Multinucleated Tartrate Resistant Acid Phosphatase Positive Cells with Macrophage and Osteoclast Phenotypes in Bone

Prothrombin (PT) and osteopontin (OPN) promotes adhesion of different TRAP-positive multinucleated cells isolated from rat long bone (Hu et al. Exp Cell Res. 2008; 314: 638-50). The PT-adhering cell could represent either an immature precursor to the OPN-adherent osteoclast or constitute a distinct multinucleated cell population with a unique role in bone. Herein, phenotypic differences between PT- and OPN- cells were investigated with microarray- expression analysis. Characteristic for PT-cells was expression of innate immune response genes and scavenger receptors whereas OPN-cells expressed typical osteoclast proteins such as collagenases implicated in bone degradation.