Modulation of the Dental Pulp Stem Cell Secretory Profile by Hypoxia Induction Using Cobalt Chloride

The action of stem cells is mediated by their paracrine secretions which comprise the secretory profile. Various approaches can be used to modify the secretory profile of stem cells. Creating a hypoxic environment is one method. The present study aims to demonstrate the influence of CoCl(2) in generating hypoxic conditions in a dental pulp stem cell (DPSCs) culture, and the effect of this environment on their secretory profile. DPSCs that were isolated from human permanent teeth were characterized and treated with different concentrations of CoCl(2) to assess their viability by an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and proliferation by a cell counting kit (CCK)-8 assay. The gene expression level of hypoxia-inducible factor 1-alpha (HIF-1α) was analyzed by quantitative real time polymerase chain reaction (qRT-PCR) to demonstrate a hypoxic environment. Comparative evaluation of the growth factors and cytokines were done by cytometric bead array. Gene expression levels of transcription factors OCT4 and SOX2 were analyzed by qRT-PCR to understand the effect of CoCl(2) on stemness in DPSCs. DPSCs were positive for MSC-specific markers. Doses of CoCl(2,) up to 20 µM, did not negatively affect cell viability; in low doses (5 µM), it promoted cell survival. Treatment with 10 µM of CoCl(2) significantly augmented the genetic expression of HIF-1α. Cells treated with 10 µM of CoCl(2) showed changes in the levels of growth factors and cytokines produced. It was very evident that CoCl(2) also increased the expression of OCT4 and SOX2, which is the modulation of stemness of DPSCs. A CoCl(2) treatment-induced hypoxic environment modulates the secretory profile of DPSCs.