Near infrared low‐level laser therapy and cell proliferation: The emerging role of redox sensitive signal transduction pathways

Abstract

Lasers devices are widely used in various medical fields (eg, surgery, dermatology, dentistry, rehabilitative medicine, etc.) for different applications, ranging from surgical ablation of tissues to biostimulation and pain relief. Laser is an electromagnetic radiation, which effects on biological tissues strongly depends on a number of physical parameters. Laser wavelength, energy output, irradiation time and modality, temperature and tissue penetration properties have to be set up according to the clinical target tissue and the desired effect. A less than optimal operational settings, in fact, could result in a null or even lethal effect. According to the first law of photobiology, light absorption requires the presence of a specific photoacceptor that after excitation could induce the activation of downstream signaling pathways. Low-level lasers operating in the red/near infrared portion of the light spectra are generally used for biostimulation purposes, a particular therapeutic application based on the radiant energy ability to induce nonthermal responses in living cells. Biostimulation process generally promotes cell survival and proliferation. Emerging evidences support a low-level laser stimulation mediated increase in "good" reactive oxygen species, able to activate redox sensitive signal transduction pathways such as Nrf-2, NF-kB, ERK which act as key redox checkpoints.

Low-level laser therapy for the treatment of androgenetic alopecia in Thai men and women: a 24-week, randomized, double-blind, sham device-controlled trial

“…However, CCO has a weak absorption at wavelengths longer than 900 nm, which suggests the existence of other chromophores. Intracellular water in light-sensitive ion channels, such as the transient receptor potential vanilloid, has been proposed as another candidate chromophore, especially at mid-and far-infrared wavelengths, based on its high absorption capacity in the infrared spectrum [20][21][22]. The most widely accepted mechanism of LLLT is that nitric oxide, a competitive inhibitor of oxygen binding, is photodissociated from its binding sites in CCO, allowing an immediate influx of oxygen, which drives the electron transport chain to generate ATP and ROS.…”

Balance between Health Risks and Benefits for Outdoor Workers Exposed to Solar Radiation: An Overview on the Role of Near Infrared Radiation Alone and in Combination with Other Solar Spectral Bands

“…Photobiostimulation, in this context regarded as a beneficial effect, is not related or is not just related to tissue heating, which may be irrelevant or absent, as showed by experiments with a strict temperature control. It is largely attributed to the absorption of IRA photons of specific wavelengths by the mitochondrial CCO, causing its dissociation from the inhibitory nitric oxide (NO) and increasing oxygen consumption and ATP synthesis [35,36]. However, a full agreement in this regard does not yet exist [37].…”

Interaction between low‐level laser therapy and Guarana (Paullinia cupana) extract induces antioxidant, anti‐inflammatory, and anti‐apoptotic effects and promotes proliferation in dermal fibroblasts

“…Multiple skin conditions are treated with nonpharmacological procedures, such as low‐level laser therapy (LLLT). LLLT uses nonthermal lasers to excite endogenous chromophores, resulting in photophysical and photochemical biological events …”