A self-assembling process in articular cartilage tissue engineering

Current therapies for articular cartilage defects often result in fibrocartilaginous tissue. To achieve regeneration with hyaline articular cartilage, tissue-engineering approaches employing cell-seeded scaffolds have been investigated. However, limitations of scaffolds include phenotypic alteration of cells, stress-shielding, hindrance of neotissue organization, and degradation product toxicity. This study employs a self-assembling process to produce tissue-engineered constructs over agarose in vitro without using a scaffold. Compared to past studies using various meshes and gels as scaffolding materials, the self-assembly method yielded constructs with comparable GAG and collagen content. By 12 weeks, the self-assembling process resulted in tissue-engineered constructs that were hyaline-like in appearance with histological, biochemical, and biomechanical properties approaching those of native articular cartilage. Overall, constructs contained two thirds more GAG per dry weight than calf articular cartilage. Collagen per dry weight reached more than one third the level of native tissue. IHC and gel electrophoresis showed collagen type II production and absence of collagen type I. More importantly, self-assembled constructs reached well over one third the stiffness of native tissue.