The Study Of The MMP-1,ALP And VEGF Expression In Human Periodontal Ligament Fibroblasts Under Mechanical Stress In Vitro

[Objective]To culture the human periodontal ligament fibroblasts (hPDLFs) in vitro. To investigate the differential effects on the expression of matrix metalloproteinase-1 (MMP-1), alkaline phosphatase (ALP) and vascular endothelial growth factor (VEGF) in hPDLFs caused by different dynamic mechanical stress in vitro. The aim of this study is to further investigate the biomechanical process within the tissue remodeling during orthodontic tooth movement.[Methods]The hPDLFs were cultured using the method of improved tissue adhering and were identified by their morphological and using immunochemistry. Dynamic mechanical compressive and tensile stress were applied in vitro to the hPDLFs with the use of a four-point bending system with 5000μstrain, at a frequency of 0.5Hz, for 0,2,6 and 12 hours respectively. The expression of extracellular matrix remodeling associated molecules MMP-1, ALP and VEGF were analyzed by indirect immunofluorescence (IIF) and/or western blot (WB).[Results]Using the method of improved tissue adhering, we have successfully cultured and subcultured the human periodontal ligament (PDL) cells. The cultured cells showed typical characteristics of hPDLFs. In the present study we showed by IIF and/or WB that the common hPDLFs expressed MMP-1, ALP and VEGF. Dynamic compressive stress down-regulated the amount of ALP at 2 hours, while up-regulated the amount of MMP-1 at 6 hours. Dynamic tensile stress down-regulated the amount of ALP at 6 hours, while up-regulated the amount of MMP-1 at 2 hours. Both dynamic compressive and tensile stress down-regulated the amount of VEGF, while the amount of VEGF recovered to the control level under tensile stress at 12 hours.[Conclusions]We have cultured the hPDLFs successfully. Stress and time-dependent mechano-transduction in hPDLFs involves activity of MMP-1, ALP and VEGF. MMP-1 and ALP may take part in the process within the tissue remodeling during orthodontic tooth movement as correlation factors. The hPDLFs may adapt to dynamic tensile stress earlier and recover the expression of VEGF to accelerate the tissue remodeling.