Photobiology of Low-power Laser Effects

Abstract

Quantitative studies have been performed to determine the action of low-intensity visible monochromatic light on various cells (E. coli, yeasts, HeLa, Chinese hamster fibroblasts and human lymphocytes); also irradiation conditions (wavelength, dose and intensity) conducive to vital activity stimulation have been examined. Respiratory chain components are discussed as primary photoacceptors. The possible ways for photosignal transduction and amplification are discussed. It is proposed that enhanced wound healing due to irradiation with low-intensity visible laser light (He-Cd, He-Ne and semiconductor lasers) is due to the increasing proliferation of cells.

Effects of low-level laser therapy on the proliferation and apoptosis of gingival fibroblasts treated with zoledronic acid

“…[13][14][15][16][17][18]25,26 Most of the effects of LLLT have been associated with the activation of mitochondrial cytochrome c oxidase, which leads to increased adenosine triphosphate (ATP) production and the activation of several cell-signalling pathways. 27,28 In the present study, it may be speculated that similar laser biostimulation occurred in those irradiated fibroblasts that presented significantly increased proliferation (Table 3).…”

Stability of dental implants after irradiation with an 830-nm low-level laser: a double-blind randomized clinical study

“…Laser light irradiation has been applied in the medical field and has biostimulatory effects on wound healing, collagen synthesis, and fibroblast proliferation [5][6][7]. In addition, laser light appears to increase mitochondrial respiration and adenosine triphosphate (ATP) synthesis [8,9].…”

Light-emitting diode effects on combined decellularization of tracheae. A novel approach to obtain biological scaffolds

“…Consequently, the ATP synthesis also increases 19 , and so does the variation of the intra and extracellular pH, the metabolism acceleration 29 , and the rate of epithelial cell proliferation 30 , which causes biophysical changes that may lead to an increased rate of exchanges in the cell membrane 31 .…”

“…As well as that, they show that the interactions of the electromagnetic waves with the biological tissue cause the cells to warm up a little, including their mitochondrial membrane, leading to oxidative stress and triggering biochemical reactions that speed up the metabolism by increasing oxygen consumption 32 . A cell is usually able to overcome the effects of stress provided that the disturbances of the redox balance are small, restoring normal intracellular balance with positive stimulatory effects on the cells; largerscale disturbances, however, may be lethal to the cells [17][18][19] . In this sense, we hypothesized that a higher dose, like the dose chosen for this research (15J/cm 2 ), could induce cell death, and consequently to contribute to the decellularization process.…”

“…Even though a cell is usually able to overcome small disturbances of the redox balance, larger-scale disturbances may be lethal to the cells [17][18][19] , such the apoptosis caused by oxidative stress resulting from LED irradiation 17 . Our research group has been interested in suitable scaffolds for tissue engineering for a long time 12,20,21 .…”