The Effects Of Compressive Stress On The TGF-β₁ Expression Of Condylar Cartilages In Vitro

[Objective] The purpose of this study was to create the system of organ culture for the condylar cartilage and to investigate the expression change of transforming growth factorβ1 (TCP-Pi) of mandibular condylar chondrocytes during the condylar cartilages were stimulated by compressive stress, and to observe the effect of compressive stress on the TGF-pi expression of condylar cartilages.[Materials and Methods] (1) The mandibular condylar cartilages isolated from 1-day-old SD rats were cultured in a modified Trowell-type culture system for six days and the model of organ culture for mandibular condylar cartilages (MCC) was established in vitro. Every day four cartilages were fixed and embedded in paraffin, sections strained by3eosin and haematine.(2) A static compressive stress with a magnitude of 1 Okpa was exerted on the explants having been cultured for 24hr. On the terminal point of stress stimulation, the expression of TCP-Pi was examined through immunohistochemistry. Meantime, stress-free cartilages were also cultured in the same conditions and tested according to the experiment groups.[Results] Light microscopic observations showed that the mandibular condylar cartilages remained normal during organ culture. Within 4 days, the layers of the cartilage were clear and the structure of the cells of the cartilages were integral and not to collapse. With time lasting, some cells in the part of surface layer collapsed.The expression of TGF-pi on three layers of cartilage, especially maturing chondroblasts layer, had significantly improved when compressive stress was exerted on the cultured cartilages for 1 hour hi vitro.[Conclusion] (1) This system can culture the cartilages successfully for 6 days. Structure and activity of the cartilages cultured for 24 hours remained normal, which were selected for the experiment.(2) The compressive stress with a magnitude of lOkpa for Ihour can improve the expression of all layers of the cartilage. The maturing chondroblasts changed most obviously while the hypertrophic chondrocytes changed lest. It is reasonably concluded that compressive stress can accelerate the proliferation and differentiation of the cells of condylar cartilage.