Low-level laser therapy induces human umbilical vascular endothelial cell proliferation, migration and tube formation through activating the PI3K/Akt signaling pathway.

Low-level laser therapy (LLLT) has been recognized as a light therapy that may be used for tissue regeneration, inflammation reduction, and pain relief. We intended to evaluate the effects of LLLT on the proliferation, migration, and tube formation of HUVECs as well as their related mechanisms. HUVECs were exposed to laser irradiation under different laser parameters (irradiation dose, interval and power intensity) in order to choose the optimal parameters, which were determined by the increase in proliferation of HUVECs as follows: irradiation dose of 4.0 J/m2, interval time of 12 h and 6 times in total. The HUVEC proliferation, migration, and tube formation, and levels of angiogenesis-related genes (HIF-1α, eNOS and VEGFA) were examined following LLLT. As suggested by the obtained data, LLLT (1.0, 2.0 and 4.0 J/m2) increased the HUVEC proliferation, migration, and tube formation in dose-and time-dependent manner, accompanied with increases in the levels of HIF-1α, eNOS, and VEGFA. Furthermore, the regulatory mechanism regarding the phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) signaling pathway was explored, phosphorylation levels of PI3K and Akt proteins were assessed by Western blot assay, which showed the enhancement of phosphorylation of PI3K, Akt, and mTOR by LLLT. The inhibitor for the PI3K/Akt axis was used to verify the involvement of PI3K/Akt signaling pathway. The obtained results suggested that the inhibition of the PI3K/Akt signaling pathway attenuated the effects of LLLT on proliferation, migration, and angiogenesis of HUVECs. In conclusion, LLLT promotes the proliferation, migration, and angiogenesis of HUVECs via activation of the PI3K/Akt signaling pathway.

Photobiomodulation of red and green lights in the repair process of third-degree skin burns.

The aim of this study was to evaluate the photobiomodulation of red and green lights in the repair process of third-degree skin burns in rats through clinicopathological and immunohistochemical parameters. Sixty male Wistar rats were divided into three groups: control (CTRL) (n = 20), red LED (RED) (n = 20), and green LED (GREEN) (n = 20), with subgroups (n = 5) for each time of euthanasia (7, 14, 21, and 28 days). Daily applications in RED (λ630 ± 10 nm, 300 mW) and GREEN groups (λ520 ± 30 nm, 180 mW) were performed at four points of the wound (total 36 J/cm2 in RED and 240 J/cm2 in GREEN). After euthanasia, the wound retraction index (WRI) was evaluated. In histological sections, the re-epithelialization degree, the angiogenic index (AI), and the amount of myofibroblasts in wounds were analyzed. At 14 and 21 days, the RED group induced higher re-epithelialization and WRI compared to CTRL (p > 0.05) and GREEN groups (p < 0.05). At 7 and 14 days, greater AI were observed in the GREEN group, with significant difference in relation to CTRL group at 7 days (p < 0.05). At 21 and 28 days, a trend was observed for greater amount of myofibroblasts in the GREEN group, with significant difference in relation to CTRL group at 21 days (p < 0.05). The results suggest greater potential of the green light to stimulate angiogenesis in the initial periods and myofibroblastic differentiation in the final periods of the repair of third-degree skin burns. Red light may stimulate further re-epithelialization and wound retraction, especially in advanced repair phases.

Stereological and gene expression examinations on the combined effects of photobiomodulation and curcumin on wound healing in type one diabetic rats.

We examined the effects of photobiomodulation (PBM) independently and combined with curcumin on stereological parameters and basic fibroblast growth factor (bFGF), hypoxia-inducible factor-1α (HIF-1α), and stromal cell-derived factor-1α (SDF-1α) gene expressions in an excisional wound model of rats with type one diabetes mellitus (T1DM). T1DM was induced by an injection of streptozotocin (STZ) in each of the 90 male Wistar rats. One round excision was generated in the skin on the back of each of the 108 rats. The rats were divided into six groups (n = 18 per group): control (diabetic), untreated group; vehicle (diabetic) group, which received sesame oil; PBM (diabetic) group; curcumin (diabetic) group; PBM + curcumin (diabetic) group; and a healthy control group. On days 4, 7, and 15, we conducted both stereological and quantitative real-time PCR (qRT-PCR) analyses. The PBM and PBM + curcumin groups had significantly better inflammatory response modulation in terms of macrophages (P < .01), neutrophils (P < .001), and increased fibroblast values compared with the other groups at day 4 (P < .001), day 7 (P < .01), and day 15 (P < .001). PBM treatment resulted in increased bFGF gene expression on days 4 (P < .001) and 7 (P < .001), and SDF-1α gene expression on day 4 (P < .001). The curcumin group had increased bFGF (P < .001) expression on day 4. Both the PBM and PBM + curcumin groups significantly increased wound healing by modulation of the inflammatory response, and increased fibroblast values and angiogenesis. The PBM group increased bFGF and SDF-1α according to stereological and gene expression analyses compared with the other groups. The PBM and PBM + curcumin groups significantly increased the skin injury repair process to more rapidly reach the proliferation phase of the wound healing in T1DM rats.

Low-level laser therapy affects dentinogenesis and angiogenesis of in vitro 3D cultures of dentin-pulp complex.

To investigate the effects of gallium-aluminum-arsenide (GaAlAs) diode laser low-level laser therapy (LLLT) on angiogenesis and dentinogenesis of the dentin-pulp complex in a human tooth slice-based in vitro model. Forty tooth slices were prepared from 31 human third molars. Slices were cultured at 37 °C, 5% CO2, and 95% humidity and randomly assigned to one of the following groups: group I: no laser treatment, group II: 660-nm diode laser; energy density = 1 J/cm2, group III: 660-nm diode laser; energy density = 3 J/cm2, group IV: 810-nm diode laser; energy density = 1 J/cm2 and group V: 810-nm diode laser; energy density = 3 J/cm2. LLLT was applied on the third and fifth days of culture. After 7 days, tissues were retrieved for real-time RT-PCR analysis to investigate the expression of VEGF, VEGFR2, DSPP, DMP-1, and BSP in respect to controls. Lower energy density (1 J/cm2) with the 660 nm wavelength showed a statistically significant up-regulation of both angiogenic (VEGF: 15.3-folds and VEGFR2: 3.8-folds) and odontogenic genes (DSPP: 6.1-folds, DMP-1: 3-fold, and BSP: 6.7-folds). While the higher energy density (3 J/cm2) with the 810 nm wavelength resulted in statistically significant up-regulation of odontogenic genes (DSPP: 2.5-folds, DMP-1: 17.7-folds, and BSP: 7.1-folds), however, the angiogenic genes had variable results where VEGF was up-regulated while VEGFR2 was down-regulated. Low-level laser therapy could be a useful tool to promote angiogenesis and dentinogenesis of the dentin-pulp complex when parameters are optimized.

Low level laser therapy (LLLT) modulates ovarian function in mature female mice.

It is known that LLLT has beneficial effects on several pathological conditions including wound healing, pain and inflammation. LLLT modulates biological processes, including cell proliferation, apoptosis and angiogenesis. In the present study, we examined the effect of local application of LLLT on follicular dynamics, ovarian reserve, AMH expression, progesterone levels, apoptosis, angiogenesis, and reproductive outcome in adult mice. LLLT (200 J/cm2) increased the percentage of primary and preantral follicles, whilst decreasing the percentage of corpora lutea compared to control ovaries. LLLT-treated ovaries did not exhibit any changes regarding the number of primordial follicles. We observed a higher percentage of AMH-positive follicles (in early stages of development) in LLLT-treated ovaries compared to control ovaries. LLLT reduced the P4 concentration and the apoptosis in early antral follicles compared to control ones. LLLT caused a reduction in the endothelial cell area and an increase in the periendothelial cell area in the ovary. Additionally, LLLT was able to improve oocyte quality. Our findings suggest that local application of LLLT modulates follicular dynamics by regulating apoptosis and the vascular stability in mouse ovary. In conclusion, these data indicate that LLLT might become a novel and useful tool in the treatment of several pathologies, including female reproductive disorders.

Effect of blue LED on the healing process of third-degree skin burns: clinical and histological evaluation.

The aim of this study was to evaluate the effects of blue light-emitting diode (LED) on the healing process of third-degree skin burns in rats through clinical and histological parameters. Forty male Wistar rats were divided into two groups: control (CTR) (n = 20) and blue LED (BLUE) (n = 20), with subgroups (n = 5) for each time of euthanasia (7, 14, 21, and 28 days). LED (470 nm, 1 W, 12.5 J/cm2 per point, 28 s) was applied at four points of the wound (total, 50 J/cm2). Feed intake was measured every other day. It was observed that there were no statistically significant differences in the Wound Retention Index (WRI) of the BLUE group in relation to CTR group (p > 0.05) at the evaluation times. After 14, 21, and 28 days, it was observed that the animals in the BLUE group consumed more feed than animals in the CTR group (p < 0.05). At 7 days, there was a statistically significant increase in the angiogenic index (AI) in BLUE (median: 6.2) when compared to CTR (median: 2.4) (p = 0.01) and all animals in BLUE had already started re-epithelialization. This study suggests that blue LED, at the dosimetry used, positively contributed in important and initial stages of the healing process of third-degree skin burns.

Photobiomodulation of freshly isolated human adipose tissue-derived stromal vascular fraction cells by pulsed light-emitting diodes for direct clinical application.

A highly interesting source for adult stem cells is adipose tissue, from which the stromal vascular fraction (SVF)-a heterogeneous cell population including the adipose-derived stromal/stem cells-can be obtained. To enhance the regenerative potential of freshly isolated SVF cells, low-level light therapy (LLLT) was used. The effects of pulsed blue (475 nm), green (516 nm), and red (635 nm) light from light-emitting diodes applied on freshly isolated SVF were analysed regarding cell phenotype, cell number, viability, adenosine triphosphate content, cytotoxicity, and proliferation but also osteogenic, adipogenic, and proangiogenic differentiation potential. The colony-forming unit fibroblast assay revealed a significantly increased colony size after LLLT with red light compared with untreated cells, whereas the frequency of colony-forming cells was not affected. LLLT with green and red light resulted in a stronger capacity to form vascular tubes by SVF when cultured within 3D fibrin matrices compared with untreated cells, which was corroborated by increased number and length of the single tubes and a significantly higher concentration of vascular endothelial growth factor. Our study showed beneficial effects after LLLT on the vascularization potential and proliferation capacity of SVF cells. Therefore, LLLT using pulsed light-emitting diode light might represent a new approach for activation of freshly isolated SVF cells for direct clinical application.

Enhanced survival of ischemic skin flap by combined treatment with bone marrow-derived stem cells and low-level light irradiation.

The aim of this study is to examine the enhanced survival effect of ischemic skin flap by combined treatment with bone marrow-derived stem cells (BMSCs) and low-level light irradiation (LLLI). The neovasculogenic effect of BMSCs induced by LLLI was detected using a wound healing and tube formation assay. ICR mice were divided into four groups: control group, LLLI group, BMSCs group, and combine-treated group. The percentage of skin flap necrosis area was calculated on the seventh post-operative day. Specimens were harvested for histologic analyses. LLLI promoted BMSC migration and tube formation. The flap survival rate of combined treated group was significantly higher than that of the control group. Histologic results demonstrated a significant increase in neovascularization in the combined treatment group. This study demonstrates that combination treatment of BMSCs and LLLI could enhance the survival of ischemic skin flap in a mouse model.

The effects of low-level laser therapy on the healing of bone defects in streptozotocin-induced diabetic rats: A histological and morphometric evaluation.

BACKGROUND: The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) on the healing of bone defects in rats with streptozotocin (STZ)-induced DM. METHODS: 28 male Sprague-Dawley rats were used in this study. 14 animals received a single dose of STZ intraperitoneally (65 mg/kg) to induce Type I DM, whereas others were injected only with sterile saline solution. Four weeks later, standard bone defects were created in the tibiae of rats. Surgical wounds in one group from each of the diabetic and non-diabetic animals were irradiated with diode laser for every other day for 4 weeks and they were described as DM + LLLT and CONT + LLLT groups, respectively. Remaining two groups received no laser treatment. New bone formation, osteoblast and blood vessel counts were calculated in histologic sections. RESULTS: DM group had significantly smaller bone area and lower blood vessel count when compared to DM + LLLT, CONT and CONT + LLLT groups (p < 0.05 for each). CONT and CONT + LLLT groups had significantly larger bone area than DM + LLLT group (p < 0.05 for both). CONCLUSIONS: LLLT application promoted vascularization and new bone formation in animals with DM to a limited extent, since it was unable to support the healing process up to the level of non-diabetic animals.

Human adipose-derived stem cell spheroid treated with photobiomodulation irradiation accelerates tissue regeneration in mouse model of skin flap ischemia.

Skin flap grafting is a form of transplantation widely used in plastic surgery. However, ischemia/reperfusion injury is the main factor which reduces the survival rate of flaps following grafting. We investigated whether photobiomodulation (PBM) precondition prior to human adipose-derived stromal cell (hASC) spheroid (PBM-spheroid) transplantation improved skin tissue functional recovery by the stimulation of angiogenesis and tissue regeneration in skin flap of mice. The LED had an emission wavelength peaked at 660 ± 20 nm (6 J/cm2, 10 mW/cm2). The expression of angiogenic growth factors in PBM-spheroid hASCs was much greater than that of not-PBM-treated spheroid or monolayer-cultured hASCs. From immunochemical staining analysis, the hASCs of PBM-spheroid were CD31+, KDR+, and CD34+, whereas monolayer-cultured hASCs were negative for these markers. To evaluate the therapeutic effect of hASC PBM-spheroid in vivo, PBS, monolayer-cultured hASCs, and not-PBM-spheroid were transplanted into a skin flap model. The animals were observed for 14 days. The PBM-spheroid hASCs transplanted into the skin flap ischemia differentiated into endothelial cells and remained differentiated. Transplantation of PBM-spheroid hASCs into the skin flap ischemia significantly elevated the density of vascular formations through angiogenic factors released by the skin flap ischemia and enhanced tissue regeneration at the lesion site. Consistent with these results, the transplantation of PBM-spheroid hASCs significantly improved functional recovery compared with PBS, monolayer-cultured hASCs, and not-PBM-spheroid treatment. These findings suggest that transplantation of PBM-spheroid hASCs may be an effective stem cell therapy for the treatment of skin flap ischemia.

Laser photobiomodulation (830 and 660 nm) in mast cells, VEGF, FGF, and CD34 of the musculocutaneous flap in rats submitted to nicotine.

The aim of this study was to investigate the effect of laser photobiomodulation (PBM) on the viability of the transverse rectus abdominis musculocutaneous (TRAM) flap in rats subjected to the action of nicotine. We evaluated 60 albino Wistar rats, divided into six groups of ten animals. Group 1 (saline) underwent the surgical technique to obtain a TRAM flap; group 2 (laser 830 nm) underwent the surgical technique and was irradiated with a laser 830 nm; group 3 (laser 660 nm) underwent the surgical technique and was irradiated with a laser 660 nm; group 4 was treated with nicotine subcutaneously (2 mg/kg/2×/day/4 weeks) and underwent surgery; group 5 (nicotine + laser 830 nm) was exposed to nicotine, underwent the surgical technique, and was irradiated with a laser 830 nm; group 6 (nicotine + laser 660 nm) was exposed to nicotine, underwent the surgical technique, and was irradiated with a laser 660 nm. The application of PBM occurred immediately after surgery and on the two following days. The percentage of necrosis was assessed using the AxioVision® software. The number of mast cells (toluidine blue staining) was evaluated, and immunohistochemistry was performed to detect vascular endothelial growth factor expression (anti-VEGF-A), fibroblasts (anti-basic FGF), and neoformed vessels (anti-CD34). PBM with a wavelength of 830 nm increased the viability of the TRAM flap, with a smaller area of necrosis, increased number of mast cells, and higher expression of VEGF and CD34. PBM increases the viability of musculocutaneous flaps treated with to nicotine.

Photobiomodulation regulates cytokine release and new blood vessel formation during oral wound healing in rats.

The aim of the present study was to evaluate the effects of photobiomodulation (PBM) on cytokine levels and angiogenesis during oral wound healing. Ulcers were made on the dorsum of the tongue in 48 Wistar rats. Irradiation with an indium-gallium-aluminum-phosphide (InGaAlP) laser (660 nm; output power, 40 mW; spot size, 0.04 cm(2)) was performed once a day on two points of the ulcer for 14 days. Two different energy densities were used: 4 J/cm(2) (energy per point 0.16 J, total energy 0.32 J) and 20 J/cm(2) (energy per point 0.8 J, total energy 1.6 J). Tissue levels of interleukin (IL)-1ß and tumor necrosis factor (TNF)-α were investigated by enzyme-linked immunosorbent assay (ELISA). Image analysis of CD31-immunostained sections was used to investigate microvessel density (MVD). PBM increased the tissue levels of IL-1ß at the early stage of oral wound healing (p < 0.01) and increased the tissue levels of TNF-α during all stages of oral wound healing (p < 0.05). PBM at a dose of 4 J/cm(2) produced more significant results regarding cytokine modulation and was associated with higher MVD at day 5. Collectively, these findings indicate that cytokine modulation and increased angiogenesis are among the basic mechanisms whereby PBM improves oral wound repair.

Use of low-power laser to assist the healing of traumatic wounds in rats.

PURPOSE: To investigate the morphological aspects of the healing of traumatic wounds in rats using low-power laser. METHODS: Twenty four non isogenic, young adult male Wistar rats (Rattus norvegicus) weighing between 200 and 300 g was used. The animals were randomly distributed into two groups: Control (GC) and Laser (GL), with 12 animals each. After shaving, anesthesia was performed in the dorsal region and then a surgical procedure using a scalpel was carried out to make the traumatic wound. GL received five sessions of laser therapy in consecutive days using the following laser parameters: wavelength 660 nm, power 100 mW, dose 10 J/cm2. The wounds were evaluated through measurement of the area and depth of the wound (MW) and histological analysis (HA). RESULTS: When comparing the GC with the GL in MW there was a difference in area (p<0.001) and depth (p=0.003) measurement of the wounds in GL. The laser group presented more epithelization than GC (p=0.03). The other histological parameters were similar. CONCLUSION: The healing of wounds in rats was improved with the use of the laser.

InGaP 670-nm laser therapy combined with a hydroalcoholic extract of Solidago chilensis Meyen in burn injuries.

Therapies that accelerate the healing of burn injuries, improving the quality of life of the patient and reducing the cost of treatment are important. This study evaluated the effects of InGaP 670-nm laser therapy combined with a hydroalcoholic extract of Solidago chilensis leaves on burn wound healing in rats. Seventy-two rats were divided randomly into four groups: control untreated (C), treated with InGaP 670-nm laser with power density of 0.41 W/cm(2) and energy density of 4.93 J/cm(2) (L), treated with S. chilensis extract (S) and treated with S. chilensis extract and laser (LS). Second-degree burns were produced on the back of the animals with metal plate. Wound samples were collected on days 7, 14 and 21 of treatment for structural analysis, morphometry and Western blotting to quantify the expression of transforming growth factor beta 1 (TGF-ß1) and vascular endothelial growth factor (VEGF). The results showed that InGaP laser irradiation at 670 nm alone and combined with extract of S. chilensis promoted significant tissue repair responses in this experimental model, increasing the number of fibroblasts, collagen fibres and newly formed blood vessels throughout the experimental period and decreasing the number of granulocytes in burn wounds of second degree in all treated groups. Exclusive treatment of burn wounds with the hydroalcoholic extract of S. chilensis provided similar quantitative results to those seen in the untreated group throughout the experimental period. Therefore, it was observed in the L and LS groups different responses in the expression of TGF-ß1 and VEGF. The application of 670-nm laser alone or combined with the extract of S. chilensis promoted favourable responses in tissue repair of second-degree burns in this experimental model.

Low level light therapy by LED of different wavelength induces angiogenesis and improves ischemic wound healing.

BACKGROUND AND OBJECTIVE: Low-level light therapy (LLLT) has been revealed as a potential means to improve wound healing. So far, most studies are being performed with irradiation in the red to near-infrared spectra. Recently, we showed that blue light (470 nm) can significantly influence biological systems such as nitric oxide (NO) metabolism and is able to release NO from nitrosyl-hemoglobin or mitochondrial protein complexes. Therefore, the aim of this study was to evaluate and compare the therapeutic value of blue or red light emitting diodes (LEDs) on wound healing in an ischemia disturbed rodent flap model. STUDY DESIGN/MATERIALS AND METHODS: An abdominal flap was rendered ischemic by ligation of one epigastric bundle and subjected to LED illumination with a wavelength of 470 nm (blue, n = 8) or 629 nm (red, n = 8) each at 50 mW/cm(2) and compared to a non-treated control group (n = 8). Illumination was performed for 10 minutes on five consecutive days. RESULTS: LED therapy with both wavelengths significantly increased angiogenesis in the sub-epidermal layer and intramuscularly (panniculus carnosus muscle) which was associated with significantly improved tissue perfusion 7 days after the ischemic insult. Accordingly, tissue necrosis was significantly reduced and shrinkage significantly less pronounced in the LED-treated groups of both wavelengths. CONCLUSIONS: LED treatment of ischemia challenged tissue improved early wound healing by enhancing angiogenesis irrespective of the wavelength thus delineating this noninvasive means as a potential, cost effective tool in complicated wounds.

Low-level laser therapy during postnatal development modulates degeneration and enhances regeneration processes in the hindlimb muscles of dystrophic mice.

OBJECTIVE: The aim of the present study was to determine whether low-level laser therapy (LLLT) at early stages postpartum could affect regeneration and degenerative processes in skeletal muscles of the dystrophic mdx mouse. BACKGROUND DATA: LLLT has been found to modulate various biological processes. It was previously shown that LLLT can markedly promote the process of skeletal muscle regeneration and angiogenesis, as well as reduce apoptosis in skeletal muscle fibers in culture. METHODS AND RESULTS: Eight newborn mdx mice were used. Ga-Al-As diode laser (810 nm) was applied at a power density of10 mW/cm(2) to the surface (area of 0.0255 cm(2)) of hindlimb muscle for 120 sec (fluence of 1.2 J/cm(2)) once a week for 4 consecutive weeks, commencing 1 week post-birth. The contralateral leg served as an untreated (sham) control. Mice were euthanized 2 days following the last laser application, and the muscles were processed for histology. Histological sections were scored for degenerative muscle foci. Statistical analysis revealed a score of 2.91±0.17 in the control, untreated group, which was significantly higher (p<0.001) than the value in the laser-treated group (1.56±0.49), indicating less degenerative foci in the laser-treated muscles. Histology also indicated regeneration (numerous myotubes) in the laser-treated mice, and no regeneration in the non-laser-treated mice. CONCLUSIONS: The results indicate that LLLT applied to mdx mice during postnatal development may have a significant beneficial effect in the induction of regenerative capacity and reduction of degenerative muscle foci in these mice, with possible direct clinical relevance.

The effect of low-level laser therapy on the healing of hard palate mucosa and the oxidative stress status of rats.

OBJECTIVE: The biostimulation effects of low-level laser therapy (LLLT) have been demonstrated recently. This study investigated the effects of LLLT on palatal mucoperiosteal wound healing and oxidative stress status in rats. MATERIAL AND METHOD: Forty-two male Wistar rats weighing 250-300 g were used in this study. A standardized full-thickness wound was created in the mucoperiosteum of the hard palates of the rats using a 3-mm-diameter biopsy punch. Treatment using a GaAlAs laser at a wavelength of 940 nm and a dose of 10 J/cm(2) was initiated after surgery and repeated on the 2nd, 4th, and 6th days post-surgery. Seven animals from each group were sacrificed on the 7th, 14th, and 21st days after surgery. Total antioxidant status and total oxidative status were measured in serum. RESULTS: The histopathological findings revealed reduced numbers of inflammatory cells on the 7th day, increased mitotic activity of fibroblasts on the 14th and 21st day, and the same degree of collagen synthesis and vascularization on the days 7, 14, and 21 in the LLLT group compared with the control group. No significant differences in total oxidative status and total antioxidant status were observed between the groups. CONCLUSION: LLLT using a GaAlAs laser at a wavelength of 940 nm and a dose of 10 J/cm(2) elicited a positive healing effect on palatal mucoperiosteal wounds likely via the induction of fibroblasts. The oxidative stress status was not affected by LLLT.

Effect of low-level laser therapy (λ660 nm) on angiogenesis in wound healing: a immunohistochemical study in a rodent model.

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-ß 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-ß expression (p>0.05). It was concluded that laser treatment (λ660 nm) contributed to increase angiogenesis.

Phototherapy with low-level laser influences the proliferation of endothelial cells and vascular endothelial growth factor and transforming growth factor-beta secretion.

The healing process and the angiogenesis associated with it, is a very important but currently poorly understood area. Low level laser therapy (LLLT) has been reported to modulate the process of tissue repair by stimulation of cellular reaction such as migration, proliferation, apoptosis and cellular differentiation. The aim of this work was to evaluate the influence of laser radiation in the range of visible and infrared light on the proliferation of vascular endothelial cells in vitro and the secretion of angiogenic factors: vascular endothelial growth factor (VEGF)-A and transforming growth factor (TGF)-ß. Vascular human endothelial cells (Ecs) were exposed to radiation with laser beam of the wavelengths: 635 nm (1.875 mW/cm²) and 830 nm (3.75 mW/cm²). Depending on the radiation energy density, the experiment was conducted in four groups : I) the control group (no radiation, 0 J/cm²); II) 635 nm - the energy density was 2 J/cm²; III) 635 nm - 4 J/cm²; IV635 nm - 8 J/cm², II) 830 nm - the energy density was 2 J/cm²; III) 830 nm - 4 J/cm²; IV) 830 nm - 8 J/cm². The proliferation and concentration of VEGF-A and TGF-ß were examined. LLLT with wavelength 635 nm increases endothelial cell proliferation. Significant increase in endothelial cell proliferation and corresponding decrease in VEGF concentration may suggest the role for VEGF in this process. The wavelength of 830 nm was associated with a decrease in TGF-ß secretion.

Evaluation of two protocols for low-level laser application in patients submitted to orthodontic treatment.

INTRODUCTION: Different low-level laser (LLL) irradiation protocols have been tested to accelerate orthodontic tooth movement (OTM). Nevertheless, divergent results have been obtained. It was suggested that the stimulatory action of low level laser irradiation occurs during the proliferation and differentiation stages of bone cellular precursors, but not during later stages. OBJECTIVE: The purpose of this study was to determine the effect of two protocols of LLL irradiation on experimental tooth movement: One with daily irradiations and another with irradiations during the early stages. METHODS: Thirty-six rats were divided into control groups (CG1, CG2, CG3) and irradiated groups (IrG1, IrG2, IrG3) according to the presence of: experimental tooth movement, laser irradiation, type of laser irradiation protocol and date of euthanasia (3th or 8th day of experiment). At the end of experimental periods, a quantitative evaluation of the amount of OTM was made and the reactions of the periodontium were analyzed by describing cellular and tissue reactions and by counting blood vessels. RESULTS: The amount of OTM revealed no significant differences between groups in the same experimental period (p < 0.05). Qualitative analysis revealed the strongest resorption activity in irradiated groups after seven days, especially when using the daily irradiation protocol. There was a higher number of blood vessels in irradiated animals than in animals without orthodontic devices and without laser irradiation (p < 0.05). CONCLUSION: Moreover, angiogenesis was verified in some of the irradiated groups. The irradiation protocols tested were not able to accelerate OTM and root resorption was observed while they were applied.