Abstract: BACKGROUND: A large number of studies focus on the effect of inflammatory factors on human periodontal ligament stem cells; however, there are few reports on the expression of chemokine macrophage inflammatory protein-1α in human periodontal ligament stem cells at home and abroad.  
OBJECTIVE: To investigate the effects of different mass concentrations of macrophage inflammatory protein 1α on the proliferation, apoptosis, and migration of human periodontal ligament stem cells and the correlation of Notch signaling pathway.
METHODS:  Healthy orthodontic reduced premolars were extracted from patients aged 12-25 years (all signed informed consent), and human periodontal ligament stem cells were isolated and cultured by tissue block method combined with enzymatic digestion. Passage 3 human periodontal ligament stem cells at logarithmic growth stage were divided into control group, 1, 10, 100 mg/L macrophage inflammatory protein-1α groups. Cell proliferation was detected by CCK-8 assay at 1, 3, 5, and 7 days. At 48 hours, the apoptotic ability of each group was detected by flow cytometry. Cell migration ability of each group was detected by Transwell chamber test. ELISA was used to detect the level of secreted tumor necrosis factor α. qRT-PCR and western blot assay were used to detect the mRNA and protein expression levels of Notch1 and Hes1.  
RESULTS AND CONCLUSION: (1) 1 mg/L macrophage inflammatory protein-1α had no significant effect on the biological behavior of human periodontal ligament stem cells. 10 mg/L macrophage inflammatory protein-1α significantly promoted the proliferation and migration of human periodontal ligament stem cells, and 100 mg/L macrophage inflammatory protein-1α significantly promoted the apoptosis of human periodontal ligament stem cells, inhibited the proliferation and migration of human periodontal ligament stem cells. (2) 1 mg/L macrophage inflammatory protein-1α had no significant effect on the expression of Notch1 and Hes1 proteins in human periodontal ligament stem cells. 10 mg/L macrophage inflammatory protein-1α had no significant effect on the expression of Notch1 protein in human periodontal ligament stem cells, but could down-regulate the expression level of Hes1 protein in the cells. 100 mg/L macrophage inflammatory protein-1α could up-regulate the expression of Notch1 and Hes1 protein in cells. (3) The level of tumor necrosis factor α secreted by  human periodontal ligament stem cells of the 1 mg/L macrophage inflammatory protein-1α group was not significantly different from that of the control group. 10 mg/L macrophage inflammatory protein-1α promoted the secretion of tumor necrosis factor α; 100 mg/L macrophage inflammatory protein-1α inhibited the secretion of tumor necrosis factor α. (4) These results exhibited that 10 mg/L macrophage inflammatory protein-1α promoted the proliferation, migration and tumor necrosis factor α secretion of human periodontal ligament stem cells, and the mechanism might be related to the down-regulation of Notch signaling pathway. 100 mg/L macrophage inflammatory protein-1α inhibited the proliferation and migration of human periodontal ligament stem cells and the secretion of tumor necrosis factor α, and promoted the apoptosis of human periodontal ligament stem cells. The mechanism may be related to the up-regulation of Notch signaling pathway.

Key words: human periodontal ligament stem cell, macrophage inflammatory protein-1α, Notch signaling pathway, proliferation, migration, apoptosis