Hypoxia upregulates the expression of the pluripotency markers in the stem cells from human deciduous teeth

Abstract

Objectives: Cultivation under hypoxia promotes different responses in the mesenchymal stem cells and it has been producing promising results for clinical applications. Pulp tissue from deciduous teeth is a source of stem cells which has a high proliferative potential but this is usually discarded. This study has evaluated the effects of hypoxia on proliferation, apoptosis, and the expression of the pluripotency-related genes of the stem cells from human exfoliated deciduous teeth (SHED). Materials and methods: The cells were isolated from dental pulp (n = 5) and characterized as mesenchymal stem cells, in accordance with the International Society for Cell Therapy. The cells were cultivated under hypoxia (3% oxygen) and compared to the normoxia cells (21% oxygen). The proliferation rate was evaluated by the Ki67 antibody for up to 7 days, while the metabolic activity was measured by the wst-8 assay for up to 14 days. The apoptotic cells were analyzed by Annexin V and propidium iodide staining at 24 h and 4 and 7 days. The expression of the pluripotent genes (OCT4, SOX2, and NANOG) was quantified by qPCR after 24 h, or 7 days, when cultivated under hypoxia or normoxia. Results: No differences in the metabolic activity, the proliferation rate, and the apoptosis of SHED when cultivated under hypoxia or normoxia (p > 0.05) were observed. The expression of the pluripotent genes was significantly higher after 24 h and 7 days of the cells that were exposed to hypoxia (p < 0.01). Conclusion: These findings have indicated an increase of the pluripotency-related genes within 7 days as being the main advantage of SHED culture under hypoxia. Clinical relevance: Hypoxia culture may help maintain the quiescent state of the SHED, which could be advantageous for their future clinical applications.