Bone Imaging: Osteoclast and Osteoblast Dynamics.

Bone is continually remodeled by bone-resorbing osteoclasts and bone-forming osteoblasts. Although it has long been believed that bone homeostasis is tightly regulated by communication between osteoclasts and osteoblasts, the fundamental process and dynamics have remained elusive. To resolve this, we established an intravital bone imaging system using multiphoton microscopy to visualize mature osteoclasts and osteoblasts in living bone.We herein describe the methodology for visualizing the in vivo behavior of bone-resorbing osteoclasts and bone-forming osteoblasts in living bone tissues using intravital multiphoton microscopy. This approach facilitates investigation of cellular dynamics in the pathogenesis of bone-destructive disorders, such as osteoporosis and rheumatoid arthritis in vivo, and would thus be useful for evaluating the efficacy of novel anti-bone-resorptive drugs.