The Effects Of The Different Static Compressive Stress On The Differentiation And Dedifferentiation Of Condylar Chondrocytes Of Neonatal SD Rats In Vitro

[Objective] To investigate the stantant changes of â… , â…¡, â…¢ and PG expression of mandibular condylar chondrocytes(MCCs) stimulated by the different static compressive stresses, so that to make a primary understanding of the relationship between the differentiation and dedifferentiation of condylar chondrocytes and different compressive stresses; to investigate the stantant changes of the content of DNA of mandibular condylar chondrocytes(MCCs) stimulated by the different static compressive stresses, so that to make a primary understanding of the relationship between proliferentiation and apothesis of MCCs and different static compressive stresses.[Materials and Methods] The primary MCC separated from the mandibular condylar cartilage of six neonatal SD rats were cultured and a finite cell line was established in vitro. A static compressive stress with a magnitude of 0Kpa, 12Kpa, 24Kpa, 36Kpa was exerted on the third passage of MCC for 1 hour. On the time points of Oh after the stimulation of stress, the DNA content and cell cycle were evaluated by using flow cytometry, and the expression of collagen type â… , â…¡, â…¢ and PG was detected in the way of in situ immunohistochemical SABC method. [Results] It was found that, except the static compressive stresses with 24Kpa, others, when exerted on the in vitro cultured MCC for 1 hour, had significantly decreased cell proliferation , cell apoptosis and the percentage of the content of DNA of cells in S phase (P<0.05). This effects is most significant for ones with 36Kpa that decrease cell proliferation and the percentage of the content of DNA of cells in S phase and with 12Kpa that decrease cell apoptosis. Besides, 0~ 12~24Kpa, the expression of collagen type â…  and PG is increased.However,24~36Kpa, one is decreased ; 0~ 12~24~36Kpa, one of collagen type â…¡ and â…¢ is increased; [Conclusion] The static compressive stresses with a magnitude with 12Kpa and 24Kpa and duration of 1 hour can promote the activity of the differentiation of cultured MCC in vitro. However, ones with 36 Kpa can result in the dedifferentiation of cultured MCCs in vitro. In addtion, there perhaps is the certain relationship between the cell proliferation and apoptosis and the magnitude of the static compressive stresses.