SCIeNTIFIC REPORTS | (2018) 8:3419 | DOI:10.1038/s41598-018-21183-6
Exogenous nitric oxide stimulates
the odontogenic dierentiation of
rat dental pulp stem cells
, Yu-feng Mei
, Ikiru Atsuta
, Atsushi Danjo
, Haruyoshi Yamaza
, Kento Nishida
, Ronghao Tang
, Yukari Kyumoto-Nakamura
, Toshio Kukita
, Fusanori Nishimura
& Takayoshi Yamaza
Nitric oxide (NO) is thought to play a pivotal regulatory role in dental pulp tissues under both
physiological and pathological conditions. However, little is known about the NO functions in dental
pulp stem cells (DPSCs). We examined the direct actions of a spontaneous NO gas-releasing donor,
NOC-18, on the odontogenic capacity of rat DPSCs (rDPSCs). In the presence of NOC-18, rDPSCs were
transformed into odontoblast-like cells with long cytoplasmic processes and a polarized nucleus. NOC-
18 treatment increased alkaline phosphatase activity and enhanced dentin-like mineralized tissue
formation and the expression levels of several odontoblast-specic genes, such as runt related factor
2, dentin matrix protein 1 and dentin sialophosphoprotein, in rDPSCs. In contrast, carboxy-PTIO, a NO
scavenger, completely suppressed the odontogenic capacity of rDPSCs. This NO-promoted odontogenic
dierentiation was activated by tumor necrosis factor-NF-κB axis in rDPSCs. Further in vivo study
demonstrated that NOC-18-application in a tooth cavity accelerated tertiary dentin formation, which
was associated with early nitrotyrosine expression in the dental pulp tissues beneath the cavity. Taken
together, the present ndings indicate that exogenous NO directly induces the odontogenic capacity of
rDPSCs, suggesting that NO donors might oer a novel host DPSC-targeting alternative to current pulp
capping agents in endodontics.
Primary odontoblasts, which are cranial neural crest cell-derived ectodermal mesenchymal stem cells present in
the dental papilla, form the primary dentin during tooth development and secondary dentin aer tooth erup-
tion. When the dentin detects various noxious stimuli, such as bacterial toxins, mechanical trauma, and/or tooth
preparation, tertiary dentin is formed at the dentin-pulp border beneath the injured dentin as part of the tissue
. Tertiary dentinogenesis is approved for use aer vital pulp therapy. Tertiary dentin is divided into
reactionary and reparative dentin according to the response of the primary odontoblasts. Reactionary dentin
is formed by the post-mitotic primary odontoblasts that survive aer tooth injury, while reparative dentin is
reconstructed by newly dierentiated odontoblasts, which are recruited from odontogenic stem/progenitor cells.
A novel odontogenic mesenchymal stem cell (MSC) population, the dental pulp stem cells (DPSCs), have
been successfully isolated from the dental pulp tissue of permanent teeth
. DPSCs are a clonogenic popula-
tion that exhibits stem cell-like properties, including self-renewal capacity, high cell proliferation ability, and
. DPSCs express runt related factor 2 (RUNX2) and dentin sialophosphoprotein
(DSPP) genes under odontogenic culture conditions, and they exhibit a capacity for forming dentin-pulp complex
Department of Molecular Cell Biology and Oral Anatomy, Division of Oral Sciences, Kyushu University Graduate
School of Dental Science, Fukuoka, Japan.
Section of Periodontology, Division of Oral Rehabilitation, Faculty of
Dental Science, Kyushu University, Fukuoka, Japan.
Research Fellow of Japan Society for the Promotion of Science,
Key Laboratory of Oral Diseases of Jiangsu Province and Stomatological School of Nanjing Medical
University, Nanjing, Jiangsu, China.
Department of Pediatric and Preventive Dentistry, The Aliated Stomatological
Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
Section of Implant and Rehabilitative Dentistry,
Division of Oral Rehabilitation, Faculty of Dental Science, Kyushu University, Fukuoka, Japan.
Department of Oral
and Maxillofacial Surgery, Faculty of Medicine, Saga University, Saga, Japan.
Department of Pediatric Dentistry,
Division of Oral Health, Growth & Development, Kyushu University Graduate School of Dental Science, Fukuoka,
Kyushu University School of Dentistry, Fukuoka, Japan. Soichiro Sonoda and Yu-feng Mei contributed
equally to this work. Correspondence and requests for materials should be addressed to T.Y. (email: yamazata@
Received: 7 December 2017
Accepted: 31 January 2018
Published: xx xx xxxx