Comparison of photobiomodulation in the treatment of skin injury with an open wound in mice.

This study aimed to investigate the effects of photobiomodulation at a wavelength of 660 and 830 nm at different numbers of application points in the healing of open wounds in mice. In total, 120 mice were divided into 10 groups. The animals were submitted to cutaneous lesion of the open wound type (1.5 × 1.5 cm). Photobiomodulation at a wavelength of 660 and 830 nm and total energy of 3.6 J were used, applied at 1, 4, 5, and 9 points, for 14 days. The animals were subjected to analysis of the lesion area, skin temperature, and histological analysis. Macroscopic analysis results showed a difference (p < 0.05) between the irradiated groups and the sham group at 14 days PO. There was no statistical difference in skin temperature. Histological analysis findings showed better results for the epidermis thickness. Regarding the number of blood vessels, a difference was found between the 1- and 5-point 830-nm photobiomodulation groups and between the 4-point 660-nm group and the naive group. A significant difference in the number of fibroblasts was observed between the 830- and 660-nm photobiomodulation groups and the naive and sham groups. When comparing photobiomodulation wavelength, the 830-nm groups were more effective, and we emphasize the groups irradiated at 5 points, which showed an improvement in macroscopic analysis and epidermis thickness, an increase in the number of vessels, and a lower number of fibroblasts on the 14th day after skin injury.

Photobiomodulation promotes neural regeneration when compared to simvastatin treatment in a sciatic nerve crush model.

To determine whether the effects of photobiomodulation (PBM) were associated with the use of Simvastatin in the functional recovery from sciatic nerve in mice submitted to crush injury. Fifty Swiss mice (approximately 3 months old; average weight 40 g) were randomly divided into six groups: naive, sham, control, PBM (660 nm, 10 J/cm2; 30 mW; 0.6 J per day for 28 days; 0.06 cm2; 16.8 J total and 20 s), Simvastatin (20 mg/kg), and PBM/Simv (association of the two protocols). The sciatic functional index (SFI), thermal heat hyperalgesia, mechanical hyperalgesia, and thermographic evaluation were used as analyses. The evaluations were performed preoperatively and 7, 14, 21, and 28 days after the initial injury analyzed by two-way analysis of variance (ANOVA) for mixed models followed by the Bonferroni post-test. All groups except sham and naive presented an SFI compatible with severe peripheral nerve injury on the 7th day of evaluation. The PBM group presented better results in the SFI analysis (p < 0.001) on the 21st postoperative day compared to the control group. This benefit was maintained when compared to the Simvastatin (p < 0.001) and PBM/Simv groups (p < 0.01). The results of the thermal and mechanical hyperalgesia and thermography analyses were not significant (p > 0.05). The obtained results showed that PBM alone was more effective compared to Simvastatin alone or PBM combined with Simvastatin for sciatic nerve injury in mice.

Photobiomodulation in Sciatic Nerve Crush Injuries in Rodents: A Systematic Review of the Literature and Perspectives for Clinical Treatment.

Objective : The aim of the study was to perform a literature review to analyze the effect of photobiomodulation in experimental studies on peripheral nerve regeneration after sciatic nerve crush injury in rodents. Methods: A bibliographic search was performed in the electronic databases, including MEDLINE (PubMed), SCOPUS, and SciELO, from 2008 to 2018. Results: A total of 1912 articles were identified in the search, and only 19 fulfilled all the inclusion criteria. Along with the parameters most found in the manuscripts, the most used wavelengths were 660 nm and 830 nm, power of 30 and 40 mW, and energy density of 4 and 10 J/cm2 . For total energy throughout the intervention period, the lowest energy found with positive effects was 0.70 J, and the highest 1.141 J. Seventeen studies reported positive effects on nerve regeneration. The variables selected to analyze the effect were: Sciatic Functional Index (SFI), Static Sciatic Index (SSI), morphometric, morphological, histological, zymographic, electrophysiological, resistance mechanics and range of motion (ROM). The variety of parameters used in the studies demonstrated that there is yet no pre-determined protocol for treating peripheral nerve regeneration. Only two studies by different authors used the same power, energy density, beam area, and power density. Conclusion: It was concluded that the therapeutic window of the photobiomodulation presents a high variability of parameters with the wavelength (632.8 to 940 nm), power (5 to 170 mW) and energy density (3 to 280 J /cm2 ), promoting nerve regeneration through the expression of cytokines and growth factors that aid in modulating the inflammatory process, improving morphological aspects, restoring the functionality to the animals in a brief period.

Comparative effect of photobiomodulation associated with dexamethasone after sciatic nerve injury model.

To analyze the effect of photobiomodulation and dexamethasone on nerve regeneration after a sciatic nerve crushing model. Twenty-six Swiss mice were divided into the following groups: naive; sham; injured, low-level laser therapy (LLLT) (660 nm, 10 J/cm2, 0.6 J, 16.8 J total energy emitted during the 28 days of radiation, 20 s, for 28 days); dexamethasone (Dex) (local injection of 2 mg/kg for 10 consecutive days); and LLLT group associated with Dex (LLLT/Dex), with the same parameters of the other groups. For nerve injury, a portable adjustable pinch was used. The animals were evaluated using the Sciatic Functional Index (SFI) and Sciatic Static Index (SSI). The results obtained were evaluated with Image J™ and Kinovea™. Data and images were obtained at baseline and after 7, 14, 21, and 28 days after surgery. The evaluation of hyperalgesia, using Hargreaves, and behavior through the open field was also performed. In functional and static analysis, all groups presented significant differences when compared to the injured group. In the analysis of the SSI results, the group treated with both LLLT and dexamethasone was more effective in improving the values of this parameter, and in the SFI, the laser-treated group obtained better results. In the evaluation through the open field and the Hargreaves, there was no difference. The application of LLLT and dexamethasone was effective in nerve regeneration according to the results and was more effective when LLLT was associated with dexamethasone than in LLLT alone for the SSI.