title: Expression of angiogenic factors in rat periapical lesions.
abstract: BACKGROUND
  Angiogenic factors such as VEGFR2 (vascular endothelial cell growth factor receptor 2), Bcl-2 (a prosurvival and proangiogenic signaling molecule), and chemokine (C-X-C motif) ligand 1 (CXCL1) (a proangiogenic chemokine) may have critical roles in enhancing the establishment of apical periodontitis. To understand the role of these factors in the pathogenesis of apical periodontitis, we conducted immunohistochemical and molecular biological analysis.
  
  
  METHODS
  Apical periodontitis was induced in the lower first molars of Wistar rats by making unsealed pulp exposures. After, 14, 21, and 28 days, the molars were retrieved, embedded as frozen sample blocks, and cut in a cryostat. Normal lower first molars served as controls. Immunostaining for CD31 (a marker for endothelial cells), Bcl-2, and real-time polymerase chain reaction analysis of VEGFR2, Bcl-2, CXCL1, and CXCR2 messenger RNA were performed. In the real-time polymerase chain reaction analysis, messenger RNA was extracted from CD31-stained endothelial cells that were retrieved with laser capture microdissection. For statistical analysis of immunohistochemistry, the immunostained area was plotted, and pixel counts were determined. Then, the percentage of the immunostained area in the total area was calculated.
  
  
  RESULTS
  The density of the CD31-stained area increased until 21 days after pulp exposure. On the other hand, Bcl-2-stained area showed the highest density at 14 days (active lesion expanding phase) and then decreased until 28 days (lesion stability phase). VEGFR2, Bcl-2, CXCL1, and CXCR2 messenger RNA expression in endothelial cells showed the highest levels at 14 days and then decreased until 28 days.
  
  
  CONCLUSIONS
  The increase in microvascular density and the up-regulation of VEGFR2, Bcl-2, CXCL1, and CXCR2 messenger RNA expression in endothelial cells took place coincidently with the expanding phase of experimentally induced periapical lesions. These data suggest that these angiogenic factors play a role in the lesion development.
authors.affiliation: Division of Cariology, Operative Dentistry and Endodontics, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Yamanaka
authors.forename: Tomoatsu
authors.initials: T
authors.lastname: Kaneko
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Yoshiba
authors.forename: Reika
authors.initials: R
authors.lastname: Kaneko
authors.forename: Nagako
authors.initials: N
authors.lastname: Yoshiba
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Shigetani
authors.forename: Jacques E
authors.initials: JE
authors.lastname: Nör
authors.forename: Takashi
authors.initials: T
authors.lastname: Okiji
mesh_terms: D043925:Angiogenesis Inducing Agents / Q000032:analysis*; D000818:Animals; D054360:Chemokine CXCL1 / Q000032:analysis; D004396:Coloring Agents; D003789:Dental Pulp Exposure / Q000150:complications; D042783:Endothelial Cells / Q000473:pathology; D004730:Endothelium, Vascular / Q000473:pathology; D006097:Granulation Tissue / Q000473:pathology; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007150:Immunohistochemistry; D061346:Laser Capture Microdissection / Q000379:methods; D008297:Male; D055806:Microvessels / Q000473:pathology; D008967:Molecular Biology; D010010:Osteoclasts / Q000473:pathology; D010482:Periapical Abscess / Q000473:pathology; D010485:Periapical Periodontitis / Q000209:etiology / Q000473:pathology*; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000032:analysis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D060888:Real-Time Polymerase Chain Reaction; D013997:Time Factors; D015854:Up-Regulation; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000032:analysis
chemical_list: D043925:Angiogenesis Inducing Agents; D054360:Chemokine CXCL1; D004396:Coloring Agents; C513297:Cxcl1 protein, rat; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D040301:Vascular Endothelial Growth Factor Receptor-2