Superpulsed (Ga-As, 904 nm) low-level laser therapy (LLLT) attenuates inflammatory response and enhances healing of burn wounds

Low-level laser therapy (LLLT) using superpulsed near-infrared light can penetrate deeper in the injured tissue and could allow non-pharmacological treatment for chronic wound healing. This study investigated the effects of superpulsed laser (Ga-As 904 nm, 200 ns pulse width; 100 Hz; 0.7 mW mean output power; 0.4 mW/cm(2) average irradiance; 0.2 J/cm(2) total fluence) on the healing of burn wounds in rats, and further explored the probable associated mechanisms of action. Irradiated group exhibited enhanced DNA, total protein, hydroxyproline and hexosamine contents compared to the control and silver sulfadiazine (reference care) treated groups. LLLT exhibited decreased TNF-α level and NF-kB, and up-regulated protein levels of VEGF, FGFR-1, HSP-60, HSP-90, HIF-1α and matrix metalloproteinases-2 and 9 compared to the controls. In conclusion, LLLT using superpulsed 904 nm laser reduced the inflammatory response and was able to enhance cellular proliferation, collagen deposition and wound contraction in the repair process of burn wounds. Photomicrographs showing no, absence inflammation and faster wound contraction in LLLT superpulsed (904 nm) laser treated burn wounds as compared to the non-irradiated control and silver sulfadiazine (SSD) ointment (reference care) treated wounds.

Phototherapy improves healing of chronic venous ulcers

OBJECTIVE

We tested the hypothesis that LED phototherapy with combined 660-nm and 890-nm light will promote healing of venous ulcers that failed to respond to other forms of treatment.

BACKGROUND DATA

A variety of dressings, growth factors, and adjunct therapies are used to treat venous ulcers, but none seems to yield satisfactory results.

MATERIALS AND METHODS

We used a randomized placebo-controlled double-blind study to compare a total of 20 patients divided with 32 chronic ulcers into three groups. In group 1 the ulcers were cleaned, dressed with 1% silver sulfadiazine (SDZ) cream, and treated with placebo phototherapy (<.03 J/cm(-3)) using a Dynatron Solaris 705 phototherapy research device. In group 2 the ulcers were treated similarly but received real phototherapy (3 J/cm(-2)) instead of placebo. In group 3 (controls), the ulcers were simply cleaned and dressed with SDZ without phototherapy. The ulcers were evaluated with digital photography and computer image analysis over 90 d or until full healing was attained.

RESULTS

Ulcers treated with phototherapy healed significantly faster than controls when compared at day 30 (p +/- 0.01), day 60 (p +/- 0.05), and day 90 (p +/- 0.001), and similarly healed faster than the placebo-treated ulcers at days 30 and 90 (p +/- 0.01), but not at day 60. The beneficial effect of phototherapy was more pronounced when the confounding effect of small-sized ulcers was removed from the analysis. Medium- and large-sized ulcers healed significantly faster with treatment (>or=40% rate of healing per month) than placebo or control ulcers (p +/- 0.05).

CONCLUSION

Phototherapy promotes healing of chronic venous ulcers, particularly large recalcitrant ulcers that do not respond to conventional treatment.

Different photoresponses of Staphylococcus aureus and Pseudomonas aeruginosa to 514, 532, and 633 nm low level lasers in vitro

Low Level Light irradiation (LLLI) may proliferate cell growth at certain conditions during a set of photochemical reactions called biostimulation. However, phototoxic inhibitory reactions after irradiating natural or artificially inoculated cells are possible. The purpose of this study was to determine these effects on Pseudomonas aeruginosa and Staphylococcus aureus. Ar ion laser at 514 nm was used to determine the effect of various energy densities of green light on these bacteria. The most effective energy densities of Ar ion laser were chosen to irradiate both bacteria with He-Ne (633 nm) and SHG Nd:YAG (532 nm) lasers to compare the effect of red and green lights on the growth. Irradiation of Pseudomonas aeruginosa for both He-Ne and SHG Nd:YAG lasers in the presence of toluidine blue O or safranine O as photosensitizers was also studied. All energy densities of Ar ion laser showed a proliferative effect on Pseudomonas aeruginosa and inhibitory effect on Staphylococcus aureus. Similarly, SHG Nd:YAG and He-Ne lasers with chosen energy densities were again proliferating for Pseudomonas aeruginosa and inhibitory for Staphylococcus aureus and SHG Nd:YAG was more effective than He-Ne in both cases. Irradiation of Pseudomonas aeruginosa in the presence of both photosensitizers led to the decrease of the cell population compared to the control.

The efficacy of low-power lasers in tissue repair and pain control: a meta-analysis study

OBJECTIVE

We used statistical meta-analysis to determine the overall treatment effects of laser phototherapy on tissue repair and pain relief.

BACKGROUND DATA

Low-power laser devices were first used as a form of therapy more than 30 years ago. However, their efficacy in reducing pain or promoting tissue repair remains questionable.

METHODS

Following a literature search, studies meeting our inclusion criteria were identified and coded. Then, the effect size of laser treatment, that is, Cohen's d, was calculated from each study using standard meta-analysis procedures.

RESULTS

Thirty-four peer-reviewed papers on tissue repair met our inclusion criteria and were used to calculate 46 treatment effect sizes. Nine peer-reviewed papers on pain control met the inclusion criteria and were used to calculate nine effect sizes. Meta-analysis revealed a positive effect of laser phototherapy on tissue repair (d = +1.81; n = 46) and pain control (d = +1.11; n = 9). The positive effect of treatment on specific indices of tissue repair was evident in the treatment effect sizes determined as follows: collagen formation (d = +2.78), rate of healing (d = +1.57), tensile strength (d = +2.13), time needed for wound closure (d = +0.76), tensile stress (d = +2.65), number and rate of degranulation of mast cells (d = +1.87), and flap survival (d = +1.95). Further, analysis revealed the positive effects of various wavelengths of laser light on tissue repair, with 632.8 nm having the highest treatment effect (d = +2.44) and 780 nm the least (d = 0.60). The overall treatment effect for pain control was positive as well (d = +1.11). The fail-safe number-that is, the number of studies in which laser phototherapy has negative or no effect-needed to nullify the overall outcome of this analysis was 370 for tissue repair and 41 for pain control.

CONCLUSIONS

These findings mandate the conclusion that laser phototherapy is a highly effective therapeutic armamentarium for tissue repair and pain relief.

The efficacy of laser therapy in wound repair: a meta-analysis of the literature

OBJECTIVE

We determined the overall effects of laser therapy on tissue healing by aggregating the literature and subjecting studies meeting the inclusion and exclusion criteria to statistical meta-analysis.

BACKGROUND DATA

Low-level laser therapy (LLLT) devices have been in use since the mid sixties, but their therapeutic value remains doubtful, as the literature seems replete with conflicting findings.

MATERIALS AND METHODS

Pertinent original research papers were gathered from library sources, online databases and secondary sources. The papers were screened and coded; those meeting every inclusion and exclusion criterion were subjected to meta-analysis, using Cohen's d. statistic to determine the treatment effect size of each study.

RESULTS

Twenty-four studies with 31 effect sizes met the stringent inclusion and exclusion criteria. The overall mean effect of laser therapy on wound healing was highly significant (d = +2.22). Sub-analyses of the data revealed significant positive effects on wound healing in animal experiments (d = +1.97) as well as human clinical studies (d = +0.54). The analysis further revealed significant positive effects on specific indices of healing, for example, acceleration of inflammation (d = +4.45); augmentation of collagen synthesis (d = +1.80); increased tensile strength (d = +2.37), reduced healing time (d = +3.24); and diminution of wound size (d = +0.55). The Fail-Safe number associated with the overall effect of laser therapy was 509; a high number representing the number of additional studies-in which laser therapy has negative or no effect on wound healing-required to negate the overall large effect size of +2.22. The corresponding Fail-Safe number for clinical studies was 22.

CONCLUSION

We conclude that laser therapy is an effective tool for promoting wound repair.

Effects of 630-, 660-, 810-, and 905-nm laser irradiation delivering radiant exposure of 1-50 J/cm2 on three species of bacteria in vitro

OBJECTIVE

To examine the effects of low-intensity laser therapy (LILT) on bacterial growth in vitro.

BACKGROUND DATA

LILT is undergoing investigation as a treatment for accelerating healing of open wounds. The potential of coincident effects on wound bacteria has received little attention. Increased bacterial proliferation could further delay recovery; conversely inhibition could be beneficial.

MATERIALS AND METHODS

Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus were plated on agar and then irradiated with wavelengths of 630, 660, 810, and 905 nm (0.015 W/cm(2)) and radiant exposures of 1-50 J/cm(2). In addition, E. coli was irradiated with 810 nm at an irradiance of 0.03 W/cm(2) (1-50 J/cm(2)). Cells were counted after 20 h of incubation post LILT. Repeated measures ANOVA and Tukey adjusted post hoc tests were used for analysis.

RESULTS

There were interactions between wavelength and species (p = 0.0001) and between wavelength and radiant exposure (p = 0.007) in the overall effects on bacterial growth; therefore, individual wavelengths were analyzed. Over all types of bacteria, there were overall growth effects using 810- and 630-nm lasers, with species differences at 630 nm. Effects occurred at low radiant exposures (1-20 J/cm(2)). Overall effects were marginal using 660 nm and negative at 905 nm. Inhibition of P. aeruginosa followed irradiation using 810 nm at 5 J/cm(2) (-23%; p = 0.02). Irradiation using 630 nm at 1 J/cm(2) inhibited P. aeruginosa and E. coli (-27%). Irradiation using 810 nm (0.015 W/cm(2)) increased E. coli growth, but with increased irradiance (0.03 W/cm(2)) the growth was significant (p = 0.04), reaching 30% at 20 J/cm(2) (p = 0.01). S. aureus growth increased 27% following 905-nm irradiation at 50 J/cm(2).

CONCLUSION

LILT applied to wounds, delivering commonly used wavelengths and radiant exposures in the range of 1-20 J/cm(2), could produce changes in bacterial growth of considerable importance for wound healing. A wavelength of 630 nm appeared to be most commonly associated with bacterial inhibition. The findings of this study might be useful as a basis for selecting LILT for infected wounds.

Effect of low intensity monochromatic light therapy (890 nm) on a radiation-impaired, wound-healing model in murine skin

BACKGROUND AND OBJECTIVE

The use of low intensity laser and monochromatic light diodes as a therapeutic modality has become popular in a variety of clinical applications, including the promotion of wound repair. Despite this, the clinical evidence base for such application remains sparse; in contrast, recent studies have demonstrated a number of quantifiable photobiological effects associated with such therapy. In the present study, the effect of low intensity monochromatic light irradiation (MLI) at various radiant exposures upon a radiation-impaired wound model in murine skin was investigated.

STUDY DESIGN/MATERIALS AND METHODS

Male Balb/c mice (n = 50; age matched at 10 weeks) were randomly allocated to five experimental groups (n = 10 each group). In Group 1, mice were left untreated; in Groups 2-5, a well-defined area on the dorsum was exposed to 20 Gy X-ray irradiation. At 72 hours postirradiation, all mice were anaesthetised and a 7-mm-square area wound was made on the dorsum. All wounds were videotaped alongside a marker scale until closure was complete. In Groups 3-5, mice were treated with MLI (0.18, 0.54, and 1.45 J/cm2, respectively) three times weekly using a GaAlAs 890 nm multidiode (n = 60) array unit (270 Hz; maximum rated output, 300 mW; Anodyne, Denver, CO). Subsequently, the area of each wound was measured from video using an image analysis system (Fenestra 2.1), and results were analysed using repeated measure and one-factor ANOVA statistical tests.

RESULTS

X-ray irradiation caused a significant delay (P = 0.0122) in healing by day 7. MLI at 0.18 J/cm2 and 0.54 J/cm2 had no effect upon the rate of wound closure. However, a highly significant (P = 0.0001) inhibition occurred following MLI irradiation at 1.45 J/cm2 by day 16.

CONCLUSION

These findings provide little evidence of the putative stimulatory effects of monochromatic light irradiation in vivo, but, rather, reveal the potential for an inhibitory effect at higher radiant exposures.

Effect of low-intensity laser irradiation (660 nm) on a radiation-impaired wound-healing model in murine skin

BACKGROUND AND OBJECTIVE

The use of low-intensity laser therapy (LILT) as a therapeutic modality has become popular in a variety of clinical applications including the promotion of wound repair. Although the clinical evidence base for such application remains sparse, recent studies have demonstrated a number of quantifiable photobiological effects associated with such therapy. In the present study, the effect of laser irradiation at various radiant exposures on a radiation-impaired wound-healing model in murine skin was investigated.

STUDY DESIGN/MATERIALS AND METHODS

The study included two phases; in phase one, male Balb/c mice (n = 36; age-matched at 10 weeks) were randomly allocated to three experimental groups (n = 12, each group). In all groups, a well-defined area on the dorsum was exposed to 20 Gy x-rays. Seventy-two hours postirradiation, all mice were anaesthetised and a 7 x 7 mm area wound was made on the dorsum. All wounds were videotaped alongside a marker scale (three times weekly) until closure was complete. In groups 2 and 3, mice were treated with laser irradiation (0.5 and 1.5 J/cm(2), respectively) three times weekly by using a 660-nm GaAlAs laser unit (5 kHz; 15 mW; Omega Laser Systems, London, UK). Wound areas were then calculated by using an image analysis system (Fenestra 2.1), and results were analyzed by using repeated measures and one-factor analysis of variance statistical tests. In phase two, two experimental groups were included (n = 12 each group); the protocol was identical to that described for phase 1; however, mice in group 2 were treated with a radiant exposure of 4 J/cm(2).

RESULTS

Results from this investigation demonstrated that treatment with 0.5, 1.5. and 4 J/cm(2) had no beneficial effect on the rate of wound closure (P > 0.05).

CONCLUSION

These findings provide little evidence of the putative stimulatory effects of LILT in vivo at the parameters investigated.

The effect of low level laser therapy (LLLT) on wound healing in horses

Laser therapy is used in many countries, including South Africa, for the treatment of skin wounds. Low level galium aluminium arsenide (GaAlAs) laser was administered to full thickness skin wounds (3 x 3 cm) induced surgically on the dorsal aspect of the metacarpophalangeal joints of 6 crossbred horses in a randomised, blind, controlled study. Treated wounds that received a daily laser dosage of 2 J/cm2 were compared with nontreated control wounds on the opposite leg. There were no wound complications. Both groups of wounds were cleaned daily using tap water. Wound contraction and epithelialisation were evaluated using photoplanimetry. There were no significant differences in wound contraction or epithelialisation between the laser treated and the control wounds. It was therefore concluded that laser therapy had no clinically significant effect on second intention wound healing in this study.