Abstract: Objective　To investigate the effect of different magnitudes of SMS on the inflammatory cytokines reactions of HPDLSCs and PPDLSCs. Methods　In vitro culture-tensile stimulation models of HPDLSCs and PPDLSCs were established using a Flexcell Tension Unit. SMS was applied on the HPDLSCs and PPDLSCs (the load was set for 6%, 8%, 10%, 12%, 14%, with frequency of 0.1 Hz.) for 12hours. At the same time，the normal control group was established. The secretions of inflammatory cytokines IL-6，IL-8，IL-1β and TNF-α were examined by elisa. Results　The secretion of IL-6, IL-8, IL-1β and TNF-α were higher in PPDLSCs than in HPDLSCs without SMS(P<0.05). When SMS was loaded, the expressions of IL-1β and TNF-α increased a little in PPDLSCs(P<0.05). However, the expression of IL-6 and IL-8 was up regulated to a considerable high level and had a positive correlation with the magnitude of SMS in a certain range in PPDLSCs. Conclusions　The periodontitis microenvironment increased the secretion of inflammatory cytokines of PDLSCs. Under SMS, different inflammatory cytokines were up-regulated by different extents, among which IL-6 and IL-8 were increased considerably, which indicates that IL-6 and IL-8 were involved in the reaction of PDLSCs to SMS in periodontitis microenvironment.

Key words: periodontitis microenvironment, static mechanical strain, periodontal ligament stem cells, inflammatory cytokine 