Growth Factors and Bone Remodeling

Overview

There are two essential processes necessary for proper growth and maintenance of bone mass. These are boneresorption and bone formation. During childhood and adolescence, the bone formation exceeds bone resorption,in adults both processes are balanced, and during aging, resorption exceeds formation. Growth factors play anessential role in the coupling of bone formation to bone resorption. Bone matrix contains growth factors, producedby osteoblasts. In the process of bone resorption, the growth factors are released from the matrix and fromosteoclasts. Thus, the growth factors released during bone resorption act as paracrine agents on stromal cellsthereby generating more bone forming cells in proportion to the amount of bone resorbed. The amount of newlyformed bone is not only determined by the amount of growth factors released from matrix during resorption, butalso by the growth factors produced by both osteoblasts and osteoclasts. Some metabolic bone disorders resultfrom the uncoupling of bone formation to bone resorption. The reduction of growth factors thus plays an importantrole in the pathogenesis of metabolic bone diseases.

Key words:
growth factors, bone resorption, bone formation