A biomechanical analysis of an engineered cell-scaffold implant for cartilage repair

This study evaluated the biomechanical and physical properties of newly formed cartilage engineered from isolated chondrocytes in combination with matrix components. Four groups of constructs were studied. Group A consisted of lyophilized articular cartilage chips mixed with a cell-fibrinogen solution and thrombin to obtain constructs made of fibrin glue, chondrocytes, and cartilage chips. Group B constructs were prepared using fibrin glue and cartilage chips without cells. Group C contained chondrocytes in fibrin glue without chips, and group D comprised constructs of fibrin glue alone. Specimens were implanted in the subcutaneous tissue of nude mice for 9 weeks. At necropsy the specimens were examined grossly, physically, biomechanically, and histologically. The original, preimplantation mass of the constructs was retained only in experimental group A. Histological analysis of specimens in experimental groups A and C demonstrated the presence of newly formed cartilaginous matrix, whereas only fibrotic tissue was observed in control groups B and D. Biomechanical analysis demonstrated higher mean values of equilibrium modulus in the experimental samples of group A with respect to all control groups. This study demonstrated that adding lyophilized cartilage chips to a fibrin glue-engineered cartilage construct maintains the biomechanical properties and the original mass after medium-/long-term in vivo transplantation.