Osteoinductive molecules in orthopaedics: basic science and preclinical studies.

Osteoinductive molecules are characterized by their ability to promote the formation of bone. Most osteoinductive molecules are cytokines, which are extracellular proteins or peptides that mediate cell to cell signaling. Examples of osteoinductive cytokines are certain bone morphogenetic proteins and some growth and differentiation factors. Some osteoinductive molecules are not secreted molecules. LIM mineralization protein-1 is an example of an intracellular osteoinductive molecule. Significant advances have been made in characterizing the molecular composition and mechanism of action of these osteoinductive molecules. Preclinical studies with these molecules have provided better understanding of the doses, formulation, and delivery mechanism necessary for effective bone formation in model systems of spinal fusion and other orthopaedic problems. The current authors will review the most important basic science and preclinical studies involving these osteoinductive molecules.