title: Stem cell proliferation under low intensity laser irradiation: a preliminary study.
abstract: OBJECTIVE
  Phototherapy with low intensity laser irradiation has shown to be effective in promoting the proliferation of different cells. The aim of this in vitro study was to evaluate the potential effect of laser phototherapy (660 nm) on human dental pulp stem cell (hDPSC) proliferation.
  
  
  METHODS
  The hDPSC cell strain was used. Cells cultured under nutritional deficit (10% FBS) were either irradiated or not (control) using two different power settings (20 mW/6 seconds to 40 mW/3 seconds), with an InGaAIP diode laser. The cell growth was indirectly assessed by measuring the cell mitochondrial activity through the MTT reduction-based cytotoxicity assay.
  
  
  RESULTS
  The group irradiated with the 20 mW setting presented significantly higher MTT activity at 72 hours than the other two groups (negative control--10% FBS--and lased 40 mW with 3 seconds exposure time). After 24 hours of the first irradiation, cultures grown under nutritional deficit (10% FBS) and irradiated presented significantly higher viable cells than the non-irradiated cultures grown under the same nutritional conditions.
  
  
  CONCLUSIONS
  Under the conditions of this study it was possible to conclude that the cell strain hDPSC responds positively to laser phototherapy by improving the cell growth when cultured under nutritional deficit conditions. Thus, the association of laser phototherapy and hDPSC cells could be of importance for future tissue engineering and regenerative medicine. Moreover, it opens the possibility of using laser phototherapy for improving the cell growth of other types of stem cells.
authors.affiliation: Hospital Israelita Albert Einstein, Unit of Bone Marrow Transplantation, São Paulo 05651-901, SP, Brazil.
authors.forename: Fernanda de P
authors.initials: Fde P
authors.lastname: Eduardo
authors.forename: Daniela F
authors.initials: DF
authors.lastname: Bueno
authors.forename: Patricia M
authors.initials: PM
authors.lastname: de Freitas
authors.forename: Márcia Martins
authors.initials: MM
authors.lastname: Marques
authors.forename: Maria Rita
authors.initials: MR
authors.lastname: Passos-Bueno
authors.forename: Carlos de P
authors.initials: Cde P
authors.lastname: Eduardo
authors.forename: Mayana
authors.initials: M
authors.lastname: Zatz
mesh_terms: D000704:Analysis of Variance; D049109:Cell Proliferation / Q000528:radiation effects*; D002478:Cells, Cultured / Q000166:cytology / Q000528:radiation effects; D003782:Dental Pulp / Q000166:cytology; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D066298:In Vitro Techniques; D028022:Low-Level Light Therapy; D011336:Probability; D011829:Radiation Dosage; D012016:Reference Values; D012680:Sensitivity and Specificity; D013234:Stem Cells / Q000166:cytology / Q000528:radiation effects*