title: Hypoxic condition promotes differentiation and mineralization of dental pulp cells in vivo.
abstract: OBJECTIVE
  To investigate the behaviour of dental pulp cells under hypoxic conditions in vivo using an experimental animal model.
  
  
  METHODS
  A mini-screw was inserted into the inferior dental nerve canal of rats to arrest the blood supply, which resulted in a reduced oxygen level in the dental pulps of molar teeth used for the experimental group. The decrease in blood supply was evaluated by injected India ink in transparent specimens. The hypoxia marker hypoxyprobe-1 was investigated by immunohistochemical staining. The mRNA expressions of ATP-binding cassette transporter (ABC) G2 (ABCG2) which is a marker for the capacity to excrete metabolites and for stem-like cells as well as dentine sialophosphoprotein (DSPP) and osteocalcin (OCN) which are markers for mineralization were evaluated by RT-PCR. Protein was evaluated by immunohistochemical staining using ABCG2, dentine sialoprotein (DSP) and OCN.
  
  
  RESULTS
  The evaluation of India ink indicated a decreased blood supply in the transparent specimens, and hypoxyprobe-1 immunohistochemical staining showed positive expression. ABCG2, DSPP and OCN mRNA expressions increased at 7 and 14 days. Immunohistochemically, ABCG2, DSP and OCN-positive cells were localized in the odontoblastic layer.
  
  
  CONCLUSIONS
  Hypoxic conditions promoted mineralization and differentiation of dental pulp cells of the odontoblastic layer.
authors.affiliation: Department of Endodontics and Clinical Cariology, Tokyo Dental College, Chiba, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Matsuoka
authors.forename: K
authors.initials: K
authors.lastname: Matsuzaka
authors.forename: K
authors.initials: K
authors.lastname: Morinaga
authors.forename: T
authors.initials: T
authors.lastname: Inoue
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000378:metabolism; D000818:Animals; D002244:Carbon; D002454:Cell Differentiation / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology*; D003782:Dental Pulp / Q000098:blood supply / Q000166:cytology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005347:Fibroblasts / Q000502:physiology; D007150:Immunohistochemistry; D008297:Male; D023421:Models, Animal; D009804:Odontoblasts / Q000502:physiology; D015675:Osteocalcin / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000378:metabolism; D055114:X-Ray Microtomography; D000099311:Dentin Sialophosphoprotein
chemical_list: D018528:ATP-Binding Cassette Transporters; D002244:Carbon; D016326:Extracellular Matrix Proteins; D015675:Osteocalcin; D010750:Phosphoproteins; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein; C028433:chinese ink
keywords: DSPP; dental pulp; differentiation; hypoxia; in vivo; rat