Deficiency of Osteoclasts in Osteopetrotic Mice Is Due to a Defect in the Local Microenvironment Provided by Osteoblastic Cells*

Abstract

We have reported that osteoblastic cells are required for differentiation of osteoclast progenitors in splenic tissues into multinucleated osteoclasts. In the present study we examined the pathogenesis of the osteoclast deficiency in osteopetrotic (op/op) mice using a coculture system of spleen cells and osteoblastic cells. When spleen cells obtained from op/op or normal (+/?) littermates of op/+ parent mice were cocultured with osteoblastic cells obtained from calvaria of normal ddy strain mice, numerous tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells (MNCs) were formed in the presence of 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3]. Most of the TRAP-positive MNCs bound [125I]salmon calcitonin. This suggests that there is no abnormality in the osteoclast progenitors present in the splenic tissues of op/op mice. When osteoblastic cells from +/? littermates were cocultured with normal spleen cells from ddy mice, TRAP-positive MNCs were similarly formed in response to 1 alpha,25(OH)2D3. In contrast, in cocultures of op/op osteoblastic cells with normal spleen cells, no TRAP-positive cells appeared, even in the presence of 1 alpha,25(OH)2D3. The op/op mutation was recently reported to exist in the coding region of the macrophage colony-stimulating factor (M-CSF) gene. Adding M-CSF and 1 alpha,25(OH)2D3 to the coculture with op/op osteoblastic cells induced the appearance of TRAP-positive MNCs with calcitonin receptors. These results clearly indicate that osteoclast deficiency in op/op mice is due to a defect in the local microenvironment in bone, in which M-CSF produced by osteoblastic cells plays a critical role in osteoclast development.

Osteoclast differentiation factor is a ligand for osteoprotegerin/osteoclastogenesis-inhibitory factor and is identical to TRANCE/RANKL

“…M-CSF produced by osteoblasts͞stromal cells appears to be essential for the proliferation and differentiation of osteoclast progenitors (27)(28)(29)(30)(31). This is consistent with our observation that M-CSF was indispensable for ODF-mediated OCL formation.…”

Requirement for NF-κB in osteoclast and B-cell development

“…Previous studies of naturally occurring or genetically engineered forms of osteopetrosis indicate that failure of osteoclast formation may result from defects associated with either accessory (osteoblast/stromal) cells or with cells of the osteoclast lineage (Yoshida et al 1990;Soriano et al 1991;Takahashi et al 1991;Wang et al 1992;Grigoriades et al 1994;Tondravi et al 1997). To address this issue we performed in vitro coculture experiments in which the generation of functional osteoclasts from splenic precursors is dependent on supportive stromal cells/osteoblasts.…”

Cellular, Molecular, and Genetic Determinants of Tooth Eruption

“…Two molecules, CSF-1 and MCP-1, are prime candidates for recruiting the osteoclast precursors (mononuclear cells) into the DF. Although it is known that CSF-1 is required for the formation of osteoclasts from monocytes (mononuclear cells) (e.g., see Kodama et al, 1991;Takahashi et al, 1991;Tanaka et al, 1993;Felix et al, 1990b), it also is a chemoattractant for monocytes in vitro (Wang et al, 1988;Bober et al, 1995). Monocyte chemotactic protein-1 (MCP-1) is a well-known chemokine for monocytes (Rollins et al, 1988;Yoshimura et al, 1991) and is found in a variety of cell types, including fibroblasts (Yu and Graves, 1995).…”

“…The proliferation and differentiation of osteoclast progenitors require CSF-1 (e.g., see Felix et al, 1990b;Kodama et al, 1991;Takahashi et al, 1991;Tanaka et al, 1993). Once the progenitor cells are formed, CSF-1 appears to be indispensable for osteoclast formation (Yasuda et al, 1998a(Yasuda et al, , 1999Jimi et al, 1999).…”