PE Ab+ cells, 9% of PBMCs) were also positive for Hu‐OPGL‐F. All Hu‐OPGL‐F+ monocytes also co‐labelled with CD33, CD61, CD11b, CD38, CD45 and CD54 Abs, but not CD34 or CD56 Abs. Hu‐OPGL‐F binding was dose dependent and competed with excess Hu‐OPGL. When Hu‐OPGL‐F+, CD14‐PE Ab+, CD33‐PE Ab+, Hu‐OPGL‐F+/CD14‐PE Ab+ or Hu‐OPGL‐F+/CD33‐PE Ab+ cells were cultured with OPGL (20 ng/ml) and colony‐stimulating factor (CSF)‐1 (25 ng/ml), OC‐like cells readily developed. Thus, all freshly isolated monocytes demonstrate displaceable Hu‐OPGL‐F binding, suggesting the presence of RANK on OCPs in PB; also, OCPs within a purified PB monocyte population form osteoclast‐like cells in the complete absence of other cell types in OPGL and CSF‐1 containing medium.

Modulation of osteoclastogenesis in porcine bone marrow cultures by quercetin and rutin

“…Osteoclast lineage cells express several markers, including calcitonin and vitronectin receptors, acid phosphatases, src kinase, carbonic anhydrase, proteinases, and the surface molecule RANK, a member of the tumor necrosis factor family that is essential for osteoclastogenesis and osteoclast survival (Hsu et al 1999;Duong and Rodan 2001). Mouse (Hsu et al 1999) and rat (Ikeda et al 2000) osteoclast progenitors contain RANK mRNA, and RANK protein is present in human blood monocytes (Shalhoub et al 2000). Moreover, the differentiation and activity of osteoclasts are modulated by several factors produced by stromal/osteoblastic cells, including macrophage-colony stimulating factor, several cytokines, RANK ligand, and osteoprotegerin (Duong and Rodan 2001).…”

Inhibitory effects of ursolic acid on osteoclastogenesis and titanium particle-induced osteolysis are mediated primarily via suppression of NF-κB signaling

“…Osteoclasts, specializing in bone resorption, are polykaryons formed by cytoplasmic fusion of mononuclear hematopoietic precursors of the monocyte- macrophage lineage residing in the bone marrow [31]. Bone resorption, which is the unique function of osteoclasts and closely related to bone mineral density (BMD), only occurs when a sealing zone is formed by an F-actin ring structure [32].…”

Biochemical markers in preclinical models of osteoporosis

“…The models range from very simple in vitro testing systems for resorption and formation (Baron et al 1985, Nefussi et al 1985, Bellows et al 1986, Nordstrom et al 1995, Li et al 1999, Massey & Flanagan 1999, Shalhoub et al 2000, Rawadi et al 2003, Ogasawara et al 2004, to the more complex ex vivo systems (Dieudonne et al 1991, Blavier & Delaisse 1995, Mundy et al 1999, Engsig et al 2000a, Chiusaroli et al 2003, Garrett 2003, and finally to the in vivo models, such as the rat ovariectomised (OVX) model, which mimics human osteoporosis to some extent (Vanderschueren et al 1992, Dempster et al 1995, Cenci et al 2000, Wu et al 2003.…”