Bone repair and regeneration

Bone tissue has remarkable repair capacity, and generally heals by regeneration. This unique potential, expressed during remodelling and bone fracture healing, is tuned by a complex interplay of active factors and responding cells, which resides on an informative extracellular matrix and acts under a strict genetic control and different mechanical stimuli. The coordinated interaction of these elements is increasingly understood thanks to progress in cellular and molecular biology. This chapter deals with the sequential events leading to bone repair, with special attention given to the role of mesenchymal stem cells in regenerating bone. The genetic control of bone healing, the pathways underlying such process and the regulation by a variety of growth factors and cytokines are outlined according to the recent literature. Understanding the key elements of bone regeneration and their cross-talk is not merely a theoretical advancement in the knowledge of the physiological turnover of bone tissue, but offers practical tools for increasing the efficacy of orthopaedic procedures, such as the delivery of pro-osteogenic growth factors or mesenchymal stem cells.