Adhesion of osteoclasts and monocytes to developing bone

Area of Science:

• Cell Biology
• Developmental Biology
• Biomineralization

Background:

• Osteoclast activity is essential for bone matrix resorption during development.
• Cell attachment to bone precedes osteoclast-mediated resorption.

Purpose of the Study:

• To develop an in vitro assay for measuring osteoclast and monocyte adhesion to embryonic chick bone.
• To investigate the affinity of osteoclasts and monocytes for different bone developmental stages and surfaces.

Main Methods:

• Isolated osteoclasts and monocytes from embryonic chicks were labeled with (32P)-KH2PO4.
• Cells were incubated with embryonic chick tibias (varying developmental stages) and control cell types.
• Quantified cell attachment to endosteal and periosteal bone surfaces.

Main Results:

• Osteoclasts and monocytes exhibited twice the adhesion to bone compared to fibroblasts and limb mesenchymal cells.
• No selective adhesion was observed between endosteal and periosteal bone surfaces.
• Cell attachment varied with embryonic bone developmental age, with day 12 bone showing higher adhesion than day 19 bone; cartilage bound few cells.

Conclusions:

• Osteoclasts and monocytes possess a high affinity for bone.
• The developmental age and substrate composition significantly influence osteoclast and monocyte bone adhesion.