Secretion of VEGF, TGF-B1 and IGF-1 by Dental- Derived Stem Cells under Hypoxic Conditions

Dental-derived stem cells (DSC) are important cells in tissue regeneration following tissue destruction. One of the environmental conditions in the injured tissue is reduce in oxygen level (hypoxia) but the effect of hypoxia on the DSC is not fully elucidated. Objectives: This study aims to evaluate the effect of hypoxia on growth factor production and expression of dental-derived stem cells. Methods : Rat periodontal ligament stem cells (PDLSCs) and dental pulp stem cells (DPSCs) were cultured in serum-free media for two or three days. When the cells achieved 70% confluence, they were incubated under normoxia (21%) or hypoxia (2%) conditions, before the conditioned media (CM) that contained the cells’ secretomes were collected and compared with bone marrow stem cells (BMSCs).ELISA kits were used to analyze VEGF, TGF-β 1 and IGF-1 levels in the collected CM. The reverse transcriptase-polymerase chain reaction (RT-PCR) was then used to determine the gene expression of the growth factors. Results : Hypoxia incubation increased growth factor secretion by the dental-derived stem cells, and these findings were also supported by the gene expression analysis of VEGF and TGF-β1 . Interestingly, IGF-1 was only detected in PDLSC CM, and these data were supported by prominent IGF-I gene expression and an inverse relationship with IGF-BP1 expression by PDLSC, compared with DPSCs and BMSCs. TGF-β 1 secretion by BMSCs was not influenced by hypoxic incubation. Conclusion : Hypoxic incubation of the dental-derived stem cells alters growth factor content in the secretomes, and IGF-1 was only detected in the PDLSC secretome