Reaction and changes of rabbit mandibular condyle cultured in vitro to mechanical compression
2022, 20 (4):
PURPOSE: To investigate the changes of rabbit mandibular condyle under mechanical compression in vitro. METHODS: Mandibular condylar explants were cultured in vitro, and subjected to static pressures of 0(control), 15 and 75 kPa for 3 days, respectively. The gross morphology, histology and expression of collagen II(COL2), collagen X (COL10), SOX9 and MMP13 were examined, and micro-CT was performed. Statistical analysis was carried out using SPSS 16.0 software package. RESULTS: In 15 kPa group, the condyle was still intact and white with flat remodeled articular surface. In 75 kPa group, the remodeled articular surface was rough, and flat area was larger than that in 15 kPa group. Condyles became dulling and yellow with cracked cartilage in the center of articular surface. The morphological structure of the condylar cartilage and chondrocytes were more compacted than those in the control group. In the 75 kPa group, the whole layer of cartilage was damaged and detached from the subchondral bone in the central area. The expression of COL2 and SOX9 increased significantly under the pressure of 15 kPa (P<0.01), and decreased significantly at 75 kPa. The expression of COL10 and MMP13 increased significantly under the pressure of 75 kPa(P<0.01). Micro-CT showed a significant increase in bone mineral density(BMD), bone volume/total volume(BV/TV) and trabecular thickness(Tb.Th) in the pressurized groups(P<0.01). CONCLUSIONS: The integrity and function of condylar explants were maintained under the mechanical loading of 15 kPa, and adaptive remodeling was observed. Degenerative changes in cartilage were observed at 75 kPa. The pressure of 75 kPa exceeded the junction bond of cartilage and subchondral bone, and resulted in detachment of cartilage from subchondral bone which may lead to osteoarthritis.
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