Infrared LED light therapy influences the expression of fibronectin and tenascin in skin wounds of malnourished rats--a preliminary study.

The aim of this investigation was to evaluate the effect of infrared (λ 846±20nm) LED irradiation on the expression profile of the extracellular matrix protein components, tenascin and fibronectin on skin wounds induced in well nourished and malnourished rats. Eighteen albino rats (21 days old) were randomly divided into a well-nourished group (standard diet) and a malnourished group (regional basic diet). After receiving the diet for 70 days, skin wounds were created and the animals were subdivided into three groups: well-nourished control (n=6), malnourished control (n=6), and malnourished+LED irradiated (λ 846±20nm, 100mW, 4J/cm(2)) (n=6). The animals were sacrificed 3 and 7 days after injury and histological sections were immunostained for both proteins. They were examined for the presence, intensity, distribution and pattern of immunolabeling. At 3 days, the distribution of tenascin was shown to be greater in the wound bed of malnourished animals compared to the well-nourished group. The intensity and distribution of tenascin was shown to be lower in the malnourished LED irradiated group compared to the malnourished control. There was a significant difference regarding the presence of fibronectin in the malnourished and well-nourished groups after 7 days (p=0.03). The intensity of fibronectin was slight (100%) in the irradiated group and moderate to intense in the malnourished control group. The results of the present study indicate that infrared LED irradiation modulates positively the expression of tenascin and particularly fibronectin.

Laser and LED phototherapies on angiogenesis.

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.

Effect of LED phototherapy (λ700 ± 20 nm) on TGF-ß expression during wound healing: an immunohistochemical study in a rodent model.

OBJECTIVE: The aim of the present investigation was to evaluate transforming growth factor ß (TGF-ß) expression on cutaneous wounds in rodents treated or not treated with LED light. BACKGROUND: TGF-ß is a multifunctional cytokine that presents a central action during tissue repair. Although several studies both in vitro and in vivo have shown that LED phototherapy influences tissue repair, a full understanding of the mechanisms involved in its usage, such as in the modulation of some growth factors, remains unclear. MATERIALS AND METHODS: Under general anesthesia, 24 young adult male Wistar rats weighing 200-250 g had one excisional wound created on the dorsum of each, and were randomly distributed into two groups: G0 (Control) and G1 (LED, λ700 ± 20 nm, 16 mW, SAEF = 5 J/cm(2), Illuminated Area = 2 cm(2), 8 mWcm(2), 626 s) Each group was subdivided into three subgroups according to the animal death timing (2, 4, and 6 days). LED phototherapy started immediately after surgery and was repeated every other day during the experimental time. Following animal death, specimens were removed, routinely processed to wax, cut and immunomarked with polyclonal anti-TGF-ß, and underwent histological analysis by light microscopy. The mean area of expression of each group was calculated. The data were statistically analyzed using ANOVA and Tukey's test. RESULTS: The area of the expression of TGF-ß on LED-irradiated animals was significantly smaller than on controls at day 2 (p = 0.013). No significant difference was found at later times. It is concluded that the use of LED light, at these specific parameters, caused an inhibition of the expression of TGF-ß at an early stage of the healing process.

Effect of LED phototherapy of three distinct wavelengths on fibroblasts on wound healing: a histological study in a rodent model.

AIM: The aim of the present investigation was to evaluate histologically fibroblastic proliferation on dorsal cutaneous wounds in a rodent model treated or not with light-emitting diodes (LEDs) of three wavelengths. BACKGROUND: Fibroblasts secrete substances essential for wound healing. There are few reports of LED phototherapy on fibroblast proliferation, mainly in vivo. ANIMALS AND METHODS: Following approval by the Animal Experimentation Committee of the School of Dentistry of the Federal University of Bahia, we obtained 16 young adult male Wistar rats weighing between 200 and 250 g. Under general anesthesia, one excisional wound was created on the dorsum of each animal; they were then randomly distributed into four groups of four animals each: G0, untreated control; G1, red LED (700 +/- 20 nm, 15 mW, 10 J/cm(2)); G2, green LED (530 +/- 20 nm, 8 mW, 10 J/cm(2)); and G3, blue LED (460 +/- 20 nm, 22 mW, 10 J/cm(2)). The irradiation started immediately after surgery and was repeated every other day for 7 days. Animals were killed 8 days after surgery. The specimens were removed, routinely processed to wax, cut, and stained with hematoxylin/eosin (HE). Fibroblasts were scored by measuring the percentage of these cells occupying the area corresponding to wound healing on stained sections. RESULTS: The quantitative results showed that red LED (700 +/- 20 nm) and green LED (530 +/- 20 nm) showed a significant increase in fibroblast numbers (p < 0.01 and p = 0.02) when compared with the control group. CONCLUSION: The use of green and red LED light is effective in increasing fibroblastic proliferation on rodents.