Flexible polyurethane scaffolds with high biocompatibility for effective chondrogenic performance in cartilage tissue engineering

Cartilage tissue engineering offers a promising solution for addressing severe cartilage damage. To replicate native cartilage properties, scaffolds must exhibit both load-bearing capacity and the ability to regain their original shape. Balancing elasticity and hardness remains a challenge for biomaterials currently used in cartilage tissue engineering. Polyurethane, a Food and Drug Administration-approved elastomeric biomaterial, shows promise in meeting these requirements but shows limited support for cartilage-specific extracellular matrix (ECM) accumulation by chondrocytes. In this study, we employed 3D printing to fabricate multi-layered scaffolds using two modified polyurethane formulations: one combining aromatic polyurethane with cyclic trimethylolpropane formal acrylate to enhance mechanical strength and elasticity, and another incorporating hydroxyethyl methacrylate to improve biocompatibility. These scaffolds supported chondrocyte adhesion and redifferentiation, promoting significant cartilage ECM deposition and the formation of cartilage-like sheets, which not only exhibited cartilage ECM, but also had good elasticity and compressive resistance. These findings highlight the potential of these modified polyurethanes for cartilage tissue engineering and introduce a platform for scaffold-free implantation of engineered cartilage, which could accelerate future clinical applications.