Influence of hypoxia on proliferation，migration，and insulin-like growth factor-1 expression of human periodontal ligament cells

Abstract:

Objective：To investigate the influence of hypoxia on the bioactivities of human periodontal ligament fibroblasts（hPDLCs）. Methods：The fifth-generation hPDLCs were selected and cultured under the condition of severe hypoxia（1% O2），mild hypoxia（5% O2），or normoxia（21% O2）. MTT assay was used to measure the proliferation rate of hPDLCs. An inverted microscope was used to ob－serve cell morphological changes. Wound healing assay was used to observe the migration ability of hPDLCs. Immunofluorescence staining was used to measure the expression and distribution of hypoxia inducible factor-1（HIF-1） in hPDLCs，and RT-PCR and Western blot were used to measure the mRNA and protein expression of HIF-1 and insulin-like growth factor-1（IGF-1） under dif－ferent levels of O2. Results：Compared with normal hPDLCs，the hPDLCs cultured in 1% O2 had a significant reduction in cell number in a microscopic field，with sparse arrangement and a change in structure. The growth rate of hPDLCs decreased with the reduction in oxygen concentration；the lower the oxygen concentration，the slower the proliferation rate. At 72 hours after scratch in the wound healing assay，hPDLCs migrated to the scratched area in all three groups，but the severe hypoxia group had a significantly lower mi－gration rate than the mild hypoxia group and the normoxia group（0.917±0.023 vs. 0.742±0.046/0.453±0.039，F=530.237，P=0.002）. HIF/DAPI staining showed that under the condition of normal oxygen，HIF-1 was mainly expressed in the cytoplasm，and with the gradual reduction in oxygen concentration，HIF-1 gradually mi－grated to the nucleus. Conclusion：Hypoxia can inhibit the pro－liferation and migration of hPDLCs and change their morpholo－gy. Under the hypoxic condition，HIF-1 gradually migrates from the cytoplasm to the nucleus，and there are increases in the ex－pression of HIF-1 and IGF-1，suggesting that hypoxia has cer－tain influence on the bioactivity of hPDLCs.