Degree of endplate chondrocyte degeneration in different tension regions during mechanical stimulation

The aim of this study was to explore the degree of degeneration of endplate chondrocytes in different tension regions induced by intermittent cyclic mechanical tension (ICMT) in vitro. Rat endplate chondrocytes were harvested and treated with 10% ICMT for 8 h/day with a frequency of 0.5 Hz. A cartilage degeneration model was induced using an FX-5000T cell strain-loading system. The experiment was divided into the central region and the peripheral region, according to the contact area between the loading post and the six-well flexible silicone rubber BioFlex plates. Toluidine blue and phalloidin staining were used to observe the morphological changes of cells following mechanical stimulation. Apoptosis was detected by flow cytometry and the mRNA and protein expression levels of collagen type II 1, aggrecan, SRY-box 9 and matrix metalloproteinase 13 were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blotting, respectively. Endplate chondrocytes exhibited degenerative alterations under mechanical conditions of 10% ICMT and 0.5 Hz at 8 h/day. Toluidine blue and phalloidin staining demonstrated that the cells in the peripheral region were more slender compared with cells in the central region, but RT-qPCR and western blotting results demonstrated that the degree of cell degeneration between the two groups was not statistically differences. So that cell morphological alteration does not imply that cells have undergone degeneration.