Following injury, articular cartilage may fail to repair or may repair by fibrocartilage, resulting in impaired clinical function and loss of biochemical and biomechanical characteristics. A group of new biomaterials, made from collagen, hyaluronic acid, and hydroxylapatite, have been developed to immobilize chondrocytes in vitro and support subsequent cell growth. These collagen/chondrocyte tissue analogues formed in culture are placed into surgically induced cartilage defects to facilitate the repair of articular cartilage. Phase I in vitro studies were used to determine the optimal pore size of the collagen matrix and hyaluronic acid concentration of the composite material, as determined by chondrocyte growth. In addition, a preliminary in vivo study with rabbits investigated the histology and mechanical properties of surgically damaged hyaline cartilage (defects through the subchondral plate) with and without the cartilage repair material. It was shown that the material provided a strong framework for the repair of hyaline cartilage. The Phase II proposal intends to optimize the composition parameters of the material, and complete a series of animal studies that will lead to human clinical trials.
