Effects of cobalt chloride on the stem cell marker expression and osteogenic differentiation of stem cells from human exfoliated deciduous teeth.

Stem cells from human exfoliated deciduous teeth (SHEDs) are a promising source for tissue engineering and stem cell transplantation. However, long-term in vitro culture and expansion lead to the loss of stemness of SHEDs, compromising their therapeutic benefits. Hypoxia plays an essential role in controlling the stem cell behavior of mesenchymal stem cells (MSCs). Thus, this study aimed to investigate the effects of cobalt chloride (CoCl), a hypoxia-mimetic agent, on the stem cell marker expression and osteogenic differentiation of SHEDs. SHEDs were cultured with or without 50 or 100 μM CoCl. Their proliferation, apoptosis, stem cell marker expression, migration ability, and osteogenic differentiation were examined. Culture with 50 and 100 μM CoCl increased the hypoxia-inducible factor-1 alpha (HIF-1α) protein levels in a dose-dependent manner in SHEDs without inducing significant cytotoxicity. This effect was accompanied by an increase in the proportion of STRO-1 cells. CoCl significantly increased the expression of stem cell markers (OCT4, NANOG, SOX2, and c-Myc) in a dose-dependent manner. The migration ability was also promoted by CoCl treatment. Furthermore, SHEDs cultured in osteogenic medium with CoCl showed a dose-dependent reduction in alkaline phosphatase (ALP) activity and calcium deposition. The expression of osteogenic-related genes was also suppressed by CoCl, especially in the 100-μM CoCl group. In conclusion, CoCl increased the expression of stem cell markers and inhibited the osteogenic differentiation of SHEDs. These findings may provide evidence supporting the use of in vitro hypoxic environments mimicked by CoCl in assisting the clinical application of SHEDs.