Evaluation of DNA Damage Induced by Therapeutic Low-Level Red Laser

Abstract

Biological effects of monochromatic lights on cells have aroused interest regarding an active and non-innocuous effect on human skin. The aim of this work was to evaluate DNA damage induced by low-level red laser at doses and frequencies used in therapeutic protocols. For this purpose, E. coli cultures and bacterial plasmids were used to assess bacterial survival, filamentation, DNA lesions and in vitro DNA repair induced by low-level red laser exposure at low doses in continuous wave and pulsed emission mode. Data indicate that low-level red laser does not affect the survival of E. coli cultures, topological forms of DNA, and does not induce DNA lesions targeted by endonuclease IV, formamidopyrimidine DNA glycosylase and endonuclease III, but rather that it induces bacterial filamentation in wild type and DNA repair-deficient E. coli cultures and DNA lesions targeted by exonuclease III. Monochromatic red light could activate survival and/or adaptive mechanisms against harmful radiations.