What initiates the bone remodeling cycle?

The initiation of the bone remodeling cycle is primarily driven by osteocytes. Osteocytes are mature bone cells that originate from osteoblasts. They are strategically located within the mineralized bone matrix and play a pivotal role in maintaining bone homeostasis. When mechanical load or stress is applied to bone tissue, osteocytes can sense these changes and communicate with osteoclasts and osteoblasts to regulate bone remodeling.

Osteocytes release signaling molecules that can either stimulate or inhibit the activity of osteoclasts and osteoblasts, thus playing a crucial role in the coordination of bone resorption and formation. This process ensures that the bone can adapt to mechanical demands and maintain its structural integrity over time.

In contrast, while osteoclasts are responsible for the resorption phase of the bone remodeling cycle and osteoblasts are crucial for the formation of new bone, they act upon signals received rather than initiating the remodeling cycle. Mesenchymal cells are progenitor cells that can differentiate into osteoblasts, but they do not directly start the remodeling process. Therefore, the role of osteocytes in sensing mechanical changes and signaling other cells makes them the primary initiators of the bone remodeling cycle.