Hydroxyapatite surface roughness: complex modulation of the osteoclastogenesis of human precursor cells

Area of Science:

• Biomaterials Science
• Cell Biology
• Tissue Engineering

Background:

• Surface roughness influences bone cell behavior, but its effect on osteoclastogenesis is not well understood.
• Osteoclastogenesis, the formation of bone-resorbing cells, is crucial for bone remodeling.
• Understanding how surface properties affect osteoclast formation is vital for designing effective bone implants.

Purpose of the Study:

• To investigate the effect of varying surface roughness on osteoclast differentiation.
• To compare osteoclastogenic behavior using different stimuli: soluble factors versus cell-to-cell contact.
• To elucidate the role of surface topography in osteoclast formation on hydroxyapatite.

Main Methods:

• Human peripheral blood mononuclear cells (PBMCs) and human bone marrow cells (hBMCs) were cultured on hydroxyapatite disks with varied surface roughness (Ra 0.0437–0.582 μm).
• Cells were cultured alone or co-cultured, with or without M-CSF and RANKL (osteoclastogenic inducers), for 21 days.
• Osteoclast differentiation was assessed by evaluating multinucleated cell formation, actin ring presence, gene expression (TRAP, cathepsin K, etc.), TRAP activity, and resorbing activity.

Main Results:

• Osteoclast differentiation markers were observed in PBMCs treated with M-CSF/RANKL or co-cultured with hBMCs.
• Osteoclastogenic response in PBMCs with M-CSF/RANKL increased with surface roughness.
• Osteoclastogenic response in PBMCs co-cultured with hBMCs decreased with surface roughness, but remained high with added inducers.

Conclusions:

• The influence of surface roughness on osteoclast differentiation is stimulus-dependent.
• Soluble factors (M-CSF/RANKL) promote a roughness-dependent osteoclast response.
• Direct cell-to-cell contact between osteoblastic and osteoclastic cells leads to a less pronounced, roughness-independent osteoclast response.