Effect Of Cyclic Tensile Stress On Cells Proliferation And Expression Of CTGF In Human Periodontal Ligament Fibroblast And Its Mediated Pathway

Objective:To observe the effect of cyclic tensile stress on cells proliferation and expression of CTGF in the hPDLFs by imposing cyclic tensile stress on hPDLFs in vitro at different times with multi-channel cell stretch stress loading system; To clarify the role of JNK, p38MAPK, PI3K pathway in the cyclic tensile stress induced expression of CTGF in hPDLFs by using specific inhibitors of JNK,p38and PI3K.Methods:1. An in vitro culture-tensile stimulate models of hPDLFs were established by using a multi-channel cell stretch stress loading system. Cell morphology was observed and the growth curve was drawn, to prepare the experiment cells for mechanical loading experiments.2. The cells of stress application group were given stimulation of cyclic tensile stress for1h,6h,12h,24h. The loading extent was set for10%(each cycle included3s-stretch/3s-relaxation), with frequency of0.1Hz (6cycles/min). The control group was not given any stimulation as the same time. The cells proliferation was determined byCCK-8assay (Cell Counting Kit-8). The concentrations of CTGF in the culture supernatant were measured by commercially available enzyme linked immunosorent assay(ELISA) kits according to manufacturer’s instructions. The expression of CTGF mRNA was detected by real-time RT-PCR.3. The cells of stress application for12h were given SP600125, SB203580and LY294002, the specific inhibitors of JNK, p38MAPK, PI3K respectively at the beginning, the CTGF expression of which was compared with the groups of none inhibitors.Results:1. The hPDLFs proliferated typically and stably in vitro, and could be be given cyclic tensile stress.2. Compared with the control group, hPDLFs of stress application groups began to proliferate at1h, and proliferated manifestly at6h, and proliferation reached the peak at12h, then proliferation decreased at24h. Similarly, the expression of CTGF began to increase at1h, and increased manifestly at6h, and reached the peak at12h, then decreased at24h. 3. The expression of CTGF reduced by using the specific inhibitors of JNK, while the specific inhibitors of p38MAPK, PI3K had not the same effect.Conclusion:1. Cyclic tensile stress with extent of10%and frequency of0.1Hz can induce hPDLFs proliferation and CTGF expression.2. In a certain time, cyclic tensile stress can induce a time-dependent increase in CTGF mRNA and protein levels. Along with the extending of time, CTGF expression decreases.3. Cyclic tensile stress-inducible expression of CTGF in hPDLFs is mediated by JNK pathway.