Collagen-based biomaterials and cartilage engineering. Application to osteochondral defects

Articular cartilage has a limited capacity for self-repair after trauma. Besides the conventional surgical techniques for repairing such defects, treatments involve implantation of autologous cells in suspension or within a variety of cell carrying scaffolds such as hyaluronic acid, alginate, agarose/alginate, fibrin or collagen. For the repair of full-thickness osteochondral defects, tissue engineers started to design single- or bi-phased scaffold constructs often containing hydroxyapatite-collagen composites, usually used as a bone substitute. The purpose of this study was to compare the behavior of bovine chondrocytes cultured in collagen-based scaffolds containing or not hydroxyapatite and cross-linked following two different methods. Calf chondrocytes seeded within Hemotèse and Collapat II sponges (SYMATESE biomaterials), chemically cross-linked with glutaraldehyde or EDC/NHS, were maintained up to one month in culture. The cells exhibited a similar behavior in the four scaffolds regarding proliferation level, deposition of glycosaminoglycans in the scaffolds and gene expression of types I, II and X collagens, aggrecan, MMP-1, -13 and the integrin subunits alpha10 and alpha11.