title: Effects of Extracellular pH on Dental Pulp Cells In Vitro.
abstract: BACKGROUND
  The proliferation and migration of dental pulp stem cells (DPSCs), a population comprised of dental pulp cells (DPCs), are important processes for pulp tissue repair. Dental pulp is exposed to changes in extracellular pH under various conditions, such as acidosis and exposure to caries-associated bacteria or a pulp capping agent. The objective of this study was to investigate the effects of extracellular pH on DPC proliferation and migration in vitro.
  
  
  METHODS
  To evaluate the proliferation potency of DPCs in various extracellular pH conditions, 2 × 10(4) cells were seeded into 35-mm dishes. The following day, we changed to NaHCO3-free medium, which was adjusted to different extracellular pH levels.
  
  
  RESULTS
  After 120 hours, DPCs cultured in media from a pH of 3.5 to 5.5 showed cell death, those cultured in conditions from a pH of 6.5 to 7.5 showed growth arrest or cell death, and those grown at a pH of 9.5 showed mild proliferation. The migratory activity of living DPCs was not affected by extracellular pH. For histologic analysis, human teeth possessing a small abscess in the coronal pulp chamber were sliced for histologic analysis. Proliferating cell nuclear antigen (PCNA) immunolocalization was used as an index of cell proliferation for the sections and cultured cells. Acidic extracellular pH conditions resulted in reduced numbers of PCNA-positive DPCs in the dishes. As for pulp tissue affected by a small abscess, a PCNA-negative pulp cell layer was observed in close proximity to the infectious lesion.
  
  
  CONCLUSIONS
  Together, these results suggest that an acidic extracellular pH condition is associated with DPC growth arrest or cell death.
authors.affiliation: Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan; Department of Dental Regenerative Medicine, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and Gerontology, Obu, Japan; Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Japan.
authors.forename: Yujiro
authors.initials: Y
authors.lastname: Hirose
authors.affiliation: Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Japan.
authors.forename: Masaya
authors.initials: M
authors.lastname: Yamaguchi
authors.affiliation: Department of Oral and Molecular Microbiology, Osaka University Graduate School of Dentistry, Suita, Japan.
authors.forename: Shigetada
authors.initials: S
authors.lastname: Kawabata
authors.affiliation: Department of Dental Regenerative Medicine, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and Gerontology, Obu, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Murakami
authors.affiliation: Department of Dental Regenerative Medicine, Center of Advanced Medicine for Dental and Oral Diseases, National Center for Geriatrics and Gerontology, Obu, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Nakashima
authors.affiliation: Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Momokazu
authors.initials: M
authors.lastname: Gotoh
authors.affiliation: Department of Urology, Nagoya University Graduate School of Medicine, Nagoya, Japan. Electronic address: toku@med.nagoya-u.ac.jp.
authors.forename: Tokunori
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D000328:Adult; D018929:Cell Culture Techniques; D016923:Cell Death / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects*; D003782:Dental Pulp / Q000166:cytology* / Q000187:drug effects*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008297:Male; D008964:Molar, Third; D057872:Pulp Capping and Pulpectomy Agents / Q000494:pharmacology; D017693:Sodium Bicarbonate / Q000494:pharmacology; D013234:Stem Cells / Q000187:drug effects
chemical_list: D057872:Pulp Capping and Pulpectomy Agents; D017693:Sodium Bicarbonate
keywords: Cell death; dental pulp cells; extracellular pH; growth arrest; migration; proliferation