Origin of osteoclasts: mature monocytes and macrophages are capable of differentiating into osteoclasts under a suitable microenvironment prepared by bone marrow-derived stromal cells.

Abstract

We previously reported that osteoclast-like cells were formed in cocultures of a mouse marrow-derived stromal cell line (ST2) with mouse spleen cells in the presence of la,25-dihydroxyvitamin D3 and dexamethasone. In this study, we developed a new coculture system to determine the origin of osteoclasts. When relatively small numbers of mononuclear cells (103-105 cells per well) obtained from mouse bone marrow, spleen, thymus, or peripheral blood were cultured for 12 days on the ST2 cell layers, they formed colonies with a linear relationship between the number of colonies formed and the number of hemopoietic cells inoculated. Tartrate-resistant acid phosphatase (TRAPase)-positive mononuclear and multinucleated cells appeared in the colonies (TRAPase-positive colonies) in response to la,25-dihydroxyvitamin D3 and dexamethasone. When hemopoletic cells suspended in a collagengel solution were cultured on the ST2 cell layers to prevent their movement, TRAPase-positive colonies were similarly formed, indicating that each colony originated from a single cell. All of the colonies consisted of nonspecific esterase-positive cells. The monocyte-depleted population prepared from peripheral blood failed to form colonies, whereas the monocyte-enriched population produced a large number of TRAPase-positive colonies. In addition, alveolar macrophages formed TRAPase-positive colonies most efficiently on the ST2 cell layers in the presence of the two hormones. Salmon 12'I-labeled calcitonin specifically bound to the TRAPase-positive cells. Resorption lacunae were formed on dentine slices on which cocultures were performed. When direct contact between the peripheral blood cells and the ST2 cells was inhibited by a collagen-gel sheet, no TRAPasepositive cells were formed. These results indicate that osteoclasts are also derived from the mature monocytes and macrophages when a sulitable microenvironment is provided by bone marrow-derived stromal cells.Osteoclasts are multinucleated cells responsible for bone resorption. It is evident from chicken-quail chimera experiments (1), parabiosis experiments (2, 3), and marrow transplantation studies in osteopetrotic animals (4, 5) that osteoclasts are derived from circulating mononuclear precursors in hemopoietic tissues. However, the nature and the differentiation process of osteoclast precursors are still not known.We recently reported that osteoclast-like multinucleated cells were formed in response to osteotropic hormones in cocultures of mouse spleen cells with osteoblast-rich cell populations freshly isolated from fetal mouse calvaria (6). These multinucleated cells had the typical characteristics of osteoclasts such as tartrate-resistant acid phosphatase (TRAPase), abundant calcitonin receptors, and the ability to form resorption lacunae on dentine slices (6). Then we reported that the two marrow-derived stromal cell lines, MC3T3-G2/ PA6 and ST2, could be substituted for primary osteoblastrich cell populations in inducing osteoclast-like cells in cocultures with spleen cells...

Osteoprotegerin exposure at different stages of osteoclastogenesis differentially affects osteoclast formation and function

“…Osteoclasts, which are terminally differentiated cells derived from hematopoietic progenitors in the monocyte/macrophage lineage, play an essential role in bone homeostasis by carrying out the controlled bone resorption essential for bone remodeling (Udagawa et al 1990). Osteoclastogenesis is a multistep process that involves progenitor survival, differentiation to mononuclear preosteoclasts, fusion to form multinucleate mature osteoclasts, and activation of mature osteoclasts to produce cells capable of bone resorption (Xing et al 2012).…”

Lipopolysaccharide-Induced Osteoclastogenesis from Mononuclear Precursors: A Mechanism for Osteolysis in Chronic Otitis

“…Ocs, the only cells capable of carrying out bone resorption, are multinucleated cells that form by fusion of bone marrow-derived mononuclear precursors (Udagawa et al 1990). It has been well established that Oc formation from monocyte Oc precursors (pOcs) is regulated by two essential cytokines: receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF;Felix et al 1990;Lacey et al 1998).…”

Decoy receptor 3 (DcR3) induces osteoclast formation from monocyte/macrophage lineage precursor cells

“…3 In vitro studies have shown that osteoclasts in both mouse and humans may form directly from precursor cell populations of monocytes and macrophages. 4 To date, at least two key molecules that are essential and sufficient to the promotion of osteoclastogenesis have been identified, that is, macrophage colony-stimulating factor (M-CSF) and the receptor for activation of NF-kB ligand (RANKL). 5 M-CSF, which is imperative for macrophage maturation, binds to its receptor on early osteoclast precursors, thereby providing signals required for their survival, proliferation, and differentiation.…”

“…5 M-CSF, which is imperative for macrophage maturation, binds to its receptor on early osteoclast precursors, thereby providing signals required for their survival, proliferation, and differentiation. 4,6 RANKL, on the other hand, binds to receptors for activation of NF-kB (RANK) and induces signals necessary for both differentiation and activation of osteoclasts. 2,7,8 In addition to M-CSF and RANKL, various cytokines and hormones have been shown to play roles in the differentiation of pluripotent osteoclast progenitors into mature multinucleated osteoclasts, 5,9 such as interleukin-1b (IL-1b), 10 interleukin-6 (IL-6), 11 interleukin-11, 12 transforming growth factor-b (TGF-b), 13 1a, 25-dihydroxyvitamin D 3, 14 glucocorticoids, 5 and tumor necrosis factor-a (TNF-a).…”