Abstract
Introduction
Human dental apical papilla cells (APCs) have mineralization potential, which plays
a key role in the root development of young permanent teeth. Limited literature is
available about APC mineralization in the presence of inflammatory cytokines. The
purpose of this study was to investigate the effects of tumor necrosis factor-α (TNF-α)
on APC mineralization.
Methods
APC cultures were established with the enzymatic dissociation method in vitro. The viability of APCs treated with TNF-α was investigated using methyl-thiazol-tetrazolium
assays. Cells were then cultured in osteo-/dentinogenic medium with TNF-α, and mineralization
was assessed by alizarin red S staining. Bone sialoprotein (BSP) and dentin sialoprotein
(DSP) were analyzed using immunocytochemistry. Mineralization genes such as BSP, dentin
sialophosphoprotein (DSPP), osteocalcin (OCN), and dentin matrix acidicphosphoprotein-1
(DMP1) were determined with real-time polymerase chain reaction analyses.
Results
The viability of cultured cells was higher with TNF-α concentrations of 10 ng/mL and
50 ng/mL than with 5 ng/mL or in the control group. Alizarin red S staining showed
that APCs had a higher mineralization activity when the osteo-/dentinogenic culture
medium contained 10 ng/mL TNF-α. Immunocytochemical detection showed that the expression
of BSP and DSP was positive in APCs after they were induced in osteo-/dentinogenic
medium. The expression of mineralization genes differed when treated with 10 ng/mL
TNF-α (ie, the expression of DSPP mRNA increased on days 7 and 14, whereas the expression
of DSPP mRNA decreased on day 21).
Conclusions
TNF-α may promote APC mineralization in short-term cultures and inhibit the mineralization
in long-term cultures.
Key Words
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Article info
Footnotes
Supported by a grant from the Independent Innovation Foundation of Shandong University of China (no. 2011JC019) and a grant of the Science and Technique Development Foundation of Shandong province (2010G0020230).
Identification
Copyright
© 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
