Abstract:

BACKGROUND: Previously studies demonstrated that matrix metalloproteinase (MMP) and collagen participate in physiological restitution and pathological damage of articular cartilages.
OBJECTIVE: To explore the expressions of MMP and collagen in cartilage tissues in knee articular cartilages defects and surface defects models.
METHODS: Forty-eight SD female rats were used in this experiment. These rats were randomly divided into three groups. Group A (full-thickness defect group): a full-thickness cylindrical osteochondral defect was created in both condyles of femur. Group B (surface cartilage defect group): several partial-thickness articular cartilage defects in both condyles of femur. Group C (control group) was the opposite as shum-perative control. The rats were sacrificed at 4, 8, and 12 weeks. The expressions of collagen Ⅰ, collagen Ⅱ, and MMP-3 in each group were evaluated by hematoxylin-eosin staining and immunohistochemical analyses.
RESULTS AND CONCLUSION: In group A, a small amount of new organization generated at 4 weeks after operation; the defects were filled with fibrous tissues at 8 and 12 weeks after operation; Type Ⅰ collagen was positive expressed, type Ⅱ collagen negative expressed and MMP-3 expression increased. In group B, no signs of repair were found at 4 and 8 weeks after operation; the defects were filled with small volume of fibrous tissues, in which type Ⅰ collagen was positive while type Ⅱ collagen was negative; MMP-3 expression were increased. In group C, the articular cartilages were normal, type Ⅰ collagen was negative, type Ⅱ collagen was positive, and MMP-3 expression was low expressed; no morphological abnormal change could be seen. Mechanical injury can make articular cartilage extracellular matrix composition changed and loss of their original biological characteristics. MMP-3 expression in injured cartilage tissues is increased that leads to high matrix degradation. Thus, MMP-3 is an important factor for articular cartilage degeneration.