Novel injectable gel (system) as a vehicle for human articular chondrocytes in cartilage tissue regeneration

We developed a novel injectable carrageenan/fibrin/hyaluronic acid-based hydrogel with in situ gelling properties to be seeded with chondrogenic cells and used for cartilage tissue engineering applications. We first analysed the distribution within the hydrogel construct and the phenotype of human articular chondrocytes (HACs) cultured for 3 weeks in vitro. We observed a statistically significant increase in the cell number during the first 2 weeks and maintenance of cell viability throughout the cell culture, together with the deposition/formation of a cartilage-specific extracellular matrix (ECM). Taking advantage of a new in vivo model that allows the integration between newly formed and preexisting cartilage in immunodeficient mice to be investigated, we showed that injectable hydrogel seeded with human articular chondrocytes was able to regenerate and repair an experimentally made lesion in bovine articular cartilage, thus demonstrating the potential of this novel cell delivery system for cartilage tissue engineering.