抄録
Articular cartilage, which has no nerves and veins and needs less nutrition and oxygen than other cells, has been expected to be able to be reconstructed in vitro. However the method of regenerating articular cartilage has not been established yet. One of the promising methods for regenerating cartilage tissues is to culture those under mechanical stimulation such as compressive stress, hydrostatic pressure by simulating physical conditions in vivo. However, it is still unknown how chondrocytes sense such mechanical stimulations under physiological conditions. Therefore, it is needed to make clear the micro biomechanics of cartilage tissues in vivo and mechanosensitivity of chondrocytes in situ in order to make regenerative cartilage tissues more similar to native cartilage tissues. In this research, we measured the static mechanical properties of articular cartilage tissues, the dynamic mechanical properties through compressive stress loading, and the number of cells that change their intracellular Ca ion concentrations. The results in static tests showed that each tissue layer has different cell density and volume and surface ratio of each single cell. The results in dynamic tests showed that the time change of strains in the top layer is larger than that in the middle and bottom layer, and the constants of the model formula of articular cartilage tissues are different among layers. The results in measuring the number of cells that change their intracellular Ca ion concentrations, showed that the change in Ca ion concentrations was found in the middle and bottom layer but not in the top layer. Moreover, it is also found that there is a relationship between the change in Ca ion concentrations and the initial strains and the final strains calculated by the model formula of articular cartilage tissues.
