title: Effects of a polarized light source (400-2000 nm) on Hep.2 and L929 cell lines: a spectroscopic in vitro study.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effects on Hep.2 cells originating from laryngeal carcinomas, and L929 cells originating from a fibroblast line, subjected to polarized light at a wavelength of 400-2000 nm.
  
  
  BACKGROUND
  Recently there has been increased interest in the propagation of polarized light in randomly scattering media such as biological tissues, because of its potential applications in medicine.
  
  
  METHODS
  Irradiation was performed at two time points: T0 (24 h after cell culture) and T48 (48 h after the first irradiation). Cellular viability was assessed using an MTT assay at the following times: T0 (first irradiation), T6 (6 h after the first irradiation), T12 (12 h after the first irradiation), T24 (24 h after the first irradiation), T48 (48 h after the first irradiation), and T72 (72 h after the first irradiation). The results were analyzed using Graphpad Prism software.
  
  
  RESULTS
  The results showed that time influenced the cellular viability of L929 cells of both control (p = 0.0014) and illuminated cultures (p = 0.0035). Significant differences between control cells (p = 0.0001) and illuminated Hep.2 cells (p = 0.0001) were observed. There was a significant difference between the proliferation of the two types of cells illuminated compared to their controls: Hep.2 (p = 0.0001) and L929 (p = 0.0002).
  
  
  CONCLUSIONS
  The use of polarized light on Hep.2 and L929 cells resulted in photobiological effects that need further investigation, as this is the first study using this methodology.
authors: Institute for Research and Development (UNIVAP), São José dos Campos, São Paulo, Brazil.
authors: Kátia Vale Monteiro
authors: KV
authors: De Moura
authors: Cibelle Barbosa
authors: CB
authors: Lopes
authors: Cristina Pacheco
authors: CP
authors: Soares
authors: António Luiz Barbosa
authors: AL
authors: Pinheiro
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000528:radiation effects*; D002470:Cell Survival / Q000528:radiation effects*; D005354:Fibrosarcoma / Q000473:pathology; D005454:Fluorescence Polarization; D006801:Humans; D007822:Laryngeal Neoplasms / Q000473:pathology; D013057:Spectrum Analysis; D014407:Tumor Cells, Cultured