OSTEOGENIC AND OSTEOCLASTIC CELL-INTERACTION - DEVELOPMENT OF A COCULTURE SYSTEM

The processes involved in the regulation of bone cell metabolism are c omplex, including those implicated in bone cell coupling. This study w as undertaken to develop a model that would permit real-time interacti on between osteoclastic cells and osteoblasts in vitro. Osteogenic bon e marrow stromal cells were isolated from 18-day-old embryonic chicken s, while osteoclastic cells were isolated from laying White Leghorn he ns on calcium-deficient diets. Osteoclastic cells (5 x 10(5)) were see ded onto mineral thin films and suspended above osteogenic cells (1 x 10(4)) already plated on the bottoms of tissue culture plate wells. Th e data showed that after 4 days of incubation there was up to a fivefo ld (P < 0.05) reduction in all measured parameters of osteogenesis (mi neralization, alkaline phosphatase activity and type I collagen produc tion) in osteogenic cultures grown in the presence of osteoclastic cel ls. Similarly, osteoclastic cell-induced mineral resorption was reduce d up to threefold (P < 0.05), Go-culture effects on cellular responses could be manipulated by known antiresorptive agents (e.g., pamidronat e) altering either the source or the age of osteoclastic cells. The re sults indicate that the co-culture model may be useful in the study of bone cell interactions.