Many researchers tried to improve mechanical properties of the cultured cartilage by physical stimulation. However, its mechanical properties were insufficient. Extracellular matrix structure similar to natural articular cartilage is necessary to form mechanical properties of cultured cartilage. Gradient magnetic field was expected to change pericellular microenvironment associated with local chondrocyte activity. We investigated the effects of gradient magnetic field on chondrocyte activity and extracellular matrix structure.
Chondrocytes were cultured under the gradient magnetic field for 7 days, and stimulation time was 12 hours in a day. Intensity of magnetic field was 1.5 mT in the center of a dish. Intensity of gradient magnetic field was 0.03 mT/mm. Chondrocytes were cultured under the uniform magnetic field for control group. The synthesized extracellular matrix in a dish was observed with second harmonic generation, and GAG amount was measured after cultivation.
GAG amount in the gradient group was almost same with that in the uniform group. According to SHG image, the area and the thickness of extracellular matrix increased with increasing intensity of magnetic field in the gradient group. This study showed that the gradient magnetic field stimulation formed difference in extracellular matrix structure which depends on local chondrocyte activity.