Repair of articular cartilage defects using bilayered scaffolds is problematic because tissue-engineered cartilage is prone to overgrowth toward subchondral bone, resulting in structural abnormalities of cartilage and subchondral bone. A "twice freeze-drying" technique was used to construct a dense isolation layer between the cartilage and subchondral bone layers in an integrated bilayered scaffold to prevent cartilage from excessive downgrowth. Briefly, beta-tricalcium phosphate was used for the subchondral bone layer of the scaffold, high-concentration chitosan/gelatin solution for the dense isolation layer, and low-concentration chitosan/gelatin solution for the cartilage layer. As controls, cell-free trilayered scaffolds, autologous osteochondral transplantation, and the bilayered scaffolds were used for repair of osteochondral defects. After 6 months, two of the eight goats in the bilayered scaffold group showed conspicuous cartilage downgrowth, whereas no excessive downgrowth of cartilage was observed in the trilayered scaffold group. Moreover, there was no difference in the repair efficacy between the trilayered scaffold and mosaicplasty group. The results confirmed that the trilayered scaffold effectively prevented cartilage downgrowth with better cartilage repair.
Keywords: biomimic; monolithic; osteochondral defects; tissue engineering; trilayered scaffold.