| Objective:The pivotal role of chemokine stromal-cell-derived factor-1(SDF-1) in bone marrow-derived mesenchymal stem cells (MSCs) recruitment and tissue regeneration has already been reported. However, its roles in human periodontal ligament stem cells (PDLSCs) remain unknown. PDLSCs, isolated from human periodontal ligament, are capable of differentiating into cementoblast-like cells, osteoblastic cells, adipocytes, and collagen-forming cells cultured in appropriate medium and generating a cementum/PDL-like structure in animal periodontal defects models in vivo. Thus they were regarded as candidates for periodontal tissue regeneration and were used in stem cells-based periodontal tissue engineering. The expression of chemokine receptor on PDLSCs and the migration of these cells induced by chemokine and their subsequent function of tissue repair may be a crucial procedure for periodontal tissue regeneration. The aim of this study was to investigate the expression of chemokine receptor CXCR4 and the migration, activation, proliferation and differentiation potential of PDLSCs stimulated with SDF-1.Methods:Human PDL cells were obtained from clinically healthy premolars extracted for orthodontic reasons and used to isolate PDLSCs by single cell derived-colony selection. The expression of Vimentin and STRO-1 on PDLSCs was demonstrated with immunohistochemical staining. The expression of chemokine SDF-1 receptor CXCR4 on PDLSCs was detected by real-time PCR and immunocytochemical Staining. MTT assay and BrdU incorporation assay were used to determine the viability, proliferation of PDLSCs stimulated with SDF-1. Type I collagen and alkaline phosphatase were detected by real-time PCR to determine the effects of SDF-1 on PDLSCs differentiation. The chemotactic effect of SDF-1 on PDLSCs was detected using a 24-multiwell chemotaxis assay. Differences among different groups were analyzed by one-way analysis of variance (ANOVA) using SPSS. Values of P<0.05 were considered statistically significant.Results:Human PDLSCs displayed positive staining for Vimentin and expressed mesenchymal stem-cell marker STRO-1. Real-time PCR analysis confirmed the expression of chemokine receptor CXCR4 in each batch of PDLSCs at mRNA level; Qualitative immunocytochemical staining of human PDLSCs demonstrated that these cells expressed chemokine receptor for CXCR4 at protein level. SDF-1 promoted the activation and proliferation of PDLSCs in comparison with DMEM alone (P<0.05). Real-time PCR demonstrated that SDF-1 significantly increased type I collagen level (P<0.01), with little effect on alkaline phosphatase level(P>0.05). SDF-1 significantly stimulated the migration of human PDLSCs at concentrations between 100ng/ml and 400ng/ml compared with negative controls (P<0.05) and the maximum dose-response was at 200ng/ml. Treatment with CXCR4 neutralizing antibody, an antagonist for CXCR4, reduced the migratory effect significantly compared with negative controls (P<0.05).Conclusion:Here we report that human PDLSCs express chemokine CXCR4, and for the first time we demonstrate a dose-dependent migratory effect of chemokine SDF-1 on PDLSCs and the results suggested that the migration induced by SDF-1 was mediated by CXCR4. SDF-1/CXCR4 may have the potential of guiding PDLSCs to destructive periodontal tissue followed by promoting the activation and proliferation and by influencing the differentiation of these stem cells to promote periodontal tissue regeneration in vivo. |
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