BACKGROUND: Previous studies have confirmed that in the animal models of articular cartilage defects and osteoarthritis, the chondrocytes can overexpress the matrix metalloproteinases. Various abnormal stimuli are likely to break the balance between matrix metalloproteinase and tissue inhibitor of metalloproteinase, thus leading to degeneration of extracellular matrix of articular cartilage, as well as the decline and offset of cartilage chondrocytes.
OBJECTIVE: To observe the effect of cyclic tensile strain on the expression of matrix metalloproteinases during the repairing process of rabbit articular cartilage defects.
METHODS: The animal models of articular cartilage defects were established, and chondrocytes were separated for culture at 10 weeks after operation. The chondrocytes on the non-surgical side were considered as the normal group, and the chondrocytes on the surgical side were randomly divided into high cyclic tensile strain group, low cyclic tensile strains group and control group, and the load amplitude was sin10%. Then 0.1, 1.0 and 0 Hz cyclic tensile strains were loaded respectively. The expressions of matrix metalloproteinases 2, 3, 9 and 13 in each group were detected with reverse transcription-PCR at 24, 48 hours, 1, 2 and 4 weeks after loading cyclic tensile strain.
RESULTS AND CONCLUSION: There were significant differences in the expressions of matrix metalloproteinases 2, 3, 9 and 13 at 24 hours after loading cyclic tensile strain between the normal group and the control group (P < 0.05); and there were significant differences in the expressions between the high cyclic tensile strain group and the low cyclic tensile strain group at 1, 2 and 4 weeks after loading cyclic tensile strain (P < 0.05). At the same time, the expressions of matrix metalloproteinases 2, 3, 9 and 13 in the low cyclic tensile strain group were continued to decline, and there were significant differences in the expressions after loading cyclic tensile strain for 24 hours and 4 weeks (P < 0.05). The results indicate that mechanical load can affect the expression of matrix metalloproteinases in the healing process of rabbit articular cartilage defects. In the cellular and molecular level, the incidence and development of pathological articular cartilage defect and stress should affect each other.