Differing energy densities with laser 670 nm InGaP controls inflammation and collagen reorganization in burns

•Low-level laser InGaP670 nm promoted beneficial modulation effects on burn.•Energy densities of 4.93 J/cm2 and 9.86 J/cm2 of laser benefited the repair of burns.•The 9.86 J/cm2 energy density was more effective in decreasing inflammation and collagen reorganization.

PurposeThis study compared different energy densities of laser on second degrees burns in rats aiming to determine the most effective dosimetry in stimulation of the healing process.MethodsBurns were induced in the dorsal skin of 54 animals divided into three groups (n: 18): 1-without treatment; 2-irradiated lesions by the Indium Gallium Phosphide (InGaP) 670 nm (4.93 J/cm2) laser; 3-irradiated lesions by the InGaP-670 nm (9.86 J/cm2) laser. Samples were collected on the 2, 10 and 18 days after injury for structural, morphometry, biochemical analysis and Western blotting.ResultsThe energy densities examined were effective in significantly increasing the total number of fibroblasts and blood vessels and reduce the number of inflammatory cells particularly in irradiated lesions with 9.86 J/cm2. This same energy density significantly increased the amount of GAGs (Glycosaminoglycans), decreased the TGF-β1 (Transforming Growth Factor β1) and increased the VEGF (Vascular and Endothelial Growth Factor) during the experimental period. This energy density also significantly increased the Collagen type I and decreased Collagen type III and the active isoform of metalloproteinase 9 (MMP-9).ConclusionsThe energy density of 9.86 J/cm2 was more effective in promoting cellular responses related to neoangiogenesis, decreasing inflammation and collagen fibers reorganization.