Osteoblast biology: developmental origin and interactive nature of osteoblasts

Abstract Bone formation occurs throughout life to support growth and bone remodeling in response to mechanical forces, metabolic needs, and tissue repair upon injury. The physiological requirement for continuous bone renewal to accommodate remodeling necessitates recruitment, proliferation, and differentiation of bone-forming osteoblasts to counteract the activity of bone-resorbing osteoclasts. Numerous developmental regulatory pathways control transcriptional and posttranscriptional epigenetic mechanisms during multiple stages of osteoblast growth and differentiation. These mechanisms modulate expression of genes associated with the biosynthesis, organization, and mineralization of the bone extracellular matrix, as well as metabolic responses. This chapter focuses on the molecular phenotype and physiological functions of osteoblasts in bone formation and bone homeostasis. Our understanding of the molecular mechanisms that control osteoblast lineage progression permits consideration of new therapies for stimulating bone formation in the aging skeleton, fracture repair, pathologies of metabolic bone diseases, and orthopedic implant stability.