Changes of distribution of type Ⅵ collagen in osteoarthritis cartilage based on threedimensional images in situ

Objective To explore the changes of spatial distribution of type Ⅵ collagen in osteoarthritis cartilage. Methods Frozen sections of full thick cartilage from osteoarthritis and healthy knee of guinea pig in mode group and control group were performed immunofluorescence staining， and then scanned by Delta-Vision Elite system. The scanning data were processed and analyzed by Imaris software， the volume of chondrocyte （Vc）， thickness and volume of type Ⅵ collagen （Vp） of the two groups were measured. Results In healthy cartilage， every chondrocyte wore a thin coat of type Ⅵ collagen， whose thickness had no significant difference（P＞ 0.05）， and the volume increased （P＜ 0.01） with the increase of depth. In osteoarthritis cartilage， the volume of type Ⅵ collagen coat decreased and distributed irregularly. It showed honeycomb distribution and scattered distribution in transition layer and radiation layer， respectively （P＜ 0.01）. Moreover， the scattered type Ⅵ collagen was found in extracellular matrix. Conclusion The irregular distribution of type Ⅵ collagen in the osteoarthritis cartilage may be one of the factors which induces chondrocyte degeneration.