Abstract
Osteoclasts are multinucleated cells responsible for bone resorption. Several lines of evidence have indicated that osteoclasts are derived from hemopoietic stem cells. However, the nature of osteoclast progenitors and their differentiation process into osteoclasts are still not known. We previously reported that osteoclast-like multinucleated cells were formed in mouse marrow cultures and in co-cultures of mouse spleen cells and osteoblastic cells. Using these culture systems, we studied the nature and differentiation process of osteoclast progenitors. Following results were obtained: 1) Osteoclasts are erived from not only immature cells but also mature cells of the monocyte-macrophage lineage.2 ) Osteclast progenitors differentiate into osteoclasts through the interaction of cell-to-cell contact with osteoblastic cells.3) M-CSF produced by osteoblastic cells is an important factor for maintaining growth and differentiation of osteoclast progenitors. These findings have significant implications for the study ofosteoclast biology.
