Effect of laser therapy on DNA damage

Fonseca, A S; Moreira, Thiago O.; Paixão, Deise L.; Farias, Fernanda M.; Guimarães, Oscar Roberto; Paoli, Severo de; Geller, Mauro; Paoli, Flávia de

doi:10.1002/lsm.20921

Cited by 56 publications

(77 citation statements)

References 46 publications

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“…Laser exposure and zymosan-induced did cause neither DNA fragmentation nor cell death by caspase-6 pathway. Several studies have been reported controversial and possible adverse effects on cells and data about DNA damage after laser exposure in eukaryotic 42,43 and prokaryotic cells 32,[44][45] at different powers, wavelengths and fluences. In addition, as regard to DNA, a variety of studies have suggested that exposure to red and near infrared low-intensity lasers could induce adaptation or DNA damage at a sub-lethal level 32, 45 .…”

Section: Discussionmentioning

confidence: 98%

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Low-intensity infrared laser effects on zymosan-induced articular inflammatory response

et al. 2015

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Low-level therapy laser is a phototherapy treatment that involves the application of low power light in the red or infrared wavelengths in various diseases such as arthritis. In this work, we investigated whether low-intensity infrared laser therapy could cause death by caspase-6 apoptosis or DNA damage pathways in cartilage cells after zymosaninduced articular inflammatory process. Inflammatory process was induced in C57BL/6 mouse by intra-articular injection of zymosan into rear tibio-tarsal joints. Thirty animals were divided in five groups: (I) control, (II) laser, (III) zymosan-induced, (IV) zymosan-induced + laser and (V). Laser exposure was performed after zymosan administration with low-intensity infrared laser (830 nm), power 10 mW, fluence 3.0 J/cm 2 at continuous mode emission, in five doses. Twenty-four hours after last irradiation, the animals were sacrificed and the right joints fixed and demineralized. Morphological analysis was observed by hematoxylin and eosin stain, pro-apoptotic (caspase-6) was analyzed by immunocytochemistry and DNA fragmentation was performed by TUNEL assay in articular cartilage cells. Inflammatory process was observed in connective tissue near to articular cartilage, in IV and V groups, indicating zymosan effect. This process was decreased in both groups after laser treatment and dexamethasone. Although groups III and IV presented higher caspase-6 and DNA fragmentation percentages, statistical differences were not observed when compared to groups I and II. Our results suggest that therapies based on low-intensity infrared lasers could reduce inflammatory process and could not cause death by caspase-6 apoptosis or DNA damage pathways in cartilage cells after zymosan-induced articular inflammatory process.

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Section: Discussionmentioning

confidence: 98%

“…On the other hand, low intensity lasers at therapeutic doses could induce free radicals generation 10 and sublethal DNA lesions 32 . Some studies have been reported the subcellular effects, such as phototherapy-induced apoptosis by mitochondrial pathway [33][34][35] .…”

Section: Discussionmentioning

confidence: 99%

Low-intensity infrared laser effects on zymosan-induced articular inflammatory response

et al. 2015

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“…Biological effects caused by free radicals from laser light are controversial and possible adverse effects on cells and data about DNA damage after laser exposure have been reported in eukaryotic [10][11][12][13][14] and prokaryotic cells [15][16][17][18][19][20][21][22][23] , at different powers, wavelengths and fluences. In addition, as regard to DNA, a variety of studies have suggested that exposure to red and near infrared low-intensity lasers could induce adaptation or DNA damage at a sub-lethal level.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, as regard to DNA, a variety of studies have suggested that exposure to red and near infrared low-intensity lasers could induce adaptation or DNA damage at a sub-lethal level. 16,18,[24][25][26][27] Chromatin organization changes, ploidy degrees and DNA fragmentation may be investigated by image analysis densitometry of Feulgen-stained nuclei, using geometric, densitometric and textural parameters. Feulgen reaction can be considered a sensitive method for the DNA evaluation in different cell types under various physiological and pathological conditions and it allows the reliable and rapid estimation of nuclear DNA contents.…”

Section: Introductionmentioning

confidence: 99%

DNA fragmentation and nuclear phenotype in tendons exposed to low-intensity infrared laser

et al. 2015

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Clinical protocols are recommended in device guidelines outlined for treating many diseases on empirical basis. However, effects of low-intensity infrared lasers at fluences used in clinical protocols on DNA are controversial. Excitation of endogenous chromophores in tissues and free radicals generation could be described as a consequence of laser used. DNA lesions induced by free radicals cause changes in DNA structure, chromatin organization, ploidy degrees and cell death. In this work, we investigated whether low-intensity infrared laser therapy could alter the fibroblasts nuclei characteristics and induce DNA fragmentation. Tendons of Wistar rats were exposed to low-intensity infrared laser (830 nm), at different fluences (1, 5 and 10 J/cm 2 ), in continuous wave (power output of 10mW, power density of 79.6 mW/cm 2 ). Different frequencies were analyzed for the higher fluence (10 J/cm 2 ), at pulsed emission mode (2.5, 250 and 2500 Hz), with the laser source at surface of skin. Geometric, densitometric and textural parameters obtained for Feulgen-stained nuclei by image analysis were used to define nuclear phenotypes. Significant differences were observed on the nuclear phenotype of tendons after exposure to laser, as well as, high cell death percentages was observed for all fluences and frequencies analyzed here, exception 1 J/cm 2 fluence. Our results indicate that low-intensity infrared laser can alter geometric, densitometric and textural parameters in tendon fibroblasts nuclei. Laser can also induce DNA fragmentation, chromatin lost and consequently cell death, using fluences, frequencies and emission modes took out from clinical protocols.

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“…The laser radiation energy is transformed in a primary photosignal and in sequence it is transduced and amplified into cells . It is thought that, in this transduction process, there is production of free radicals , and these reactive species could react with intracellular molecules, including DNA and membrane lipids .…”

Section: Introductionmentioning

confidence: 99%

DNA damage in blood cells exposed to low‐level lasers

et al. 2015

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Effect of laser therapy on DNA damage

Abstract: This study shows a protective effect or DNA repair mechanism induction by pre-exposure to low intensity red laser on the lethal action of oxidant agents and, therefore, laser therapy protocol should consider fluencies, wavelength and tissue conditions before beginning treatment.

Cited by 56 publications

References 46 publications

Low-intensity infrared laser effects on zymosan-induced articular inflammatory response

Low-intensity infrared laser effects on zymosan-induced articular inflammatory response

DNA fragmentation and nuclear phenotype in tendons exposed to low-intensity infrared laser

DNA damage in blood cells exposed to low‐level lasers

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