Cobalt Chloride Enhances the Stemness of Human Dental Pulp Cells.
BACKGROUND
Hypoxia is a factor in controlling stem cell stemness. We investigated if cobalt chloride (CoCl2), a chemical agent that mimics hypoxia in vitro, affected human dental pulp cell (hDPC) stemness by examining cell proliferation, stem cell marker expression, and osteogenic differentiation.


METHODS
hDPCs were cultured with or without 25 or 50 μmol/L CoCl2. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine cell proliferation. The number of STRO-1+cells was determined by flow cytometry. The messenger RNA expression of the stem cell markers REX1, OCT4, SOX2, and NANOG and the osteogenic-associated genes ALP, COLI, and RUNX2 were evaluated using reverse transcription polymerase chain reaction or real-time polymerase chain reaction. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) activity and mineralization assays.


RESULTS
Although 25 and 50 μmol/L CoCl2suppressed hDPC proliferation, 50 μmol/L CoCl2increased the number of STRO-1+cells. Moreover, CoCl2dose dependently induced stem cell marker expression. Additionally, CoCl2treatment suppressed osteogenic-associated gene expression, ALP activity, and calcium deposition. The addition of apigenin, a hypoxia-inducible factor 1-alpha inhibitor, reversed the inhibitory effect of CoCl2on ALP activity.


CONCLUSIONS
This study indicated that CoCl2may enhance hDPC stemness.
Department of Pediatric Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Kantaporn
K
Laksana
Department of Pharmacology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Sireerat
S
Sooampon
Department of Anatomy, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand.
Prasit
P
Pavasant
Department of Pediatric Dentistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Electronic address: w.sriarj@gmail.com.
Wannakorn
W
Sriarj
D000469:Alkaline Phosphatase / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003035:Cobalt / Q000494:pharmacology*; D003782:Dental Pulp / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D005434:Flow Cytometry; D006801:Humans; D066298:In Vitro Techniques; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D000071317:Nanog Homeobox Protein / Q000378:metabolism; D050814:Octamer Transcription Factor-3 / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects; D060888:Real-Time Polymerase Chain Reaction; D055748:SOXB1 Transcription Factors / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects*
D051741:Kruppel-Like Transcription Factors; C486780:NANOG protein, human; D000071317:Nanog Homeobox Protein; D050814:Octamer Transcription Factor-3; C494173:POU5F1 protein, human; C527782:SOX2 protein, human; D055748:SOXB1 Transcription Factors; C507976:ZFP42 protein, human; D003035:Cobalt; D000469:Alkaline Phosphatase; C018021:cobaltous chloride
Cobalt chloride; human dental pulp cells; osteogenic differentiation; stemness