Collagens--major component of the physiological cartilage matrix, major target of cartilage degeneration, major tool in cartilage repair.

Collagens serve important mechanical functions throughout the body and in particular in the connective tissues. Additionally, collagens exert important functions as cellular microenvironment and partly via binding and release of cellular growth mediators. In articular cartilage, fibrillar collagens are providing most of the biomechanical properties of the extracellular matrix essential for its functioning. The collagenous matrix is one main target of destructive processes in general degenerative joint disease and focal matrix lesions. The development of an adequate collagen framework represents the major aim of therapeutic cartilage repair. In this respect, collagenous matrices or collagen-imitating scaffolds are more and more emerging as highly suitable vehicles for cell and (growth) factor transport into cartilage lesion. Thus, collagens are not only major constituents of connective tissues in terms of integrity and function, they are also major targets of tissue destruction and regeneration and might become major tools to achieve tissue repair.