[Expression of beta-catenin in articular cartilage of knee primary osteoarthritis]

To investigate the role of beta-catenin in pathogenesis and progression of knee primary osteoarthritis (OA) by detecting the expression of beta-catenin.

Between October 2010 and May 2011, 40 cartilage specimens were collected from adult knee primary OA patients undergoing total knee arthroplasty and 10 cartilage specimens from adult patients suffering from amputation and femoral condylar fracture. All cartilage samples were taken out from femoral condylar. The decalcified paraffin-embedded sections were prepared and stained with fast green-safranin O to observe the degeneration of cartilage, then the modified Mankin scale was used to classify the degeneration. The expression of beta-catenin was detected by the immunohistochemistry staining and Western blot.

According to the Mankin scale, 10 cases had normal cartilage, 12 had mild degenerative cartilage, and 28 had moderate to severe degenerative cartilage. The histological observation showed the mild degenerative cartilage characterized by fissures in the superficial zone of the articular cartilage, decreased chondrocytes, arrangement disorder, and duplicated tidemark; and the moderate to severe degenerative cartilage characterized by fissures in the deep zone of the articular cartilage, obviously decreased chondrocytes and cluster, and even full-thickness cartilage defect. The beta-catenin did not expressed in normal articular cartilage; but it expressed in the degenerative cartilage, and the expression was significantly higher in the moderate to severe degenerative cartilage than in mild degenerative cartilage (P < 0.05).

Beta-catenin plays a significant role in the pathogenesis and progression of knee primary OA, and the mechanism may be the activation of Wnt/beta-catenin signaling pathway, which promotes transcription of inflammatory genes and leads to the destruction of articular cartilage.