VEGF-A/VEGFR2 Axis Promotes HDPSCs Migration Via FAK/PI3K/Akt and p38MAPK Pathways

Objectives: To investigate the effects of vascular endothelial growth factor A (VEGF-A) and the underlying molecular mechanisms in the migration of human dental pulp stem cells (hDPSCs).
Methods: The expression of VEGF-A in inflammatory pulp tissue and dental pulp cells was examined by qRT-PCR and immunofluorescence staining. The migration of hDPSCs was detected using transwell migration chambers and wound healing assay. The activation of FAK, PI3K, Akt and p38 signalling was evaluated by Western blot analysis. Silence RNA (siRNA) technology was utilised to knockdown the expression of VEGFR1 (Flt-1) and VEGFR2 (Flk-1/KDR). SU5416 (inhibitor of VEGFR2) was employed to investigate the effect of VEGFR2 on the migratory mechanism of hDPSCs. Data were analysed statistically using Student’s t-test or one-way ANOVA.
Results: The expression levels of VEGF-A in inflammatory pulp tissue in vivo and LPS-stimulated dental pulp cells in vitro were significantly higher than those in control groups (P < 0.05). VEGF-A promoted the migration of hDPSCs in a concentration-dependent manner. Several signalling pathways, FAK, PI3K, Akt and p38, were activated by VEGF-A in a dose- and time-dependent manner in hDPSCs. The VEGF-A-induced migration of hDPSCs was inhibited with drug inhibitors such as PF573228 (inhibitor of FAK), LY294002 (inhibitor of PI3K), SB203580 (inhibitor of p38) and SU5416 (P < 0.05). These signalling pathways activated by VEGF-A stimulation were suppressed by pre-treatment with inhibitor of VEGFR2 (SU5416) or transfection with siRNA of VRGFR2 (P < 0.05) but not VEGFR1 siRNA.
Conclusions: VEGF-A/VEGFR2 axis promoted hDPSCs migration via the FAK/PI3K/Akt and p38 MAPK signalling pathways. These findings reveal a novel molecular mechanism of cell migration of hDPSCs, which may contribute to the remodelling of pulp and dentin.