A NOVEL CULTURE SYSTEM TO GENERATE OSTEOCLASTS AND BONE-RESORPTION USING PORCINE BONE-MARROW CELLS - ROLE OF M-CSF

A novel osteoclast generation and bone resorption assay system is desc ribed in which enhanced osteoclastic generation and bone resorption is induced in porcine bone marrow cell cultures cultured in low-serum me dium supplemented with fibroblastic cell (L929) conditioned medium (CM ). Numerous osteoclasts, which could be identified by TRAP staining an d specific labelling with 121F antibody, were generated in a time-depe ndent and L929-CM concentration-dependent fashion. A specific antibody against murine M-CSF/CSF-1 abolished osteoclast formation indicating that M-CSF is the essential component of the L929-CM driven osteoclast generation. Culturing on devitalized bone slices resulted in extensiv e osteoclast-mediated resorption as visualized microscopically. After 16 days in culture, pratically the entire bone slice surface was excav ated by the osteoclastic cells. Bone resorption could be monitored wit h time using a novel enzyme-linked immunoassay measuring type I collag en N-telopeptides in culture supernatants. Release of collagen fragmen ts from the slices was paralleled by osteoclastic secretion of TRAP, S almon calcitonin significantly inhibited collagen fragment and TRAP re lease. 1,25-Dihydroxyvitamin D-3 greatly promoted osteoclast generatio n and subsequent bone resorption, but its presence was not essential f or this process to occur. (C) 1997 Academic Press.