Photobiological Basis and Clinical Role of Low-Intensity Lasers in Biology and Medicine

Abstract

The purpose of this article is to provide a comprehensive review on the clinical role of low intensity laser therapy (laser photostimulation) in biology and medicine. Studies on wound healing and pain relief are highlighted to show the clinical efficacy of laser therapy. Controversies about the use of low intensity laser as a therapeutic modality for wound healing and pain relief are presented and a brief explanation is provided to overcome these controversies. The importance of standard parameters is emphasized for the applications of low intensity lasers in biology and medicine. A justification has been made to warrant further research on the use of low intensity laser as a therapeutic modality. Although the therapeutic applications of low intensity laser are imminent, the heterogeneity in treatment protocols and study design calls for a vigilant interpretation of the findings.

Uso combinado da laserterapia de baixa potência e da inibição da ciclooxigenase-2 na reepitelização de ferida incisional em pele de camundongos: um estudo pré-clínico

“…21 -23 According to Karu et al 17.24 and other authors [20][21][22][23] , exposure to LLLT stimulates an extra mitochondrial electrochemical activity and a simultaneous increase in the synthesis of adenosine triphosphate (ATP), in addition to an increase in the intracellular concentration of calcium (Ca +2 ), exerting effects on cellular signaling and increasing the activity of NOS in endothelial cells, which would offer cytoprotection to damage caused by lipid peroxidation induced by LLLT. [14][15][16] A B C D …”

“…[14][15][16] Previous studies in our laboratory as well as others have suggested that photo-stimulation by laser seems to occur during the inflammatory and proliferative phases of wound healing, exactly because of their influence on biomodulation of eicosanoids, especially PGs, and on the oxidative enzyme system of the skin. 1,2,5,[11][12][13][14][15][16][17][18][19] Consequently, studies that show the effects of combined treatments in wound healing are opportune, since both laser therapy and the use of COX inhibitors act during the same time period in the repair process, that is, both separate treatments affect the inflammatory and proliferative phases of skin healing in animals and humans. Considering this scenario, the purpose of this pre-clinical study was to evaluate the isolated and combined effects of low level laser therapy (LLLT) with helium-neon (He-Ne, 632nm) and selective inhibition of cyclooxygenase-2 (COX-2) in the reepithelialization of skin-incisional wounds in mice.…”

“…[3][4][5]17,[20][21][22][23][24] It has also been reported that nitric oxide (NO) produced by activation of the iNOS enzyme in monocytes participates in signaling for deposition of granulation tissue and collagen and for wound contraction (scar formation) via distinct pathways in animal models of wound healing. 3,14,15,17,21,24 Some authors also show biostimulation effects of LLLT on inflammatory cytokines through gene expression modulation of various growth factors such as platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-β), tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ), which are also potentially involved in the healing of skin wounds. 24.25 These regulatory effects of oxidative stress in skin, biomodulation of inflammatory cytokines and growth factors could be related to the histological findings observed in this study, in relation to the isolated treatment with LLLT (He -Ne).…”

“…Low level laser therapy (LLLT) has been mainly and widely used in many biomedical areas in order to modulate inflammatory response and accelerate the tissue repair process. 1,2,[11][12][13][14] Recent investigations show the influence of LLLT in the dynamics of healing of the skin and other tissues; however, there are still some controversies about it because of the wide variability and divergence in irradiation parameters, in addition to discrepancies in the biological findings. [14][15][16] Previous studies in our laboratory as well as others have suggested that photo-stimulation by laser seems to occur during the inflammatory and proliferative phases of wound healing, exactly because of their influence on biomodulation of eicosanoids, especially PGs, and on the oxidative enzyme system of the skin.…”

“…1,2,[11][12][13][14] Recent investigations show the influence of LLLT in the dynamics of healing of the skin and other tissues; however, there are still some controversies about it because of the wide variability and divergence in irradiation parameters, in addition to discrepancies in the biological findings. [14][15][16] Previous studies in our laboratory as well as others have suggested that photo-stimulation by laser seems to occur during the inflammatory and proliferative phases of wound healing, exactly because of their influence on biomodulation of eicosanoids, especially PGs, and on the oxidative enzyme system of the skin. 1,2,5,[11][12][13][14][15][16][17][18][19] Consequently, studies that show the effects of combined treatments in wound healing are opportune, since both laser therapy and the use of COX inhibitors act during the same time period in the repair process, that is, both separate treatments affect the inflammatory and proliferative phases of skin healing in animals and humans.…”