title: Low-level laser therapy induces differential expression of osteogenic genes during bone repair in rats.
abstract: OBJECTIVE
  The aim of this study was to measure the temporal pattern of the expression of osteogenic genes after low-level laser therapy during the process of bone healing. We used quantitative real-time polymerase chain reaction (qPCR) along with histology to assess gene expression following laser irradiation on created bone defects in tibias of rats.
  
  
  METHODS
  The animals were randomly distributed into two groups: control or laser-irradiated group. Noncritical size bone defects were surgically created at the upper third of the tibia. Laser irradiation started 24 h post-surgery and was performed for 3, 6, and 12 sessions, with an interval of 48 h. A 830 nm laser, 50 J/cm(2), 30 mW, was used. On days 7, 13, and 25 post-injury, rats were sacrificed individually by carbon dioxide asphyxia. The tibias were removed for analysis.
  
  
  RESULTS
  The histological results revealed intense new bone formation surrounded by highly vascularized connective tissue presenting slight osteogenic activity, with primary bone deposition in the group exposed to laser in the intermediary (13 days) and late stages of repair (25 days). The quantitative real-time PCR showed that laser irradiation produced an upregulation of BMP-4 at day 13 post-surgery and an upregulation of BMP4, ALP, and Runx 2 at day 25 after surgery.
  
  
  CONCLUSIONS
  Our results indicate that laser therapy improves bone repair in rats as depicted by differential histopathological and osteogenic genes expression, mainly at the late stages of recovery.
authors.affiliation: Department of Physiotherapy, Federal University of São Carlos, Brazil.
authors.forename: Elaine
authors.initials: E
authors.lastname: Fávaro-Pípi
authors.forename: Daniel Araki
authors.initials: DA
authors.lastname: Ribeiro
authors.forename: Juliana Uema
authors.initials: JU
authors.lastname: Ribeiro
authors.forename: Paulo
authors.initials: P
authors.lastname: Bossini
authors.forename: Poliani
authors.initials: P
authors.lastname: Oliveira
authors.forename: Nivaldo A
authors.initials: NA
authors.lastname: Parizotto
authors.forename: Carla
authors.initials: C
authors.lastname: Tim
authors.forename: Heloísa Sobreiro Selistre
authors.initials: HS
authors.lastname: de Araújo
authors.forename: Ana Claudia Muniz
authors.initials: AC
authors.lastname: Renno
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000528:radiation effects*; D028022:Low-Level Light Therapy; D008297:Male; D010012:Osteogenesis / Q000235:genetics* / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar; D013977:Tibia / Q000473:pathology / Q000528:radiation effects