Collagens of articular cartilage: structure, function, and importance in tissue engineering.

Collagen is a crucial matrix component of articular cartilage. Because articular cartilage is a load bearing tissue, developing mechanical integrity is a central goal of tissue engineering. The significant role of collagen in cartilage biomechanics necessitates creating a collagen network in tissue engineered constructs. An extensive network of collagen fibrils provides cartilage with mechanical integrity, but developing strategies to replicate this collagen network remains a challenge for articular cartilage tissue engineering efforts. To study the structure and biomechanics of the collagen network, many experimental and computational methodologies have been developed. However, despite extensive cartilage tissue engineering research, few studies have assessed collagen type, crosslinks, or fibril orientation. Further study of the collagen network, both within native tissue and engineered neotissue, will enable more robust constructs to be developed. This review focuses on the biology and biomechanics of the collagen network, relevant experimental methods for assessing the collagen network, and articular cartilage tissue engineering studies that have examined collagen.