OBJECTIVETo establish a culture method for a large amount of highly purified osteoclast-like cells in vitro. To investigate the gene expression of some osteoclast marker enzymes. To lay the foundation for the further study of the signal path on the differentiation and formation of osteoclast-like cells.

METHODSThe bone marrow mononuclear cells of rat were treated with 30 ng/mL macrophagecolony-stimulating factor (M-CSF) and 50 ng/mL receptor activator of NF-kappaB ligand (RANKL) and cultured for 6 days. After culturing, cells were evaluated by morphology observation, tartrate-resistant acid phosphatase (TRAP) staining, Giemsa staining, pit staining, and the gene expression of some osteoclast marker enzymes.

RESULTSThe TRAP-positive mononuclear cells were more frequently observed than the multinucleated cells and pit staining could be seen on the dentine slice. The transcription expression of TRAP, matrix metalloproteinase-9 (MMP-9), membrane-type1-matrix metalloproteinase (MT1-MMP) and cathepsin K were detected by RT-PCR.

CONCLUSIONThe cooperation of M-CSF and RANKL could induce a large amount of highly purified osteoclast-like cells formation in rat bone marrow culture. The typical characteristics of osteoclast-like cells were demonstrated and the enriched osteoclast-like cells expressed TRAP, MMP-9, MT1-MMP and cathepsin K.