Effect Of Stretch Force On Proliferation And Differentiation Of Osteoblasts Stimulated By Lipopolysaccharide

Purpose : This study aims to research the effects of stretch stress on proliferation and mineralization of mouse osteoblast MC3T3-E1 which stimulated by lipopolysaccharide from Porphyromonas gingivalis(Pg-LPS).Methods:(1)The mouse osteoblast MC3T3-E1 was stimulated with 0?g/ml?0.25?g/ml?0.5?g/ml?1.0?g/ml?5.0?g/ml?10.0?g/ml and 100.0?g/ml concentrations of Pg-LPS,then the cells of proliferation activity was detected by MTT assay after 12h?24h?48h and 72 h.The protein expression of TNF-? and IL-6 in osteoblasts exposed to different concentrations for 24 h was detected by ELISA kit.(2)The effects of stretch stress on the proliferation and differentiation of osteoblast stimulated by lipopolysaccharidewere studied:The osteoblast was stimulatedby screening the optimal concentration of Pg-LPS.Then the osteoblasts were treated with 4%,8% and 16% stretch stress respectively for 8h,and the negative control group and the positive control group were set up.Cell proliferation activity was detected by MTT assay,ALP activity was detected by ALP kit.MC3T3-E1 stimulated by Pg-LPS which was induced by osteogenesis,treated with 8% stretch stress for 8 hours per day,then alizarin red staining at 21 days.Results: Different concentrations of Pg-LPS stimulated osteoblasts for the same time,compared with the control group,Pg-LPS could significantly inhibit the proliferation of osteoblasts.With the increase of Pg-LPS concentration,the cell proliferation rate was lower.From the concentration of 0.5 ?g/ml,the cell proliferation rate was significantly different from the control group(p < 0.001).In view of the fact that the cell activity was too low to be suitable for other testing indexes,the second experiment stimulated osteoblasts with 1.0 ?g/ml Pg-LPS for stress loading.Under the same concentration of Pg-LPS,the cell proliferation rate decreased significantly at 24 h compared with 12 h,and after 24 h,the cell proliferation rate decreased nosignificantly with the prolongation of the time.Therefore,Pg-LPS was used to stimulate 24 h as time node in follow-up experiments.The expression of TNF-? and IL-6 in osteoblasts increased with the increase of Pg-LPS concentration.There was a significant difference between the two groups(P < 0.05).When the stress was applied to the osteoblasts stimulated by for 8 h,the MTT detection values of the osteoblasts in inflammatory environment were all lower than control group,and and at 16% stretch stress,cell proliferation rate is the lowest(P<0.001).The activity of ALP in osteoblasts decreased with the increase of tensile stress,and the difference was significant compared with the control group(P < 0.05).The number of mineralized nodules decreased gradually with the increase of force value.Conclusion: 1.Pg-LPS inhibits the proliferation of MC3T3-E1 in a concentration-dependent manner.The expression of TNF-? and IL-6 protein increased with the increase of Pg-LPS concentration.2.The osteoblasts in stimulated by Pg-LPS inhibited the proliferation of osteoblasts with the increase of stretch stress and the time.Stretch force can inhibit the proliferation and differentiation of osteoblasts stimulated by Pg-LPS.