Effects of Hypoxia on HIF and VEGF Expression by HPDLC

Objective: When the damage of microcirculation in periodontal tissue caused by periodontitis, the periodontal tissue will in a hypoxia situation obviously.Ischemic situation in dental lateral force has cause periodontal tissue hypoxia at the process of orthodontic treatment.The expression of hypoxia inducible factor-1á can be activated by oxygen deficiency and some inflammatory cytokines. On the other hand, vascular endothelial growth factor(VEGF), the most important target gene of HIF-1á,plays an important role in angiogenesis and bone remodeling. The aim of this study is to investigate the effects of hypoxia on expression of HIF-1á and VEGF proteins in human periodontal ligament cells.Therefore,we exposure human periodontal ligament cells to hypoxia and normal oxygen tension (normoxia) to simulate the local ischemic model in periodontal tissue cause by periodontitis and smoke. Methods: Human periodontal ligament cells (hPDLCs) were cultured under 20% and 1% O2 for 24h and 48h. Immunohistochemistry metheod was used to localize the distribution of HIF-1á and VEGF in hPDLCs. Results: the expression of HIF-1á in hypoxia groups at 24 hours and 48 hours show a positive reaction while negative positive were observed under normoxic condition. The staining of VEGF was enhancing in a time-dependent manner.The expression of VEGF in hypoxia groups were higher than that in control groups.Conclusion: it is disadvantage for osteogenic ability of periodontal ligament cells under hypoxia environment, and hints that lack of oxygen in periodontal tissue could accelerate the development of periodontitis.