Angiogenesis is a key process for wound healing. There are few reports of LED phototherapy on angiogenesis, mainly in vivo. The aim of the present investigation was to evaluate histologically the angiogenesis on dorsal cutaneous wounds treated with laser (660 and 790 nm) or LEDs (700, 530, and 460 nm) in a rodent model. Twenty-four young adult male Wistar rats weighting between 200 and 250 g were used on the present study. Under general anesthesia, one excisional wound was created on the dorsum of each animal that were then randomly distributed into six groups with four animals each: G0-control; G1-laser λ660 nm (60 mW, ϕ ∼2 mm, 10 J/cm(2)); G2-laser λ790 nm (50 mW, ϕ ∼2 mm, 10 J/cm(2)); G3-LED λ700 ± 20 nm (15 mW, ϕ ∼16 mm, 10 J/cm(2)); G4-LED λ530 ± 20 nm (8 mW, ϕ ∼16 mm, 10 J/cm(2)); G5-LED λ460 ± 20 nm (22 mW, ϕ ∼16 mm, 10 J/cm(2)). Irradiation started immediately after surgery and was repeated every other day for 7 days. Animal death occurred at the eighth day after surgery. The specimens were removed, routinely processed to wax, cut and stained with HE. Angiogenesis was scored by blood vessel counting in the wounded area. Quantitative results showed that green LED (λ530 ± 20 nm), red LED (λ700 ± 20 nm), λ790 nm laser and λ660 nm laser caused significant increased angiogenesis when compared to the control group. It is concluded that both laser and LED light are capable of stimulating angiogenesis in vivo on cutaneous wounds and that coherence was not decisive on the outcome of the treatment.

The aim of the present investigation was to evaluate the angiogenesis on dorsal cutaneous wounds in a rodent model treated with λ660 nm laser light. New vessel formation is a multistep process involving vessel sprouting, endothelial cell migration, proliferation and tube formation. Although several in vivo studies have shown that laser phototherapy influences tissue repair, a fully understanding of angiogenesis mechanisms are not yet known. Twenty-four young adult male Wistar rats weighing between 200 and 250 g were used. Under general anesthesia, one excisional wound was created on the dorsum of each animal and they were randomly distributed into two groups: one control and one treated with laser (λ660 nm, 16 mW, 10 J/cm2). Each group was subdivided into three subgroups according to the animal death timing (2, 4 and 6 days). Laser irradiation started immediately after surgery and was repeated every other day during the experiment and marked with Sirius Red, specific for collagen, and immunomarked with anti-TGF-β and anti-von Willebrand factor. Marked sections underwent histological analysis by light microscopy and the mean area of the wound of each animal was calculated and analyzed by ANOVA and Tukey's test (α=0.05). Although at some death periods, collagen expression and number of blood vessels on irradiated animals were higher than in the control ones, no significant differences were found at any time in relation to TGF-β expression (p>0.05). It was concluded that laser treatment (λ660 nm) contributed to increase angiogenesis.

The use of green and red LED light is effective in increasing fibroblastic proliferation on rodents.

LPT was effective in increasing angiogenesis as seen on irradiated subjects and was more pronounced when IR laser light was used.

Laser and LED phototherapies accelerate tissue repair. Mast cells induce the proliferation of fibroblasts and the development of local fibrosis. Increased numbers of myofibroblasts and mast cells are frequently found together in a normal wound repair, suggesting that mediators produced by the mast cells could play a role in the regulation of myofibroblast differentiation and function. The aim of this study was to analyze the involvement of mast cells on the synthesis of collagen and their influence on myofibroblast differentiation in the late phase of tissue repair on wounds treated with LLLT (λ 660 nm, 10 J/cm(2), 40 mW, 252 s) or LED (λ 630 ± 10 nm, 10 J/cm(2), 115 mW, 87 s). A 1 × 1-cm surgical wound was created on the dorsum of 30 rats divided into three groups of ten animals each: control, laser, and LED. The animals of each group were irradiated and sacrificed 7 and 14 days after injury. The statistical analysis was performed using the Mann-Whitney and Spearman correlation tests. Laser light improved the collagen deposition rate along the time points (p = 0.22), but when compared to the control groups during the periods studied, the number of mast cells decreased significantly (p ≤ 0.05). With respect to myofibroblasts, the results showed a trend to their reduction. No statistical significances were observed for LED light according to the parameters used in this study. It is concluded that the mast cell and myofibroblast population might participate in the collagen formation of irradiated wounds particularly in relation to laser phototherapy.