Bone

Bone is a specialized mineralized connective tissue composed of a dense extracellular matrix predominantly consisting of type I collagen and hydroxyapatite crystals, which together provide mechanical strength and rigidity[1][3][7]. It contains four main cell types: osteoblasts (bone-forming), osteocytes (mature, matrix-embedded), osteoclasts (bone-resorbing), and bone lining cells, all coordinating bone remodeling and homeostasis[1][7]. Bone serves structural, protective, metabolic, and hematopoietic functions, and its dynamic remodeling is tightly regulated by local and systemic factors, including various hormones, cytokines, and growth factors[1][7][9]. In clinical medicine, bone is a tissue system rather than a molecular or protein target; therapies for bone diseases commonly target molecular mediators (such as RANKL, parathyroid hormone receptor, sclerostin) or pathways involved in bone cell activity and matrix regulation, rather than "bone" as a discrete target in the sense of a single molecular entity[2][4].

Other names

Bone tissueOsseous tissue

Bisphosphonates: Inhibit osteoclast-mediated bone resorption Denosumab: RANKL inhibitor, reduces osteoclast formation/function Parathyroid hormone analogs: Intermittent stimulation of bone formation (anabolic effect) Romosozumab: Sclerostin inhibitor, increases bone formation and reduces resorption Calcitonin: Directly inhibits osteoclast activity