Cellules osseuses et remodelage osseux.

Abstract

Recent data have shown that bone remodeling is a complex process, involving multiple components. These include cells of various origin, a calcified extracellular matrix and numerous factors regulating cellular activities, tissue formation and degradation. Bone resorption and formation activities are regulated at various levels during the course of bone cell differentiation. These activities are ensured by various hormones, many of them having indirect effects on bone cells through the production of local factors. Various cytokines and growth factors have been shown to affect bone cells proliferation and differentiation and these effects are modulated by many hormones. Cells of the osteoblastic lineage may play an important role in the regulation of bone remodeling as they synthesize a number of local factors affecting osteoclasts. These cells are also involved in the first steps of matrix degradation, allowing thus osteoclast attachment to the bone matrix. Some local growth factors are incorporated into the bone matrix and may serve as coupling agents between bone resorption and formation. The precise contribution of these factors during the process of bone remodeling in normal conditions and ageing is, however, unclear.