Stromal cells obtained from the synovial membrane of porcine knee joints were cultured in DMEM in monolayer in the presence of ascorbic acid 2-phosphate. In seven days, the monolayer cell/matrix complex was detached from the culture dish to allow active contraction of the cell/matrix complex for 8 hours, for the development of a 3-D bioengineered tissue (3DBT). A round-shaped chondral defect of 8mm in diameter and 1.5mm in depth was created on the medial condyle of the porcine femur. The defect was filled with the 3DBT, and the porcine was allowed cage activity. Six months after the surgery, a cylindrically shaped cartilage-subchondral bone specimen of 4mm in diameter and 5-8mm in depth was extracted and subjected to quasi-static and dynamic compression tests as well as reciprocal friction test. In quasi-static compression test, a rate-dependency was observed in the repaired tissue with 3DBT in the same way observed in normal cartilage; the tangent modulus was higher with the increase of elongation rate. In contrast, no rate-dependency was observed in the tissue in the untreated defect. In dynamic compression test, the strain of the repaired tissue without 3DBT continuously increased as time passed, and did not reach to equilibrium. In contrast, the strain of the repaired tissue with 3DBT kept the same level as that of normal cartilage. In friction test, the coefficient of friction of the repaired tissue with the 3DBT against glass plates was similar level to that of normal cartilage. These results suggested that compressive and frictional properties of the cartilage regenerated by the use of 3DBT were restored, except for dynamic compressive property.
