In vivo live imaging of bone cells.

There are as many as 200 cell types in the body, and highly sophisticated and varied life phenomena are carried out by cell migration to appropriate places at appropriate times following the appropriate interactions. Recent advances in optical imaging technology using multi-photon excitation microscopy have enabled visualization inside intact bone tissues in living animals without thin sectioning. Using such advanced techniques, the dynamic behaviors of living bone cells on intact bone tissue structures can be elucidated. Here, we focus on recent findings using intravital multi-photon imaging of dynamic biological systems, e.g., bone homeostasis. This novel approach has proven beneficial for understanding the mechanisms underlying the spatiotemporal nature of bone remodeling systems and for evaluating the specific modes of actions of novel drugs currently in development, which will contribute to a new chapter in bone and mineral research.