Formation of osteoclast‐like cells from peripheral blood of periodontitis patients occurs without supplementation of macrophage colony‐stimulating factor

Abstract

To determine whether peripheral blood mononuclear cells (PBMCs) from chronic periodontitis patients differ from PBMCs from matched control patients in their capacity to form osteoclast-like cells. PBMCs from 10 subjects with severe chronic periodontitis and their matched controls were cultured on plastic or on bone slices without or with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB ligand (RANKL). The number of tartrate-resistant acid phosphatase-positive (TRACP(+)) multinucleated cells (MNCs) and bone resorption were assessed. TRACP(+) MNCs were formed under all culture conditions, in patient and control cultures. In periodontitis patients, the formation of TRACP(+) MNC was similar for all three culture conditions; thus supplementation of the cytokines was not needed to induce MNC formation. In control cultures, however, M-CSF or M-CSF/RANKL resulted in higher numbers compared with cultures without cytokines. Upregulations of osteoclast marker mRNA cathepsin K and carbonic anhydrase II confirmed the osteoclastic character. Bone resorption was only observed when PBMCs were cultured in the presence of M-CSF and RANKL. Our data indicate that PBMCs from periodontitis patients do not need priming by M-CSF to become osteoclast-like cells, suggesting that PBMCs from periodontitis patients are present in the circulation in a different state of activity.