OSTEOCLASTS, MACROPHAGES, AND THE MOLECULAR MECHANISMS OF BONE-RESORPTION

The osteoclast is a physiological polykaryon and the major if not excl usive resorptive cell of bone. It participates in bone remodeling, rep air, and growth and mobilization of mineral to meet homeostatic demand s. Most importantly, osteoporosis, a disease endemic in Western societ y and Asia, is always a reflection of enhanced osteoclastic activity r elative to bone formation by osteoblasts. In fact, all forms of anti-o steoporosis therapy proven successful involve inhibition of osteoclast ic bone resorption. Bone resorption is regulated either by altering re cruitment of osteoclast precursors into fully differentiated resorptiv e polykaryons or modulating the rate at which mature osteoclasts degra de bone. With this in mind, our laboratory has focused on the molecula r mechanisms of osteoclast differentiation and the means by which the cell degrades bone matrix.