Pulp cell responses during hypoxia and reoxygenation in vitro.
The purpose of this study was to investigate pulp cell responses during hypoxia and reoxygenation. Pulp tissues obtained from beagle dogs were cultured. In the control group, pulp cells were incubated in normoxic conditions (20% O2) for 1-4 d. In the hypoxia group, pulp cells were incubated under hypoxic conditions (2% O2) for 1-4 d. In the reoxygenation group, pulp cells were first incubated under hypoxic conditions for 24 h, and were then incubated in normoxic conditions (20% O2) for one to three additional days. Cell viability, MTT (3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction assay, cellular proliferation, and alkaline phosphatase (ALPase) activity were determined. Expression of heat shock protein 70 (HSP70) and vascular endothelial growth factor (VEGF) was analysed by Western blotting. Hypoxia inducible factor-1alpha (HIF-1alpha) in pulp cells was analysed by reverse transcriptase polymerase chain reaction (RT-PCR). The cell growth rate and ALPase activity were significantly higher in the hypoxia group than in the control group. After reoxygenation, cellular proliferation and ALPase activity decreased to the level of the control group while HSP70 expression increased. Hypoxia inducible factor-1alpha expression was detected in pulp cells, and VEGF expression (which is regulated by HIF-1alpha) increased under hypoxic conditions. These results suggest that dynamic responses to hypoxia and reoxygenation occur in pulp cells.
Amemiya
Kei
K
Department of Dental Anesthesiology, Tokyo Dental College, Chiba-city, Japan. kamemiya@tdc.ac.jp
Kaneko
Yuzuru
Y
Muramatsu
Takashi
T
Shimono
Masaki
M
Inoue
Takashi
T
D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D002455:Cell Division / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology*; D002470:Cell Survival / Q000502:physiology; D004396:Coloring Agents; D046508:Culture Techniques; D003782:Dental Pulp / Q000473:pathology / Q000503:physiopathology*; D004285:Dogs; D016228:Endothelial Growth Factors / Q000032:analysis; D018840:HSP70 Heat-Shock Proteins / Q000032:analysis; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins / Q000032:analysis; D008222:Lymphokines / Q000032:analysis; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D020033:Protein Isoforms / Q000032:analysis; D018709:Statistics, Nonparametric; D013778:Tetrazolium Salts; D013844:Thiazoles; D014157:Transcription Factors / Q000032:analysis; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D004396:Coloring Agents; D016228:Endothelial Growth Factors; D018840:HSP70 Heat-Shock Proteins; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D020033:Protein Isoforms; D013778:Tetrazolium Salts; D013844:Thiazoles; D014157:Transcription Factors; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D000469:Alkaline Phosphatase; C022616:thiazolyl blue