title: Phenotype characterization of pericytes during tissue repair following low-level laser therapy.
abstract: OBJECTIVE
  The action of low-level laser therapy (LLLT) on pericytes during wound healing is not well established. The objective of this study was to identify the effect of laser treatment on pericytes during tissue repair.
  
  
  METHODS
  Punch biopsies were performed on 40 Wistar rats. Twenty animals had their wounds treated with a dose of 4 J/cm(2) using a 670 nm diode laser (9 mW output, 0.031 W/cm(2)) every other day, while the controls received sham irradiation. Animals were sacrificed 3, 7, 10 and 14 days after punch biopsy. Immunohistochemistry staining with anti-desmin, anti-smooth muscle alpha-actin and anti-NG2 antibodies was used to characterize and count pericytes around blood vessels and myofibroblasts dispersed in the extracellular matrix (ECM). The morphology of pericytes was confirmed by transmission electronic microscopy.
  
  
  RESULTS
  The laser group exhibited significantly more smooth muscle alpha-actin-positive staining cells at day 7 and more desmin-positive staining cells at day 10 around blood vessels. Laser treatment was also associated with higher numbers of NG2-positive staining cells, especially on days 3 and 7 post-biopsy (P<0.05). Ultrastructural findings confirmed the presence of pericytes sharing the basal membrane with endothelial cells.
  
  
  CONCLUSIONS
  LLLT stimulated the proliferation and migration of pericytes to the ECM and their phenotypic modulation to myofibroblasts.
authors.affiliation: Laboratory of Experimental Pathology, Oswaldo Cruz Foundation, Salvador, Brazil. alenamedrado@hotmail.com
authors.forename: Alena
authors.initials: A
authors.lastname: Medrado
authors.forename: Tila
authors.initials: T
authors.lastname: Costa
authors.forename: Thiago
authors.initials: T
authors.lastname: Prado
authors.forename: Sílvia
authors.initials: S
authors.lastname: Reis
authors.forename: Zilton
authors.initials: Z
authors.lastname: Andrade
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D053685:Laser Therapy; D046529:Microscopy, Electron, Transmission; D020286:Pericytes / Q000473:pathology* / Q000648:ultrastructure; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D014945:Wound Healing