Abstract:

Objective　The purpose of this studywas to investigate effects of static tension-stress andTGF-β1on proliferation of mandibular condylar chondrocytes in vitro.Methods　The fourth-passage chondrocytes were harvested from the mandibular con- dyles of 2-week-old SD rats for this study, and a cellular static tension-stress device was used to apply stress on cells. The effects of continuous static tension-stress and/or transforming growth factor-β1(TGF-β1) on the proliferation of mandibular condylar chondrocytes were examined using flow cytometry. The experimentwas divided into two parts. The first part consisted of 100 specimenswhichwere divided into 20 groupswith differentTGF-β1dosage (0 ng/ml, 0.1 ng/ml, 1 ng/ml and 10 ng/ml) for 0, 6, 12, 18 and 24 hours re- spectively. The second part consisted of 30 specimens which were divided into six groups under continuous static tension-stress (5 kPa) and different TGF-β1doseage (0.1 ng/ml, 1 ng/ml, 10 ng/ml) for 0, 6 and 12 hours. Multivariable analyses were conducted to test for associations between proliferation of mandibular condylar chondrocytes and TGF-β1and/or different stresses.Results　The results showed that TGF-β1had a mitogenic effect on rat mandibular condyle at the concentrations of 0.1, 1 and 10 ng/ml, and the mitogenic effects of TGF-β1on condylar chondrocytes were demonstrated in 12 to 18 hours after application of stresses, and the peak of mitogenic effects appeared at 18 hour (P<0.05). The most active mitogenesis happened in the group with continuous static ten- sion-stress (5 kPa) combined with TGF-β1.Conclusion　These results prove mechanical stimulates and TGF-β1in vitro could influ- ence and regulate the growth of condylar chondrocytes.

Key words: static tension-stress, transforming growth factor-β1, mandibular condylar chondrocytes, proliferation, functional orthopedics