Physical environments play important roles for maturation of mechanical functions of tissue. In this study, effects of relative tribological movement on the expression of tribological function of regenerated synovial membrane were investigated. Fibroin sponge derived from silk was used as a three-dimension scaffold for the synovial membrane regeneration. Synovial cells were isolated from human synovial membrane, and were seeded onto the fibroin sponge. Magnetic stirring system (named Stirring Chamber) was used for culturing with relative slip motion where the cell-seeded side of the scaffold had been rubbed by a glass culture dish for 24 hours/day.

Histological view of regenerated tissue of the dynamically cultured group (D group) showed extracellular-matrix-like eosinophilic meshwork structure formed continuously on the meshwork structure of the fibroin sponge. The newly formed tissue showed expression of collagen type I, especially on the surface of fibroin sponge. These structures were not seen in the statically incubated group (S group). Each group didn’t show expression of collagen type II.

Frictional force was measured by using leaf spring method under the conditions of the sliding velocity: 0.8 mm/s, the loading time prior to sliding: 1 minute, and the applied load during the experiment: 0.029 N. The counterface for regenerated synovium was a flat stainless steel of which roughness was 0.06 μm Ra. All frictional experiments were performed in the saline solution and at room temperature (25°C). The friction coefficient of tissues cultured statically was 0.6–0.8, and that of tissues cultured with sliding motion was 0.2–0.4 at one week culturing, 0.3–0.5 at two weeks culturing.

Our previous experiment showed that combination of fibroin-sponge scaffold and Stirring-chamber culturing system improved the tribological performance of regenerated cartilage tissue. The present study suggests that this combination have also a possibility for synovial cells to form functional lubricious membrane which can be used as anti-adhesion membrane for knee, ligament, and/or other surgical procedures. However, the deterioration of lubrication properties in the 2 weeks dynamically cultured group would indicate that the too long continuous tribological movement does not provide an optimal condition. More fine tribological loading history should be designed.