Objective: We investigated the characteristics of cell morphology and expression of types I, II, III, and X collagen and matrix metalloproteinase-13 (MMP-13) of chondrocytes from articular cartilage of adult patients with Kashin-Beck Disease (KBD) in vitro to understand the pathogenesis in chondrocytes.
Methods: Samples of articular cartilage were divided into 2 groups: KBD group (8 samples, 8 cases) and the control (8 samples, 8 cases). KBD patients were diagnosed according to "Pathological Criteria to Diagnose KBD in China." Hyaline cartilage was digested with collagenase into cell suspensions and cultured in monolayers. Chondrocyte ultrastructure was observed by electron microscope at 10th day in vitro. Primary articular chondrocytes were seeded on microscope slides and immunostained on 12th day of cultivation for types I, II, III, and X collagens and MMP-13. Positive findings were counted by light microscopy and confirmed by flow cytometric analyses.
Results: Considerable amounts of vacuoles and distorted nuclei, as well as thickening and irregular arrangement of collagen fibrils, were seen in the KBD samples by electron microscopy. Types I, III, and X collagen were stained in the KBD, but not in the control cultures. The percentages of positive staining for type II collagen were significantly lower in KBD than those in controls (t col II = -5.54, p < 0.001), and for MMP-13 in the KBD group were significantly higher (t MMP-13 = 3.70, p < 0.01).
Conclusion: Phenotype expressions of types I, II, III, and X collagen and MMP-13 in chondrocytes cultured in vitro were significantly different between the KBD and control cultures, indicating degenerative and hypertrophic changes in chondrocytes of KBD articular cartilage.