Laser biostimulation of wound healing: bioimpedance measurements support histology

Laser biostimulation in medicine has become widespread supporting the idea of therapeutic effects of photobiomodulation in biological tissues. The aim of this study was to investigate the biostimulation effect of laser irradiation on healing of cutaneous skin wounds, in vivo, by means of bioimpedance measurements and histological examinations. Cutaneous skin wounds on rats were subjected to 635 nm diode laser irradiations at two energy densities of 1 and 3 J/cm² separately. Changes in the electrical properties of the wound sites were examined with multi-frequency electrical impedance measurements performed on the 3rd, 7th, 10th, and 14th days following the wounding. Tissue samples were both morphologically and histologically examined to determine the relationship between electrical properties and structure of tissues during healing. Laser irradiations of both energy densities stimulated the wound healing process. In particular, laser irradiation of lower energy density had more evidence especially for the first days of healing process. On the 7th day of healing, 3 J/cm² laser-irradiated tissues had significantly smaller wound areas compared to non-irradiated wounds (p?<?0.05). The electrical impedance results supported the idea of laser biostimulation on healing of cutaneous skin wounds. Thus, bioimpedance measurements may be considered as a non-invasive supplementary method for following the healing process of laser-irradiated tissues.     

Photo-biomodulatory response of low-power laser irradiation on burn tissue repair in mice

The present work reports the photo-biomodulatory effect of red (632.8 nm) and near infrared (785 and 830 nm) lasers on burn injury in Swiss albino mice. Animals were induced with a 15-mm full thickness burn injury and irradiated with various fluences (1, 2, 3, 4, and 6 J/cm²) of each laser wavelength under study having a constant fluence rate (8.49 mW/cm²). The size of the injury following treatment was monitored by capturing the wound images at regular time intervals until complete healing. Morphometric assessment indicated that the group treated with 3-J/cm² fluence of 830 nm had a profound effect on healing as compared to untreated controls and various fluences of other wavelengths under study. Histopathological assessment of wound repair on treatment with an optimum fluence (3 J/cm²) of 830 nm performed on days 2, 6, 12, and 18 post-wounding resulted in enhanced wound repair with migration of fibroblasts, deposition of collagen, and neovascularization as compared to untreated controls. The findings of the present study have clearly demonstrated that a single exposure of 3-J/cm² fluence at 830-nm enhanced burn wound healing progression in mice, which is equivalent to 5 % povidone iodine treatment (reference standard), applied on a daily basis till complete healing.     

830-nm irradiation increases the wound tensile strength in a diabetic murine model

BACKGROUND AND OBJECTIVE: The purpose of this study was to investigate the effects of low-power laser irradiation on wound healing in genetic diabetes. STUDY DESIGN/MATERIALS AND METHODS: Female C57BL/Ksj/db/db mice received 2 dorsal 1 cm full-thickness incisions and laser irradiation (830 nm, 79 mW/cm(2), 5.0 J/cm(2)/wound). Daily low-level laser therapy (LLLT) occurred over 0-4 days, 3-7 days, or nonirradiated. On sacrifice at 11 or 23 days, wounds were excised, and tensile strengths were measured and standardized. RESULTS: Nontreated diabetic wound tensile strength was 0.77 +/- 0.22 g/mm(2) and 1.51 +/- 0.13 g/mm(2) at 11 and 23 days. After LLLT, over 0-4 days tensile strength was 1.15 +/- 0.14 g/mm(2) and 2.45 +/- 0.29 g/mm(2) (P = 0.0019). Higher tensile strength at 23 days occurred in the 3- to 7-day group (2.72 +/- 0.56 g/mm(2) LLLT vs. 1.51 +/- 0.13 g/mm(2) nontreated; P < or = 0.01). CONCLUSION: Low-power laser irradiation at 830 nm significantly enhances cutaneous wound tensile strength in a murine diabetic model. Further investigation of the mechanism of LLLT in primary wound healing is warranted.     

The influence of low-intensity He-Ne laser on the wound healing in diabetic rats

The low-level laser irradiation at certain wavelengths is reported to facilitate the healing process of diabetic wounds. Thus, this study carried out to look for the suitable laser parameters that could speed up the healing process. Fourteen healthy male and female rats were used in which a circular wound with a diameter of 2.5 ± 0.2 cm was created on the dorsum in each rat after injected them with alloxan to induced diabetic. They have been divided into two groups: control group (N = 7) and study group (N = 7) to conduct the study. He-Ne laser with a wavelength of 632.8 nm at power density of 4.0 mW/cm² was used to irradiate the study group for five times a week until the wound healed (closed) completely, while the control group was kept untreated. The results showed that the laser-treated group healed (wounds were totally closed) faster compared to the control group. In numbers, the laser-treated group healed on average at the 21st day (0.0 ± 0.0 cm) (P ≤ 0.005), whereas the control group healed after 40 days or even 60 days in some cases (sample no. 2). This confirms that laser promotes the tissue repair process of diabetic wounds and reduces the healing period to the half.     

Laser phototherapy improves early stage of cutaneous wound healing of rats under hyperlipidic diet

The aim of this study was to evaluate the influence of laser photobiomodulation in cutaneous healing of rats under a hyperlipidic diet. Forty-eight Wistar Albinus rats, weaned, received standard diet (SD) or hyperlipidic diet (HD) for 20 weeks. The groups were divided into SD rats and HD rats, SD-irradiated rats (LSD), and HD-irradiated rats (LHD). Standard cutaneous wound (1 cm²) was created on the dorsum of each rat. The irradiation started immediately after surgery and every 48 h for 7 or 14 days (λ660 nm, 40 mW, 6 J/cm², ? 0,04 cm², CW), when they were killed under deep anesthesia. The specimens were removed, routinely processed, stained with hematoxylin/eosin (H/E), and evaluated by light microscopy. Rats fed with hyperlipidic diet had greater intensity in the inflammatory process and prolonged hyperemia. At day 7, the intensity of inflammation was reduced in LSD and LHD groups when compared to their control groups, SD (p?=?0.002) and HD (p?=?0.02). There was an increase in fibroblast proliferation and collagen deposition, especially in the LHD group. At day 14, the HD group presented more intensive hyperemia than the SD group. It can be concluded that the hyperlipidic diet modified the inflammation pattern in wound healing and that laser light has a positive biomodulative effect on the healing process only in early stages.     

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, ? ～2 mm, 10 J/cm²); G2—laser λ790 nm (50 mW, ? ～2 mm, 10 J/cm²); G3—LED λ700?±?20 nm (15 mW, ? ～16 mm, 10 J/cm²); G4—LED λ530?±?20 nm (8 mW, ? ～16 mm, 10 J/cm²); G5—LED λ460?±?20 nm (22 mW, ? ～16 mm, 10 J/cm²). 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.     

Sub ablation effects of the KTP laser on wound healing

The KTP laser (wavelength 532 nm) was used in a sub ablative format to determine the effect of low energy density irradiation on the normal healing by primary intention of scalpel skin incisions in rats. Two longitudinal lased strips were created by a 1 cm diameter defocused beam on the shaved, cleaned dorsal epidermis of 32 Sprague-Dawley rates; one strip was produced with a 2.0 W beam (54 J, or 18 J/cm² total dose), and the other with a 3.5 W beam (94.5 J or 31.5 J/cm², total dose). Scalpel incisions were made longitudinally within the irradiated zones, using contra lateral scalpel incisions on unirradiated skin as controls. Tensio-metric analysis of wound strength was performed at 3, 7, 14, and 23 days following surgery. The data from fresh tissue tensiometry indicate that KTP laser irradiation of skin incisions results in a lower tensile strength for the wound at 7 and 14 days. The decrease in tensile strength is proportional to the total energy density of the exposure. At days 3 and 23, the tensile strength of the wound was independent of the sub ablative laser exposure. The results are in general agreement with studies of the healing process of laser incisions and may help us to understand the details of the healing process from laser incisions. © 1993 Wiley-Liss, Inc.     

Photobiomodulation of wound healing via visible and infrared laser irradiation

Fibroblast cells are known to be one of the key elements in wound healing process, which has been under the scope of research for decades. However, the exact mechanism of photobiomodulation on wound healing is not fully understood yet. Photobiomodulation of 635 and 809 nm laser irradiation at two different energy densities were investigated with two independent experiments; first, in vitro cell proliferation and then in vivo wound healing. L929 mouse fibroblast cell suspensions were exposed with 635 and 809 nm laser irradiations of 1 and 3 J/cm² energy densities at 50 mW output power separately for the investigation of photobiomodulation in vitro. Viabilities of cells were examined by means of MTT assays performed at the 24th, 48th, and 72nd hours following the laser irradiations. Following the in vitro experiments, 1 cm long cutaneous incisional skin wounds on Wistar albino rats (n = 24) were exposed with the same laser sources and doses in vivo. Wound samples were examined on 3rd, 5th, and 7th days of healing by means of mechanical tensile strength tests and histological examinations. MTT assay results showed that 635 nm laser irradiation of both energy densities after 24 h were found to be proliferative. One joule per square centimeter laser irradiation results also had positive effect on cell proliferation after 72 h. However, 809 nm laser irradiation at both energy densities had neither positive nor negative affects on cell viability. In vivo experiment results showed that, 635 nm laser irradiation of both energy densities stimulated wound healing in terms of tensile strength, whereas 809 nm laser stimulation did not cause any stimulative effect. The results of mechanical tests were compatible with the histological evaluations. In this study, it is observed that 635 nm laser irradiations of low energy densities had stimulative effects in terms of cell proliferation in vitro and mechanical strength of incisions in vivo. However, 809 nm laser irradiations at the same doses did not have any positive effect.     

The effect of He-Ne and Ga-Al-As laser light on the healing of hard palate mucosa of mice

Low-level laser therapy (LLLT) has been used to accelerate wound healing, yet questions remain concerning its therapeutic applications. This study aimed to compare the healing efficacy of helium-neon (He-Ne) red light (laser) and gallium aluminum arsenide (Ga-Al-As) infrared lasers at two different doses on hard palate wounds. In a randomized controlled study, 75 adult male mice were divided into five groups of 15 each, after undergoing identical surgical procedures; a control group, with no laser irradiation; HD1 and HD2 groups, treated with He-Ne laser (wavelengths 632.8 nm, power 5 mW, and spot size 0.02 cm²) at doses of 4 J/cm² and 7.5 J/cm² respectively; and GD1 and GD2 groups, treated with Ga-Al-As laser (wavelengths 830 nm, peak power 25 mW, and spot size 0.10 cm²) at the doses of 4 J/cm² and 7.5 J/cm², respectively. Five animals from each group were killed on the third, seventh, and 14 days after surgery, and biopsies were made for histological analysis. On the 3rd and 7th day after the surgery, the number of polymorphonuclear cells (PMN) in HD1, HD2, GD1, and GD2 groups was significantly lower than that of the control group. On the 7th and 14th day, the fibroblasts and new blood vessels counts and collagen density fibers in HD1, HD2, GD1, and GD2 groups were also significantly higher than that of the control groups, and the fibroblast counts and collagen density fibers in HD1 and HD2 groups were higher than that of the GD1 and GD2 groups. LLLT with He-Ne laser compared to Ga-Al-As laser has a positive healing effect on hard palate gingival wounds in mice regardless of the radiation dose.     

Effect of red and near-infrared wavelengths on low-level laser (light) therapy-induced healing of partial-thickness dermal abrasion in mice

Low-level laser (light) therapy (LLLT) promotes wound healing, reduces pain and inflammation, and prevents tissue death. Studies have explored the effects of various radiant exposures on the effect of LLLT; however, studies of wavelength dependency in in vivo models are less common. In the present study, the healing effects of LLLT mediated by different wavelengths of light in the red and near-infrared (NIR) wavelength regions (635, 730, 810, and 980 nm) delivered at constant fluence (4 J/cm²) and fluence rate (10 mW/cm²) were evaluated in a mouse model of partial-thickness dermal abrasion. Wavelengths of 635 and 810 nm were found to be effective in promoting the healing of dermal abrasions. However, treatment using 730- and 980-nm wavelengths showed no sign of stimulated healing. Healing was maximally augmented in mice treated with an 810-nm wavelength, as evidenced by significant wound area reduction (p?<?0.05), enhanced collagen accumulation, and complete re-epithelialization as compared to other wavelengths and non-illuminated controls. Significant acceleration of re-epithelialization and cellular proliferation revealed by immunofluorescence staining for cytokeratin-14 and proliferating cell nuclear antigen (p?<?0.05) was evident in the 810-nm wavelength compared with other groups. Photobiomodulation mediated by red (635 nm) and NIR (810 nm) light suggests that the biological response of the wound tissue depends on the wavelength employed. The effectiveness of 810-nm wavelength agrees with previous publications and, together with the partial effectiveness of 635 nm and the ineffectiveness of 730 and 980 nm wavelengths, can be explained by the absorption spectrum of cytochrome c oxidase, the candidate mitochondrial chromophore in LLLT.     

Laser light influences cellular viability and proliferation in diabetic-wounded fibroblast cells in a dose- and wavelength-dependent manner

Phototherapy stimulates metabolic processes in healing wounds. Despite worldwide interest, phototherapy is not firmly established or practiced in South Africa. This study aimed to determine which dose and wavelength would better induce healing in vitro. Diabetic-induced wounded fibroblasts were irradiated with 5 or 16 J/cm² at 632.8, 830, or 1,064 nm. Cellular morphology, viability (Trypan blue and apoptosis), and proliferation (basic fibroblast growth factor) were then determined. Cells irradiated with 5 J/cm² at 632.8 nm showed complete wound closure and an increase in viability and basic fibroblast growth factor (bFGF) expression. Cells irradiated at 830 nm showed incomplete wound closure and an increase in bFGF expression. Cells irradiated at 1,064 nm showed incomplete closure and increased apoptosis. All cells irradiated with 16 J/cm² at all three wavelengths showed incomplete wound closure, increased apoptosis, and decreased bFGF expression. This study showed that diabetic-wounded cells respond in a dose- and a wavelength-dependent manner to laser light. Cells responded the best when irradiated with a fluence of 5 J/cm² at a wavelength of 632.8 nm.     

Effect of equal daily doses achieved by different power densities of low-level laser therapy at 635 nm on open skin wound healing in normal and corticosteroid-treated rats

Optimal parameters of low-level laser therapy (LLLT) for wound healing are still discussed. Hence, our study was aimed to compare effects of different power densities of LLLT at 635 nm in rats. Four, round, full-thickness, skin wounds were made on the backs of 48 rats that were divided into two groups (non-steroid laser-treated and steroid laser-treated). Three wounds were stimulated daily with a diode laser (daily dose 5 J/cm²) each with different power density (1 mW/cm², 5 mW/cm², and 15 mW/cm²), whereas the fourth wound served as a control. Two days, 6 days, and 14 days after surgery, eight animals from each group were killed and samples were removed for histological evaluation. In the non-steroid laser-treated rats, significant acceleration of epithelization and collagen synthesis 2 days and 6 days after surgery was observed in stimulated wounds. In steroid laser-treated rats, 2 days and 14 days after surgery, a decreased leucocyte/macrophage ratio and a reduction in the area of granulation tissue were recorded, respectively. In conclusion, LLLT, by the method we used, improved wound healing in the non-steroid laser-treated rats, but it was useless after corticosteroid treatment.     

Laser irradiation affects enzymatic antioxidant system of streptozotocin-induced diabetic rats

The aim of the present study was to analyze the effect of low-power laser irradiation in the antioxidant enzymatic system of submandibular (SMG) and parotid (PG) salivary glands of streptozotocin-induced diabetic rats. The animals were randomly divided into six groups: three diabetic groups (D0, D5, and D20) and three non-diabetic groups (C0, C5, and C20), according to laser dose received (0, 5, and 20 J/cm², respectively). Areas of approximately 1 cm² were demarcated in the salivary glands (each parotid and both submandibular glands) and after irradiated according to Simões et.al. (Lasers Med Sci 24:202–208, 2009). A diode laser (660 nm/100 mW) was used, with laser beam spot of 0.0177 cm2. The group treated with 5 J/cm² laser dose was subjected to irradiation for 1 min and 4 s (total irradiation time) and the group treated with 20 J/cm² laser dose was subjected to irradiation for 4 min and 16 s. Twenty-four hours after irradiation the animals were euthanized and the salivary glands were removed for biochemical analysis. The total antioxidant values (TA), the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase enzymes were determined. SOD and CAT activities, as well as TA were higher in SMG of irradiated diabetic rats. However, in SMG of non-diabetic rats, laser irradiation decreased TA values and led to an increase in the CAT activity. In addition, there was a decrease in the activity of CAT in PG of diabetic and non-diabetic animals after laser irradiation. According to the results of the present study, low-power laser irradiation can affect the enzymatic antioxidant system of salivary glands of streptozotocin-induced diabetic rats.     

High-intensity pulsed laser irradiation accelerates bone formation in metaphyseal trabecular bone in rat femur

 Low-energy laser irradiation has positive effects on bone fracture healing, osteoblast proliferation, bone nodule formation, and alkaline phosphatase activity. However, the mechanism by which low-energy laser irradiation affects bone is not clearly known. It was recently found that light at a low radiation dosage is absorbed by intracellular chromophores. High-intensity pulsed laser irradiation can produce acoustic waves in the target surface by rapidly heating the tissue. We considered that the acoustic waves induced by high-intensity pulsed laser irradiation, in addition to the photochemical effects that are induced, accelerate bone formation. To clarify whether high-intensity pulsed laser irradiation accelerates bone formation, we investigated bone formation in the irradiated femur of rat, using histomorphometric analysis. Rat femurs were irradiated with a Q-switched Nd: YAG laser, which has a wavelength of 1064 nm, under two conditions: once a day, with the average fluence rate set at 100 mW/cm² (LA1), and twice a day, i.e., every 12 h, with the average fluence rate set at 50 mW/cm² (LA2). The mean bone volume and mineral apposition rate in the LA1 group were significantly higher than those in the nonirradiated group (control). These values were highest for the LA2 group, and were about 1.52 and 1.25-fold those of the control, respectively. These data demonstrated that the number of pulses, rather than the intensity of the laser irradiation, affects bone formation. Thus, this study indicated that high-intensity pulsed laser irradiation accelerates bone formation in the metaphysis. This bone formation induced by high-intensity pulsed laser irradiation might be due to laser-induced pressure waves. Received: May 3, 2002 / Accepted: August 8, 2002 Offprint requests to: T. Ninomiya     

Effect of Helium-Neon (He-Ne) Laser Irradiation on Dog Neoplasm Cells in Culture

The effects of laser light on the cellular proliferation have been extensively characterised. Low-power laser sources, such as the helium–neon (He-Ne) laser irradiation with a wavelength of 632.8 nm, have been found to produce photobiological and photodamaging effects with evidence of interference with cell proliferation functions. The present study has investigated the in vitro effect of He-Ne laser irradiation on the proliferative action of dog tumour cells in culture. Dose–response studies showed that repeated He-Ne irradiation (irradiance 12.8 mW/cm²) once a day for 4 consecutive days in a dose range between 0.13 and 2.08 J/cm² significantly increased with increasing energy density up to a laser dose of 0.26 J/cm², whereas at >1.04 J/cm², the cell proliferation decreased with increasing energy densities. It is concluded that the application of He-Ne laser irradiation at energy densities ranging from 0.13 J/cm² to 2.08 J/cm² produced different effects on cell proliferation in dog tumour cells in culture. Paper received for publication 27 June 1997; accepted following revision 6 February 1998.     

Effect of soft laser and bioactive glass on bone regeneration in the treatment of infra-bony defects (a clinical study)

This study aimed to investigate the influence of low-power 830 nm gallium–aluminium–arsenide (GaAlAs) laser [continuous wave (CW) 40 mW and fluence 4 J/cm², with total energy density of 16 J/cm²] on the healing of human infra-bony defects treated with bioactive glass graft material. Twenty patients with chronic periodontitis and bilateral infra-bony defects were included. Using a split mouth design, we treated 20 defects with bioactive glass plus laser irradiation during surgical procedures and on days 3, 5, 7 postoperatively; 20 contra-lateral defects were treated with bioactive glass only. Clinical probing pocket depths, clinical attachment levels and standardized periapical radiographs were recorded at baseline and at 3 months and 6 months postoperatively. At 3 months there was a statistically significant difference between the laser and non-laser sites in the parameters investigated. However, at 6 months, no difference was observed. Our results have confirmed the positive effect of soft laser in accelerating periodontal wound healing.     

Thermal imaging during photodynamic therapy (PDT)

This study was designed to measure the PDT associated changes in tumour tissue temperature and to calculate if tumoricidally relevant hyperthermia might be induced by the current clinically used PDT modalities. Syrian golden hamsters with amelanotic melanomas (A-Mel-3) received intravenous injections of Photofrin II (5 mg kg⁻¹ b.w.) or 0.9% sodium chloride (2 ml kg⁻¹ b.w.). Twenty-four hours later tumour surface and tumour centre temperature were quantified by an infra-red sensitive thermal imaging device and an implanted thermal probe during laser treatment at a wavelength of 630 nm. With laser light irradiation using power densities of 100 mW cm⁻² or 200 mW cm⁻², a significant temperature increase was noted in comparison to the baseline values. At total energy delivery of 100 J cm⁻² the tumoricidally relevant threshold of 43°C was exceeded with 200 mW cm⁻² only. However, no significant temperature differences were measured between photosensitized and control tumours receiving 100 mW cm⁻² or 200 mW cm⁻². Calculation of the corresponding applied hyperthermic dose revealed that submaximum hyperthermic effects were involved with irradiation intensities of 200 mW cm⁻².     

Should open excisions and sutured incisions be treated differently? A review and meta-analysis of animal wound models following low-level laser therapy

Although low-level laser therapy (LLLT) was discovered already in the 1960s of the twentieth century, it took almost 40 years to be widely used in clinical dermatology/surgery. It has been demonstrated that LLLT is able to increase collagen production/wound stiffness and/or improve wound contraction. In this review, we investigated whether open and sutured wounds should be treated with different LLLT parameters. A PubMed search was performed to identify controlled studies with LLLT applied to wounded animals (sutured incisions—tensile strength measurement and open excisions—area measurement). Final score random effects meta-analyses were conducted. Nineteen studies were included. The overall result of the tensile strength analysis (eight studies) was significantly in favor of LLLT (SMD?=?1.06, 95% CI 0.66–1.46), and better results were seen with 30–79 mW/cm² infrared laser (SMD?=?1.44, 95% CI 0.67–2.21) and 139–281 mW/cm² red laser (SMD?=?1.52, 95% CI 0.54–2.49). The overall result of the wound contraction analysis (11 studies) was significantly in favor of LLLT (SMD?=?0.99, 95% CI 0.38–1.59), and the best results were seen with 53–300 mW/cm² infrared laser (SMD?=?1.18, 95% CI 0.41–1.94) and 25–90 mW/cm² red laser (SMD?=?1.6, 95% CI 0.27–2.93). Whereas 1–15 mW/cm² red laser had a moderately positive effect on sutured wounds, 2–4 mW/cm² red laser did not accelerate healing of open wounds. LLLT appears effective in the treatment of sutured and open wounds. Statistical heterogeneity indicates that the tensile strength development of sutured wounds is more dependent on laser power density compared to the contraction rate of open wounds.     

Effects of low-power laser irradiation (LPLI) at different wavelengths and doses on oxidative stress and fibrogenesis parameters in an animal model of wound healing

Gallium-arsenide (GaAs) and helium-neon (HeNe) lasers are the most commonly used low-energy lasers in physiotherapy for promoting wound healing and pain modulation. The aim of this study was investigate the effect of low-power laser irradiation (LPLI) at different wavelengths and doses on oxidative stress and fibrogenesis parameters in an animal model of wound healing. The animals were randomly divided into five groups (n = 6): Controls (skin injured animals without local or systemic treatment), skin injury treated with HeNe 1 J/cm² (two seg); skin injury treated with HeNe 3 J/cm² (six seg); skin injury treated with GaAs 1 J/cm² (three seg); skin injury treated with GaAs 3 J/cm² (nine seg). A single circular wound measuring 8 mm in diameter was surgically created on the back of the animal. The rats were irradiated at 2, 12, 24, 48, 72, 96, and 120 h after skin injury. The parameters, namely hydroxyproline content, activities of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), and lipid (TBARS) and protein oxidation (carbonyl groups) measurements were assessed. In addition, wound size regression was also analyzed. The results showed an improvement in the wound healing reflected by the reduction in wound size and increased collagen synthesis. Moreover, a significant reduction in TBARS levels, carbonyl content, and SOD and CAT activities were observed after laser irradiation, particularly with the treatments HeNe laser 1 and 3 J/cm² dose and GaAs 3 J/cm² dose. The data strongly indicate that LPLI therapy is efficient in accelerating the skin wound healing process after wounding, probably by reducing the inflammatory phase and inducing collagen synthesis.     

Effect of laser and LED phototherapies on the healing of cutaneous wound on healthy and iron-deficient Wistar rats and their impact on fibroblastic activity during wound healing

Iron deficiency impairs the formation of hemoglobin, red blood cells, as well the transport of oxygen. The wound healing process involves numerous functions, many of which are dependent on the presence of oxygen. Laser has been shown to improve angiogenesis, increases blood supply, cell proliferation and function. We aimed to study the effect of λ660 nm laser and λ700 nm light-emitting diode (LED) on fibroblastic proliferation on cutaneous wounds on iron-deficient rodents. Induction of iron anemia was carried out by feeding 105 newborn rats with a special iron-free diet. A 1?×?1 cm wound was created on the dorsum of each animal that were randomly distributed into seven groups: I, control anemic; II, anemic no treatment; III, anemic?+?L; IV, anemic?+?LED; V, healthy no treatment; VI, healthy?+?laser; VII, healthy?+?LED (n?=?15 each). Phototherapy was carried out using either a diode laser (λ660 nm, 40 mW, 10 J/cm²) or a prototype LED device (λ700?±?20 nm, 15 mW, 10 J/cm²). Treatment started immediately after surgery and was repeated at 48-h interval during 7, 14, and 21 days. After animal death, specimens were taken, routinely processed, cut, stained with hematoxylin-eosin, and underwent histological analysis and fibroblast counting. Significant difference between healthy and anemic subjects on regards the number of fibroblast between treatments was seen (p?<?0.008, p?<?0.001). On healthy animals, significant higher count was seen when laser was used (p?<?0.008). Anemic subjects irradiated with LED showed significantly higher count (p?<?0.001). It is concluded that the use of LED light caused a significant positive biomodulation of fibroblastic proliferation on anemic animals and laser was more effective on increasing proliferation on non-anemics.