Although articular cartilage plays an important role in joint lubrication, it has a limited healing potential due to the lack of vascularity. We have been performing research on cartilage repair by the use of a mesenchymal stem cell-derived tissue engineered construct (TEC). Recently, we developed a novel TEC (gTEC) through a bovine serum-free medium in order to avoid infection due to viral pathogens such as prion protein. The purpose of the present study is to determine the frictional and compressive properties of repaired cartilage treated by gTEC in comparison with that treated by normal TEC. Porcine synovial MSCs were cultured at a high cell density in bovine serum-free medium and extracellular matrix produced by the MSCs were detached from the substratum. The cell-matrix complex spontaneously contracted to develop a gTEC. For compression, a normal TEC was produced in bovine serum medium. The gTEC and TEC were implanted in vivo into chondral defects in the medial femoral condyle of 3-month-old pigs, and repair tissues were obtained after 6 months. Indentation and friction tests were conducted by the use of a friction tester to determine the stiffness and friction coefficient of repaired tissues. Stiffness of gTEC- and TEC-treated cartilage had a tendency to decrease as compared with that of normal cartilage. Coefficient of start-up friction of gTEC- and TEC-treated cartilage were higher than that of normal cartilage, but there was no significant difference between the gTEC-treated and TEC-treated repair tissues. Coefficient of dynamic friction of gTEC- and TEC-treated cartilage were almost identical to that of normal cartilage. gTEC-treated repair cartilage have equivalent frictional and compressive properties with TEC-treated repair cartilage although it is softer than normal cartilage.
