二電極電気インピーダンス法による軟骨細胞—アガロース複合体の評価

抄録

Since articular cartilage has important mechanical functions, it is important to evaluate the mechanical properties of cultured cartilage in terms of whether those properties are the same as those of natural cartilage. Mechanical tests such as a compression test and a dynamic visco-elastic measurement are useful for measuring mechanical properties of cultured cartilage, but these methods may damage cultured cartilage. Therefore, there is a need to develop an evaluation method to measure the mechanical properties of cultured cartilage without damaging the tissue. The purpose of this study was to evaluate the electrical impedance of cultured cartilage using a two-electrode electrical impedance method during cultivation. Chondrocytes were isolated from the distal femur of 6-month-old pigs. Chondrocytes were embedded in agarose gel (6 mm in diameter, 1.5±0.2 mm in thickness) at a cell concentration of 5.0×10⁶ cells/ml. Electrical impedance measurement, compression test, biochemical analysis and histological observation were carried out before cultivation and after 4, 8, 12 and 16 days of cultivation. The electrical impedance at 5.0×10⁴ Hz measured using a two-electrode electrical impedance method was defined as a passive electrical property of chondrocyte-agarose construct. Compressive stiffness of chondrocyte-agarose construct was calculated from stress-strain curve obtained from compression test. Synthesis of extracellular matrix was observed after 8 days of cultivation, and the amount of glycosaminoglycan increased with cultivation days. The electrical resistivity increased with cultivation days, and it showed a significant correlation with the amount of glycosaminoglycan. The compressive stiffness also increased with cultivation days, and it was significantly correlated with the amount of glycosaminoglycan. The electrical resistivity of chondrocyte-agarose construct was found to be significantly linearly correlated with the compressive stiffness. These results showed that the compressive stiffness of chondrocyte-agarose construct can be estimated by measuring its electrical impedance during cultivation.