The Preliminary Study About The Mechanical Properties Of HPDLC Effected By Endotoxin

Background and Objectives: Periodontitis is a chronic, non-specific, infectiousdisease which affects periodontal support structures including the gingiva, periodontalmembrane, alveolar bone and cementum. It remains the leading cause of tooth loss andfacilitates changes in vocal pronunciation, as well the function and morphology of themouth cavity.Theperiodontal ligament cells is the primary cells of the periodontaltissue.As mechanics sensitive cell, it plays an important role in the reconstruction andrestoration of periodontal tissue. Living cells possess intrinsic mechanical properties,which in responding to environmental changes adjust corresponding biologicalprocesses through mechanical means.. Cell elastic modulus represents an importantparameter in the study of a cell’s biomechanical properties. It plays a role in cellmotility, cell differentiation and even apoptosis (programmed cell death). Endotoxins,such as the lipopolysaccharides in the outer membrane of gram-negative bacteria cellwalls, are one of the primary causes of periodontal disease. Prior research focused onthe influence endotoxins exert on the HPDLC’s cellular factors and rarely analyzed themechanical properties of the cells. This survey seeks to study the change of elasticmodulus in HPDLC affected by endotoxins using atomic force microscopy, in order tofurther understand the pathogenic mechanisms used by endotoxins in periodontitis.Methods: The primary HPDLC are isolated by means of enzyme digesting tissue blocks,and the experiments use5generations of HPDLC. The HPDLC ultra-structure imagesare obtained by scanning cell under AFM contact mode. The experiment includes onecontrol group, as well as0.1ug/ml LPS stimulation group,1ug/ml LPS stimulation group,10ug/ml LPS stimulation group. Each experimental group was stimulated by acorresponding concentration of LPS for24hours after normal cell culture. AFM with aprobe modified by10mm microspheres was used to display the nucleus area of HPDLCin each group. The cells’ elastic moduli were calculated by means of the Hertz modelthen t-tests were utilized to compare the differences among each experimental group.Results: The elastic moduli of HPDLC in the control group,0.1μg/ml LPSstimulation group,1μg/ml LPS stimulation group,10μg/ml LPS stimulation was1.958±0.922KPa,1.448±0.999,2.477±1.656KPa,3.654±1.926KPa in turn. Statisticalanalysis showed that, the cells in the0.1μg/ml LPS stimulation group had lowerelastic moduli compared with the control group. There were no difference between thecell elasticity modulus in the1μg/ml LPS stimulation group and the control group.The cells in the10μg/ml LPS stimulation group had higher elastic modulus whencompared with the control group. The results show that cell elastic modulus increased asthe endotoxin concentration of each experimental group increased.Conclusion: The mechanical properties HPDLC vary in response to LPS stimulation，this indicates that there may be a new mechanism in LPS which leads to periodontaldisease.