Regulation of the stromal cell-derived factor-1alpha-CXCR4 axis in human dental pulp cells.
BACKGROUND
Although the presence of the stromal cell-derived factor (SDF)-1alpha-CXCR4 axis has been reported in dental pulp tissue, little has been known about the underlying regulation of this axis in dental pulp stem cells (DPSCs). The purpose of this study was to investigate whether inflammation or hypoxia can regulate this axis in cultured human dental pulp cells (DPCs).


METHODS
Primary cultures of DPCs were stimulated by various concentrations of lipopolysaccharide (LPS) for 48 hours, and the production of SDF-1alpha or CXCR4 was assessed through the enzyme-linked immunosorbent assay and Western blotting, respectively. Additionally, DPCs were incubated in a hypoxic condition (1% O(2)) for 24 hours, and the cell proliferation ability was detected by methylthiazol tetrazolum assay. Quantitative reverse-transcription polymerase chain reaction (RT-PCR) was used to observe messenger RNA level changes of hypoxia inducible factor-1alpha(HIF-alpha), SDF-1alpha, and CXCR4. The effects of hypoxia on cell migration ability were further confirmed by transmigration assay.


RESULTS
All concentrations of LPS inhibited SDF-1alpha production except that 1 microg/mL LPS increased the expression of CXCR4. Hypoxia promoted the proliferation of DPCs in a 24-hour culture period. Quantitative RT-PCR showed that messenger RNA levels of HIF-alpha and CXCR4 increased, whereas SDF-1alpha decreased in hypoxic DPCs. Transmigration assay indicated that hypoxia increased the migration ability of DPCs.


CONCLUSIONS
These results suggested that inflammation and hypoxia might play an important role in regulating the SDF-1alpha-CXCR4 axis, which further recruits DPSCs to participate in reparative dentinogenesis.
Gong
Qi-mei
QM
Department of Operative Dentistry and Endodontics, Guanghua School and Hospital of Stomatology & Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong, China.
Quan
Jing-jing
JJ
Jiang
Hong-wei
HW
Ling
Jun-qi
JQ
D000293:Adolescent; D000328:Adult; D015687:Cell Hypoxia / Q000502:physiology*; D049109:Cell Proliferation; D002478:Cells, Cultured; D054377:Chemokine CXCL12 / Q000187:drug effects / Q000378:metabolism*; D003782:Dental Pulp / Q000166:cytology / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004731:Endotoxins / Q000008:administration & dosage; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D008070:Lipopolysaccharides / Q000008:administration & dosage; D019718:Receptors, CXCR4 / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D018709:Statistics, Nonparametric; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D055815:Young Adult
C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; D004731:Endotoxins; D008070:Lipopolysaccharides; D019718:Receptors, CXCR4