The aim of this study was to compare the effectiveness of low-intensity LED radiation of the red and infrared spectra for the correction of mucositis in patients receiving radiation and chemoradiation therapy for oral and pharyngeal cancer at an energy density of less than 1 J/cm2. The study included 106 patients who received radiation and chemoradiation therapy for oral cavity and pharyngeal cancer, who were randomly divided into three groups. In the first (37 patients) correction of mucositis was carried out in accordance with the clinic's standards, in the second (36 patients) and the third (33 patients), patients additionally received exposure to the oral cavity with low-intensity LED radiation at a wavelength of 635 nm at a dose of 0,3 J/cm2 (prophylactic regimen) and 0.45 J/cm2 (treatment regimen). When exposed to a wavelength of 780 nm, the dose was 0.6 J/cm2 with a prophylactic regime and 0.8 J/cm2 with a therapeutic regimen, respectively. Exposure to low-level LED irradiation at a wavelength of 635 nm significantly reduced the frequency and severity of radiation mucositis, increased the time until the onset of its first symptoms, reduced the duration of severe mucositis (grade 3) and reduced the patients' need for painkillers, including narcotic analgesics compared with the group receiving standard prophylaxis and correction of mucositis. Photobiomodulation at a wavelength of 780 nm, compared with the standard correction group, significantly increased the time to the onset of the first symptoms of mucositis and decreased the severity of pain.
The aim of the work was studying the effects of photobiomodulation in doses of less than 1 J/cm2 in combination with gamma-irradiation to Hela Kyoto cells. Tumor cells were irradiated with 640 nm LED at different energy densities before and after to gamma-irradiation. Cells viability was determined 24 h after exposure for each gamma-irradiation dose and PBM mode. There was a statistically significant decrease in a number of viable tumor cells for samples that were exposed to PBM prior to gamma-irradiation and a statistically significant increase in a number of viable tumor cells for samples that were exposed to PBM after gamma-irradiation.
Significance: Currently, various scaffolds with immobilized cells are widely used in tissue engineering and regenerative medicine. However, the physiological activity and cell viability in such constructs might be impaired due to a lack of oxygen and nutrients. Photobiomodulation (PBM) is a promising method of preconditioning cells to increase their metabolic activity and to activate proliferation or differentiation.
Aim: Investigation of the potential of PBM for stimulation of cell activities in hydrogels.
Approach: Mesenchymal stromal cells (MSCs) isolated from human gingival mucosa were encapsulated in modified fibrin hydrogels with different thicknesses and concentrations. Constructs with cells were subjected to a single-time exposure to red (630 nm) and near-infrared (IR) (840 nm) low-intensity irradiation. After 3 days of cultivation, the viability and physiological activity of the cells were analyzed using confocal microscopy and a set of classical tests for cytotoxicity.
Results: The cell viability in fibrin hydrogels depended both on the thickness of the hydrogels and the concentration of gel-forming proteins. The PBM was able to improve cell viability in hydrogels. The most pronounced effect was achieved with near-IR irradiation at the 840-nm wavelength.
Conclusions: PBM using near-IR light can be applied for stimulation of MSCs metabolism and proliferation in hydrogel-based constructs with thicknesses up to 3 mm.
Photobiomodulation (PBM) using nonionizing light sources, including lasers, light-emitting diodes, and/or broadband light, in the visible (400 to 700 nm) and near-infrared (700 to 1100 nm) electromagnetic spectrum, has been successfully exploited for multiple therapeutic purposes. We analyzed the effects of red and infrared irradiation on neuroblastoma cells in an in vitro rotenone model of Parkinson’s disease. Cell viability was assessed by colorimetric assay for metabolic activity (MTT test), and the oxygen consumption rate was analyzed using a Seahorse analyzer. Low doses of rotenone slightly, but not significantly, suppressed oxygen consumption and did not affect cell viability within 2 hours of treatment. PBM stimulated mitochondrial respiration overcoming rotenone-induced inhibition. At high doses (50 μM), rotenone moderately suppressed cell viability, which was reversed by PBM. Thus, preliminary treatment with red and infrared radiation improves cell viability and enhances mitochondrial oxygen consumption in an in vitro rotenone model of Parkinson’s disease.
Mesenchymal stem cells (MSCs) represent a significant interest for cell therapy applications and, being primary cells, undergo gradual aging in culture. We studied the effects of low-intensity infrared laser irradiation during aging of MSCs in culture. Both young and aged MSCs respond to low irradiation doses (0.17 J / cm2) by growth activation and to middle doses (2.1 J / cm2) by growth retardation. Aged cells demonstrate a relatively higher growth response to low doses, but they are significantly more susceptible to deleterious effects of middle doses compared to young cells. Studies of MSC aging during long-term culture under hypoxia conditions demonstrate that low-dose irradiation of MSCs every 2 days in culture substantially increases the number of population doublings, compared to the control group. In addition, irradiated cells persisted in culture for two passages (4 days) longer than their control counterparts. However, irradiated cells did not proliferate more rapidly if irradiation was omitted. We conclude that growth responses of young and aged murine MSCs to infrared laser irradiation differ significantly and that regular irradiation affects MSC aging in culture but does not result in a bonafide retardation of aging process.
Light field intensity distribution in three-dimensional polylactide scaffolds after irradiation with low-intensity light from one side of the samples has been determined in the visible and near-infrared regions of the spectrum. Two different types of scaffolds manufactured by the methods of supercritical fluid foaming and surface selective laser sintering have been investigated. The problem is solved by numerical calculation according to the Monte Carlo method involving experimentally obtained information about effective optical parameters of the scaffold material. Information about intensity distribution of the incident light in the matrix volume is needed to assess the radiation level for the scaffold cells after photobiostimulation. It has been shown that the formation of the light field in case of strongly scattering media, such as polylactide scaffolds, is determined by anisotropy g and the scattering coefficient μs.
The bleaching of polyacrylamide tattooed skin-mimicking phantoms by a series of laser pulses in a single session is studied. It is shown that compared to the single-pulse procedures tattoo removal by series of laser pulses allows not only for reducing the necessary laser fluence, but also for improving the degree of bleaching. The dynamics of formation and dissolution of microscopic gas bubbles in tattooed skin phantoms exposed to laser radiation is also studied. A laser-induced tattoo bleaching mechanism is suggested, based on the process of selective photo-thermolysis of pigmented particles in conditions where the thermal conductivity of the medium surrounding the particles is decreased because of the microbubbles formed therein.