Objective The study was aimed to provide insights into cell proliferation ability alteration of human
periodontal ligament fibroblasts（HPDLF） under two different types of stimulation, cyclic tensile and compressive stress, and screen the differentially expressed genes to have a comprehensive understanding of the molecular mechanism of changes in proliferation. Methods Primary HPDLF were subjected to cyclic tensile and compressive stress（0.5 Hz, 4 000 μstrain） for 2 h through a four-point bending strain system. After that, cell proliferation ability was examined by flow cytometry. Then the gene expression profile was investigated by microarray analysis. Results Mechanical stress slowed a down proliferation of cells. S phase cells and proliferation index（PI） decreased. Differentially expressed genes were mainly located at nucleus and focus in transcription factor activity related genes, and most of them were involved in the regulation of transcription factors. Among them, more were in group of compressive stress. Conclusion 1）Under mechanical loading, HPDLF proliferation were slowed and cell cycles were arrested. 2）Cell cycle arrest and the slowdown proliferation, which can be viewed as an adaptation and protection mechanism of cells to have more time to decide how to respond to mechanical stimuli, and the differential gene expression reflect the behavior of cells. The result of the response is gene transcription changes at first, and the most important biological response is the nuclear transcription. 3）HPDLF are more sensitive to cyclic compressive stress.
