title: In vitro guidance of dental pulp cells by Nd:YAG laser-irradiated endothelial cells.
abstract: OBJECTIVE
  After endothelial cells were ablated by neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation, we investigated the response of pulp cells by examining the expression of transforming growth factor beta-1 (TGF-β1).
  
  
  BACKGROUND
  The reaction of stimulated blood vessels is related to the initiation of dentinogenesis. After artificial injury of endothelial cells, pulp cells migrate to the site of the injured endothelial cells.
  
  
  METHODS
  Rat aortic endothelial cells were cultured in the lower compartment of the experimental assembly, and a pulsed Nd:YAG laser was used to ablate these cells. Pulp cells were fluorescence labeled and cultured in the upper compartment. After 7-14 days of laser irradiation, total RNA was extracted from the cells in the lower chamber, and RT-PCR was performed to examine the expression of TGF-β1 and osteocalcin mRNA. TGF-β1 was also examined with immunohistochemistry.
  
  
  RESULTS
  Seven days after laser irradiation, migrating pulp cells that expressed TGF-β1 were observed in the lower compartment, and the expression of TGF-β1 mRNA and osteocalcin mRNA was altered. Without laser irradiation, few migrating pulp cells were observed, and the expression of TGF-β1 mRNA and osteocalcin mRNA was weak. These results suggested that TGF-β1 mRNA expression is detected earlier in pulp cells rather than in endothelial cells following injury to endothelial cells.
  
  
  CONCLUSIONS
  Using the Nd:YAG laser as an ablative stimulant, this study model was useful for investigating pulp-endothelial cell interactions in reparative dentinogenesis.
authors.affiliation: Department of Endodontology, Showa University School of Dentistry, Kitasenzoku, Ohta-ku, Tokyo, Japan. yoshik@dent.showa-u.ac.jp
authors.forename: Yoshiko Murakami
authors.initials: YM
authors.lastname: Masuda
authors.forename: Yoshishige
authors.initials: Y
authors.lastname: Yamada
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kimura
mesh_terms: D000535:Aluminum / Q000627:therapeutic use*; D000818:Animals; D002465:Cell Movement / Q000502:physiology / Q000528:radiation effects; D002478:Cells, Cultured; D003782:Dental Pulp / Q000378:metabolism / Q000528:radiation effects*; D003810:Dentinogenesis / Q000235:genetics / Q000502:physiology; D042783:Endothelial Cells / Q000378:metabolism / Q000528:radiation effects; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D028022:Low-Level Light Therapy / Q000379:methods*; D008297:Male; D023421:Models, Animal; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*; D015019:Yttrium / Q000627:therapeutic use*
chemical_list: D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; C503779:yttrium-aluminum-garnet; D015675:Osteocalcin; D015019:Yttrium; D000535:Aluminum