In Vivo Analysis of Photobiomodulation Genotoxicity Using the Somatic Mutation and Recombination Test.

Background: Photobiomodulation (PBM) has been studied mainly for its effects on the repair, regeneration, and healing of tissue due to its direct and indirect actions on cell proliferation. However, it is necessary to consider the way in which laser acts, that is, whether it affects the rates of spontaneous mutation and mitotic recombination of cells.

Objective: This study investigated the genotoxic potential of PBM (904 nm) based on an in vivo bioassay that concomitantly evaluates mitotic recombination and point and chromosomal mutations.

Methods: Strains of Drosophila melanogaster that carry specific marker genes were used to detect the induction of mutation and somatic recombination when exposed to different fluences (3, 5, 10, and 20 J/cm²). DNA damage was measured using the somatic mutation and recombination test (SMART), which is based on the identification of wing hair with mutant phenotypes that express lesions at DNA level.

Results: The doses 5, 10, and 20 J/cm² induced significant increase in the total number of spots compared with the negative control. The highest frequency of spots was caused by the 10 J/cm².

Conclusions: Besides recombination events, the quantitative and qualitative analysis of mutant hairs revealed the occurrence of mutagenic events, both punctual and chromosomal. In addition, the results point to a dose-dependent response.