Stimulatory effect of 660 nm low level laser energy on hypertrophic scar-derived fibroblasts: possible mechanisms for increase in cell counts

The additive effects of photobiomodulation and bioactive glasses on enhancing early angiogenesis

Early angiogenesis is important to facilitate biomaterials' osteogenic effects and avoid the bone regeneration failure for large-sized bone defects. Bioactive glasses (BG) have been widely utilized as a biomaterial for bone repair. However, the early angiogenesis of BG may be inadequate. In this study, we explored the effects of photobiomodulation (PBM) combined with BG on early angiogenesis to solve this bottleneck problem of insufficient early angiogenesis. In vitro, human umbilical vein endothelial cells (HUVECs) were cultured with BG extracts and treated with PBM using 1 J/cm2. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) and tubule formation assay were utilized to detect HUVECs' proliferation, vascular growth factor genes expression and tubules formation. In vivo, bone defects at the femoral metaphysis in Sprague-Dawley rats were treated with BG particulates and PBM at 120 J/cm2. Immunohistochemical staining was applied to observe the vascular-like structure formation. In vitro results showed that PBM combined with BG significantly promoted HUVECs' proliferation, genes expression and mature tubules formation. On days 2, 4 and 7, the VEGF gene expression in BG+PBM group was 2.70-, 2.59- and 3.05-fold higher than control (P<0.05), and higher than PBM and BG groups (P<0.05). On days 4 and 7, the bFGF gene expression in BG+PBM group was 2.42- and 1.82-fold higher than control (P<0.05), and also higher than PBM and BG groups (P<0.05). Tube formation assay showed that mature tubules formed in BG+PBM and PBM groups after 4 hours. The tubules number in BG+PBM group was significantly higher than other groups (P<0.05). In vivo results further confirmed that PBM induced early angiogenesis. More vascular-like structures were observed in BG+PBM and PBM groups 2-week post surgery. In conclusion, with the optimum PBM fluence and BG concentration, PBM combined with BG exerted additive effects on enhancing early angiogenesis.

Photobiomodulation Therapy to Mitigate Radiation Fibrosis Syndrome

Objective: We evaluated the role of photobiomodulation (PBM) in radiation fibrosis syndrome (RFS). Background: Radiation therapy (RT) is an important treatment utilized in over half of newly diagnosed cancers. Despite its benefits, patients treated with RT may experience acute and chronic significant side effects depending on both treatment- and patient-related factors. RFS is an important long-term side effect of RT, which can adversely impact patient's quality of life and organ function. With improved oncologic outcomes and survival for cancer patients after radiation, there is an unmet need to address long-term side effects of RT, particularly RFS. Results: Photobiomodulation (PBM) using low energy, nonionizing light primarily in the visible (especially red) or near-infrared spectrum has been demonstrated to decrease acute side effects of radiation in rigorously conducted phase III randomized studies; however, its potential benefit in ameliorating chronic radiation side effects, particularly RFS remains to be investigated. Conclusions: This review summarizes the in vitro data, preclinical animal studies and clinical reports, which showcase the potential benefits of PBM treatments in preventing and reversing RFS.

Combined Non-Ablative Laser and Microfat Grafting for Burn Scar Treatment

BACKGROUND

Burn scar treatment persists as an unsolved problem, involving thousands of affected patients disfigured for life.

OBJECTIVES

We sought to present our experience with the use of combined treatments for patients with burn scars.

METHODS

This was a case series report of the senior author's experience during 8 years utilizing the combined treatments of Fraxel Restore (fractional laser) and microfat graft injection for 288 patients with burn scars.

RESULTS

Laser treatment reduced scar intensity and attenuated skin irregularities and hyperpigmentation. All patients demonstrated marked improvement of skin texture and an increase in scar softness after 3 sessions of microfat grafting. However, the degree of improvement varied between patients and was related to the severity of the scar and the type of tissue. Overall, a 40% to 80% improvement was noted in our patients. All patients and their families expressed satisfaction with the results.

CONCLUSIONS

The combined treatment of Fraxel and microfat grafting is an effective technique for improving the appearance of a hypertrophic scar or keloid on burn patients. Fat tissue stem cells may have helped to repair the damaged skin.

LEVEL OF EVIDENCE: 4

Does blue light restore human epidermal barrier function via activation of Opsin during cutaneous wound healing?

BACKGROUND AND OBJECTIVE

Visible light has beneficial effects on cutaneous wound healing, but the role of potential photoreceptors in human skin is unknown. In addition, inconsistency in the parameters of blue and red light-based therapies for skin conditions makes interpretation difficult. Red light can activate cytochrome c oxidase and has been proposed as a wound healing therapy. UV-blue light can activate Opsin 1-SW, Opsin 2, Opsin 3, Opsin 4, and Opsin 5 receptors, triggering biological responses, but their role in human skin physiology is unclear.

MATERIALS AND METHODS

Localization of Opsins was analyzed in situ in human skin derived from face and abdomen by immunohistochemistry. An ex vivo human skin wound healing model was established and expression of Opsins confirmed by immunohistochemistry. The rate of wound closure was quantitated after irradiation with blue and red light and mRNA was extracted from the regenerating epithelial tongue by laser micro-dissection to detect changes in Opsin 3 (OPN3) expression. Retention of the expression of Opsins in primary cultures of human epidermal keratinocytes and dermal fibroblasts was confirmed by qRT-PCR and immunocytochemistry. Modulation of metabolic activity by visible light was studied. Furthermore, migration in a scratch-wound assay, DNA synthesis and differentiation of epidermal keratinocytes was established following irradiation with blue light. A role for OPN3 in keratinocytes was investigated by gene silencing.

RESULTS

Opsin receptors (OPN1-SW, 3 and 5) were similarly localized in the epidermis of human facial and abdominal skin in situ. Corresponding expression was confirmed in the regenerating epithelial tongue of ex vivo wounds after 2 days in culture, and irradiation with blue light stimulated wound closure, with a corresponding increase in OPN3 expression. Expression of Opsins was retained in primary cultures of epidermal keratinocytes and dermal fibroblasts. Both blue and red light stimulated the metabolic activity of cultured keratinocytes. Low levels of blue light reduced DNA synthesis and stimulated differentiation of keratinocytes. While low levels of blue light did not alter keratinocyte migration in a scratch wound assay, higher levels inhibited migration. Gene silencing of OPN3 in keratinocytes was effective (87% reduction). The rate of DNA synthesis in OPN3 knockdown keratinocytes did not change following irradiation with blue light, however, the level of differentiation was decreased.

CONCLUSIONS

Opsins are expressed in the epidermis and dermis of human skin and in the newly regenerating epidermis following wounding. An increase in OPN3 expression in the epithelial tongue may be a potential mechanism for the stimulation of wound closure by blue light. Since keratinocytes and fibroblasts retain their expression of Opsins in culture, they provide a good model to investigate the mechanism of blue light in wound healing responses. Knockdown of OPN3 led to a reduction in early differentiation of keratinocytes following irradiation with blue light, suggesting OPN3 is required for restoration of the barrier function. Understanding the function and relationship of different photoreceptors and their response to specific light parameters will lead to the development of reliable light-based therapies for cutaneous wound healing. Lasers Surg. Med. © 2018 Wiley Periodicals, Inc.

Low-Level Laser Therapy in Russia: History, Science and Practice

In Russia (formerly USSR) study of biomodulation action (BMA) mechanisms of low-intensity laser irradiation (LILI) began in 1964, immediately after the development of lasers. During the period from 1965 to 1972 several dozens of scientific conferences were held, hundreds of studies were published. Generally, secondary mechanisms and results of LILI effect on patients with various diseases were studied. This data was immediately implemented into practical medicine in the fields of oncology, surgery, dermatology and dentistry, and since 1974 low level laser therapy (LLLT) is included in the standard of state medical care. For 50 years no less than 1000 books were published (monographs, collections, methodical and clinical materials), thousands of researches were carried out. Primary mechanism and patterns of interaction of LILI with acceptors within cells can be represented in the following order: absorption of photon's energy - emergence of a local temperature gradient - release of Ca²⁺ from intracellular stores - stimulating Ca²⁺-dependent processes. Understanding of this process allowed the explanation of all known secondary effects, optimized methods and extremely increased effectiveness of LLLT. Owing to the knowledge of BMA mechanisms of LILI, numerous associated and combined LLLT techniques were developed and are widely used nowadays: locally, on the projection of internal organs, laser acupuncture, reflexology, intracavitary, transdermal and intravenous laser blood illumination, magnetic-laser therapy, laser phoresis, laser-vacuum massage, biomodulation, etc. About 400 000 laser therapeutic devices are used in Russian practical healthcare. Unique, having no analogues in the world devices, are produced - red pulsed laser diodes (wavelength 635 nm, power 5-40 W, pulse duration 100 ns, frequency 10 000 Hz) are designed specially for effective laser therapy.

Photobiomodulation devices for hair regrowth and wound healing: a therapy full of promise but a literature full of confusion

Photobiomodulation is reported to positively influence hair regrowth, wound healing, skin rejuvenation and psoriasis. Despite rapid translation of this science to commercial therapeutic solutions, significant gaps in our understanding of the underlying processes remain. The aim of this review was to seek greater clarity and rationality specifically for the selection of optical parameters for studies on hair regrowth and wound healing. Our investigation of 90 reports published between 1985 and 2015 revealed major inconsistencies in optical parameters selected for clinical applications. Moreover, poorly understood photoreceptors expressed in skin such as cytochrome c oxidase, cryptochromes, opsins etc. may trigger different molecular mechanisms. All this could explain the plethora of reported physiological effects of light. To derive parameters for optimal clinical efficacy of photobiomodulation, we recommend a more rational approach to underpin clinical studies, with research on molecular targets and pathways using well-defined biological model systems to enable translation of optical parameters from in vitro to in vivo. Furthermore, special attention needs to be paid when conducting studies for hair regrowth, aiming for double-blind, placebo-controlled randomized clinical trials as the gold standard for quantifying hair growth.

532 nm Low-Power Laser Irradiation Facilitates the Migration of GABAergic Neural Stem/Progenitor Cells in Mouse Neocortex

BACKGROUND AND OBJECTIVE

Accumulating evidence has shown that low-power laser irradiation (LLI) affects cell proliferation and survival, but little is known about LLI effects on neural stem/progenitor cells (NSPCs). Here we investigate whether transcranial 532 nm LLI affects NSPCs in adult murine neocortex and in neurospheres from embryonic mice.

STUDY DESIGN/MATERIALS AND METHODS

We applied 532 nm LLI (Nd:YVO4, CW, 60 mW) on neocortical surface via cranium in adult mice and on cultured cells from embryonic mouse brains in vitro to investigate the proliferation and migration of NSPCs and Akt expression using immunohistochemical assays and Western blotting techniques.

RESULTS

In vivo experiments demonstrated that 532 nm LLI significantly facilitated the migration of GABAergic NSPCs that were induced to proliferate in layer 1 by mild ischemia. In vitro experiments using GABAergic NSPCs derived from embryonic day 14 ganglionic eminence demonstrated that 532 nm LLI for 60 min promoted the migration of GAD67-immunopositive NSPCs with a significant increase of Akt expression. Meanwhile, the LLI induced proliferation, but not migration, of NSPCs that give rise to excitatory neurons.

CONCLUSION

It is concluded that 532 nm LLI promoted the migration of GABAergic NSPCs into deeper layers of the neocortex in vivo by elevating Akt expression.

Treatment of upper limb lymphedema with low-level laser: a systematic review

Introduction Low-level lasers have been suggested as a complement to lymphedema treatment. However, this therapy’s mechanism of action and its effects are poorly understood up to the present. Objective To conduct a systematic literature review to analyze the effects of low-level laser in the treatment of upper-limb lymphedema in women submitted to breast cancer surgery. Material and methods Randomized clinical trials were included, in Portuguese, English and Spanish, from January 1990 to July 2013. The article search was carried out in the Pubmed, Lilacs and PEDro electronic databases, with the following descriptors:Terapia a Laser de Baixa Intensidade, Linfedema, Câncer de Mama, Low-level laser therapy, Lymphedema, Breast Neoplasms and also through a manual search. Results and discussion Low-level lasers have been used for treating several acute and chronic conditions. However, its application for managing post breast cancer surgery is still recent, often based on empirical evidence. Treating upper-limb lymphedema with low-level laser presented positive results, with reduction in the circumference or volume of the affected limb. Conclusion More studies of high methodological quality are needed in order to better understand the mechanism of action of low-level laser on the lymphatic system and its effects on lymphedema treatement.

Histological and gene expression analysis of the effects of pulsed low-level laser therapy on wound healing of streptozotocin-induced diabetic rats

Diabetes mellitus (DM) is associated with poor wound healing. Studies have shown accelerated wound healing following pulsed low-level laser therapy (LLLT) in non-diabetic animals. The present study aims to evaluate the effect of pulsed LLLT on wound healing in streptozotocin-induced diabetic (STZ-D) rats. We divided 48 rats into two groups of non-diabetic and diabetic. Type 1 DM was induced in the diabetic rat group by injections of STZ. Two, full-thickness skin incisions were made on the dorsal region of each rat. One month after the STZ injection, wounds of the non-diabetic and diabetic rats were submitted to a pulsed, infrared 890-nm laser with an 80-Hz frequency and 0.2 J/cm(2) for each wound point. Control wounds did not receive LLLT. Animals were sacrificed on days 4, 7, and 15 post-injury for histomorphometry and reverse transcription polymerase chain reaction (RT-PCR) analyses of basic fibroblast growth factor (bFGF) gene expression. Pulsed LLLT significantly increased the numbers of macrophages, fibroblasts, and blood vessel sections compared to the corresponding control groups. Semi-quantitative analysis of bFGF gene expression at 48 h post-injury revealed a significant increase in gene expression in both non-diabetic and diabetic rats following LLLT (the ANOVA test). Pulsed LLLT at 0.2 J/cm(2) accelerated the wound healing process in both non-diabetic and diabetic rats as measured by histological characteristics and semi-quantitative bFGF gene expression.

A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase

OBJECTIVE

The purpose of this study was to investigate the safety and efficacy of two novel light sources for large area and full body application, providing polychromatic, non-thermal photobiomodulation (PBM) for improving skin feeling and appearance.

BACKGROUND DATA

For non-thermal photorejuvenation, laser and LED light sources have been demonstrated to be safe and effective. However, lasers and LEDs may offer some disadvantages because of dot-shaped (punctiform) emission characteristics and their narrow spectral bandwidths. Because the action spectra for tissue regeneration and repair consist of more than one wavelength, we investigated if it is favorable to apply a polychromatic spectrum covering a broader spectral region for skin rejuvenation and repair.

MATERIALS AND METHODS

A total of 136 volunteers participated in this prospective, randomized, and controlled study. Of these volunteers, 113 subjects randomly assigned into four treatment groups were treated twice a week with either 611-650 or 570-850 nm polychromatic light (normalized to ∼ 9 J/cm(2) in the range of 611-650 nm) and were compared with controls (n=23). Irradiances and treatment durations varied in all treatment groups. The data collected at baseline and after 30 sessions included blinded evaluations of clinical photography, ultrasonographic collagen density measurements, computerized digital profilometry, and an assessment of patient satisfaction.

RESULTS

The treated subjects experienced significantly improved skin complexion and skin feeling, profilometrically assessed skin roughness, and ultrasonographically measured collagen density. The blinded clinical evaluation of photographs confirmed significant improvement in the intervention groups compared with the control.

CONCLUSIONS

Broadband polychromatic PBM showed no advantage over the red-light-only spectrum. However, both novel light sources that have not been previously used for PBM have demonstrated efficacy and safety for skin rejuvenation and intradermal collagen increase when compared with controls.

The effect of laser diode irradiation on wound healing of rat skin

BACKGROUND

Light amplification by stimulated emission of radiation (LASER) diode irradiation (LDI) has some beneficial effects on the wound healing. However, little is known about the biochemical effect of LDI on wound healing. We have performed animal study to clarify the effect of LDI on wound healing based on microscopic findings.

METHODS

Eight-month-old male rats (NTacSam:SD, SamtakoBioKorea), weighting 250-300 g, were used. Round blade, of 1 cm diameter, was penetrated through the skin and subcutaneous level after elevating the skin just above the thoracic spine of the rats. Laser diode of 655, 785, and 850 nm wavelengths were irradiated to the skin wound for 9 days, 20 min a day. Eight rats were used in each four groups including non-irradiated group. Immunochemical staining was carried out to evaluate pan-cytokeratin and actin, and Masson's trichrome staining was carried to evaluate the cellular and protein components relating to wound healing. Wound size was measured on 9th postoperative day with computer system.

RESULT

Collagen formation was graded as 2+, 3+, and 4 + in the order of non-radiation group, 655, 785, and 850 nm irradiation groups, respectively. Myofibroblast was formed more abundantly in LDI group than in non-irradiated group. The mean values of proliferating cell nuclear antigen (PCNA) were 67.8 ± 5.0, 84.0 ± 4.6, 78.0 ± 6.8, and 74.2 ± 4.0 nm in the order of non-radiation group, 655, 785, and 850 nm irradiation groups, respectively. Mean values of defect size were 2,840 ± 124 um, 1,689 ± 125 um, 1,254 ± 94 um, and 1,423 ± 113 in the order of non-radiation group, 65, 785, and 850 nm groups, respectively.

CONCLUSION

LDI has beneficial effects on the formation of fibroblast and collagen, and results in better wound healing.

In vitro Comparison of Light-Emitting Diodes and Carnosic Acid Effects on Keratinocyte Proliferation and Wound Healing

Introduction:

Light-emitting diode (LED) therapy uses different wavelengths of light and has been reported to accelerate cutaneous wound healing. Carnosic acid is an antioxidant that is also thought to be photoprotective. We designed an in vitro study to examine the effects of LED and carnosic acid on the proliferation and migration of human keratinocytes.

Materials and Methods:

Clinically normal human keratinocytes were cultured and exposed to two wavelengths: 620 nm and 660 nm LED at different fluences. In the second part of this study, a different batch of human keratinocytes was grown in culture, and different concentrations of carnosic acid were added.

Results:

At the two wavelengths that were used, LED did not appear to have any therapeutic effect and was not effective in stimulating keratinocyte proliferation. Exposure to greater energy levels (increased fluence) produced increased cell damage that was directly proportional to the increase in energy. On the other hand, treatment of the cell cultures with the antioxidant carnosic acid resulted in an increase of keratinocyte cell proliferation, and this increase was also proportional to the concentration of carnosic acid.

Conclusions:

This study did not support the hypothesis that LED treatment results in keratinocyte proliferation; however, carnosic acid, a potent antioxidant, stimulated keratinocyte production and could be implicated in wound healing and rejuvenation.

The nuts and bolts of low-level laser (light) therapy

Soon after the discovery of lasers in the 1960s it was realized that laser therapy had the potential to improve wound healing and reduce pain, inflammation and swelling. In recent years the field sometimes known as photobiomodulation has broadened to include light-emitting diodes and other light sources, and the range of wavelengths used now includes many in the red and near infrared. The term "low level laser therapy" or LLLT has become widely recognized and implies the existence of the biphasic dose response or the Arndt-Schulz curve. This review will cover the mechanisms of action of LLLT at a cellular and at a tissular level and will summarize the various light sources and principles of dosimetry that are employed in clinical practice. The range of diseases, injuries, and conditions that can be benefited by LLLT will be summarized with an emphasis on those that have reported randomized controlled clinical trials. Serious life-threatening diseases such as stroke, heart attack, spinal cord injury, and traumatic brain injury may soon be amenable to LLLT therapy.

The nuts and bolts of low-level laser (light) therapy

Soon after the discovery of lasers in the 1960s it was realized that laser therapy had the potential to improve wound healing and reduce pain, inflammation and swelling. In recent years the field sometimes known as photobiomodulation has broadened to include light-emitting diodes and other light sources, and the range of wavelengths used now includes many in the red and near infrared. The term "low level laser therapy" or LLLT has become widely recognized and implies the existence of the biphasic dose response or the Arndt-Schulz curve. This review will cover the mechanisms of action of LLLT at a cellular and at a tissular level and will summarize the various light sources and principles of dosimetry that are employed in clinical practice. The range of diseases, injuries, and conditions that can be benefited by LLLT will be summarized with an emphasis on those that have reported randomized controlled clinical trials. Serious life-threatening diseases such as stroke, heart attack, spinal cord injury, and traumatic brain injury may soon be amenable to LLLT therapy.

In vitro effect of 470 nm LED (Light Emitting Diode) in keloid fibroblasts

PURPOSE

To quantify keloid fibroblasts after irradiation with 470nm blue LED, in vitro.

METHODS

Fibroblasts from keloid and adjacent skin have been obtained from 6 patients. Cells have been cultivated and maintained in DMEM culture medium. In Petri dishes, they were irradiated with energy doses of 6J, 12J and 18J. After 24 h, counting was done by the average of the triplicates for each sample.

RESULTS

There were no significant differences in the number of irradiated keloid fibroblasts at the studied doses (p=0.261). In adjacent skin fibroblasts, differences were observed (p=0.025) concerning the doses of 18 J and 6 J (p=0.03).

CONCLUSIONS

There was a reduction in the number of adjacent skin fibroblasts irradiated with 470nm blue LED at the energy dose of 18 J compared to the ones irradiated at the energy dose of 6 J. There were no changes in keloid fibroblasts counting at any of the doses applied, 24 h after irradiation.

Use of laser phototherapy on a delayed wound healing of oral mucosa previously submitted to radiotherapy: case report

Radiotherapy produces both acute and delayed effects on mucosal tissues, disturbing their healing. This report shows a successful treatment with laser phototherapy (LPT) on a delayed wound healing in oral mucosa previously submitted to radiotherapy with a follow up of 3 years. A 47-year-old patient treated 6 months earlier for tongue squamous cell carcinoma by surgery and radiotherapy presented with a mass in the operated area. Biopsy showed chronic inflammatory infiltrate around a residual polyglactin suture. After 2 months there was a painful mucosal dehiscence on the biopsy site. LPT was performed using a semiconductor laser with 660-nm wavelength (InGaAlP) and spot size of 0·04 cm(2) . The parameters applied were 40 mW, 4 Jcm(2) /point, 0·16 J/point, 2·4 J/session. The irradiation was performed punctually, through contact mode in 15 points (4 seconds/point), on top of and around the lesion, during ten sessions. The wound healed completely after ten sessions. This treatment proved to be conservative and effective, inducing healing of a chronic wound in a tissue previously submitted to radiotherapy.

Photodynamic therapy mediated by methylene blue dye in wound healing

OBJECTIVE

We sought to investigate the wound-healing process after photodynamic therapy (PDT) mediated by methylene blue dye (MB).

BACKGROUND DATA

Few scientific studies show the PDT roles in wound healing.

MATERIALS AND METHODS

One hundred rats were given a circular wound on the back, inflicted with a 6-mm-diameter punch. The animals were divided into four groups: control (no treatment); dye (topical application of MB); laser (InGaAlP, 117.85 J/cm(2), 100 mW, 660 nm, single point); and PDT (topical application of MB followed by laser irradiation). After 1, 3, 5, 7, and 14 days, the cutaneous wounds were photographed and assessed with histopathologic examination by using light microscope. Changes seen in edema, necrosis, inflammation, granulation tissue, re-epithelialization, and number of young fibroblasts were semiquantitatively evaluated. The wound-area changes were measured with special software and submitted to statistical analysis.

RESULTS

The laser group demonstrated the smallest wound area at 14 days after the surgical procedure (p < 0.01). Concerning complete re-epithelialization, the laser group showed it at 5-7 days after surgery, whereas the PDT and the other groups showed it at 14 days.

CONCLUSIONS

Laser interaction with tissue is somehow changed when exposed to the MB. PDT mediated by MB was not prejudicial to wound healing, as no delay occurred compared with the control group.

Photo-stimulatory effect of low energy helium-neon laser irradiation on excisional diabetic wound healing dynamics in Wistar rats

BACKGROUND

Generally, the significances of laser photo stimulation are now accepted, but the laser light facilitates wound healing and tissue repair remains poorly understood.

AIMS

We have examined the hypothesis that the laser photo stimulation can enhance the collagen production in diabetic wounds using the excision wound model in the Wistar rat model.

METHODS

The circular wounds were created on the dorsum of the back of the animals. The animals were divided into two groups. The study group (N = 24) wound was treated with 632.8 nm He-Ne laser at a dose of 3-9 J/cm(2) for 5 days a week until the wounds healed completely. The control group was sham irradiated.

RESULT

A significant increase in the hydroxyproline content and reduction in the wound size were observed in the study group. The pro-healing actions seem to be due to increased collagen deposition as well as better alignment and maturation.

CONCLUSION

The biochemical analysis and clinical observation suggested that 3-6 J/cm(2) laser photo stimulation facilitates the tissue repair process by accelerating collagen production in diabetic wound healing.

Quantification of fibrosis and mast cells in the tissue response of endodontic sealer irradiated by low-level laser therapy

Low-level laser therapy (LLLT) accelerates tissue repair. Mast cells induce the proliferation of fibroblasts and the development of local fibrosis. The objective of this study was to quantify fibrosis rate and mast cells in connective tissue after endodontic sealer zinc oxide and eugenol (ZOE) was implanted and submitted to LLLT, immediately after implant and again 24 h later. Sixty mice were distributed into three groups: GI, GII, and GIII (n = 20). In GI, the tubes filled with Endofill were implanted in the animals and were not irradiated with LLLT. In GII, the tubes containing Endofill were implanted in the animals and then irradiated with red LLLT (InGaAIP) 685-nm wavelength, D = 72 J/Cm(2), E = 2 J, T = 58 s, P = 35 mW, and in GIII, the tubes with Endofill were implanted and irradiated with infrared LLLT (AsGaAl) 830-nm wavelength, D = 70 J/Cm(2), E = 2 J, T = 40 s, P = 50 mW. After 7 days and 30 days, the animals were killed. A series of 6-µm-thick sections were obtained and stained with Toluidine Blue and Picrosirius and analyzed under a standard light microscope using a polarized light filter for the quantification of fibrosis. The statistics were qualitative and quantitative with a significance of 5%. The irradiation with LLLT did not offer improvement in the fibrosis rate, however, it provided a significant decrease in the concentration of independent mast cells for the period studied.

In vivo effects on the expression of vascular endothelial growth factor-A165 messenger ribonucleic acid of an infrared diode laser associated or not with a visible red diode laser

OBJECTIVE

This study investigated and correlated the kinetic expression of vascular endothelial growth factor (VEGF)-A(165) messenger ribonucleic acid (mRNA) with the associated use or not of an infrared laser and a visible red laser during the wound healing in rats.

BACKGROUND DATA

There is a lack of scientific evidence demonstrating the influence of low-level laser therapy (LLLT) on the expression of VEGF mRNA in vivo.

MATERIALS AND METHODS

Forty-five Wistar rats were randomly allocated to one of three groups: I (n = 5, nonoperated animals), II (n = 25, operated animals), and III (n = 25, animals operated and subjected to laser irradiation). A surgical wound was performed using a scalpel in the right side of the tongue of operated animals. In group III, two sessions of laser irradiation were performed, one right after the surgical procedure (infrared laser, 780 nm, 70 mW, 35 J/cm(2)) and the other 48 h later (visible red laser, 660 nm, 40 mW, 5 J/cm(2)). Five animals each were sacrificed 1, 3, 5, and 7 days postoperatively in groups II and III, and samples of tongue tissue were obtained. The animals of group I were sacrificed on day 7. Total RNA was extracted using guanidine-isothiocyanate-phenol-chloroform method. The results of horizontal electrophoresis after reverse transcription polymerase chain reaction permitted the ratio of VEGF-A(165) mRNA and glyceraldehyde 3-phosphate dehydrogenase mRNA expression for groups I, II, and III to be assessed (two-way analysis of variance and Tukey test, p < 0.05).

RESULTS

The expression of VEGF-A(165) mRNA in group II (0.770 +/- 0.098) was statistically greater than that observed in groups I (0.523 +/- 0.164) and III (0.504 +/- 0.069) in the first day after surgery (p < 0.05). Significant differences between the groups were not observed in other time periods.

CONCLUSION

LLLT influenced the expression of VEGF-A(165) mRNA during wound healing after a surgical procedure on the tongue of Wistar rats.

Low-level laser therapy using 80-Hz pulsed infrared diode laser accelerates third-degree burn healing in rat

OBJECTIVE

To evaluate 80-Hz pulsed infrared diode low-level laser therapy (LLLT) for third-degree burn healing in rats.

BACKGROUND DATA

Review of the literature indicates that LLLT has a biostimulatory effect on wound healing, although no clear recommendation can be made yet.

METHODS

Forty-eight male rats were divided into groups 1 and 2. On day 0, three third-degree burns were made on the dorsum of each rat using steam. In group 1, the first burn was exposed to an 80-Hz pulsed 890-nm infrared diode laser at 0.396 J/cm2 three times a week. In group 2, the first burn was exposed to the inactivated laser. In both groups, the second burns were treated with topical application of nitrofurazone 0.2%, and third burns did not receive any treatment and were considered as control burns. Burns were clinically examined. The rats were treated for 8, 12, and 20 days in both groups. On days 8, 2, and 20, microbiological samples of burns were collected and analyzed. Data were analyzed using the chi-square method.

RESULTS

The paired Student t-test showed that the wound closure rate of laser-treated burns (17.6+/-1.86 days) was significantly longer than that of the control burns (19.6+/-0.81 days) (p=0.007).The number of laser-treated burns that closed was significantly higher than controls. Chi-square tests showed that there was not significant difference between each microorganism (Staphylococcus epidermis, S. aureus and Pseudomonas aeruginosa).

CONCLUSION

LLLT using an 80-Hz pulsed infrared diode laser accelerated third-degree burn healing in rat.

Effects of near-infrared laser exposure in a cellular model of wound healing

BACKGROUND

Clinical studies have demonstrated beneficial outcomes for low-level laser therapy (LLLT) using near-infrared (NIR) wavelengths. It has been hypothesized that the benefits of NIR LLLT are due in part to the thermal effects of NIR exposure. However, it is not clear whether photochemical interactions between NIR light and superficial tissues contribute to beneficial outcomes. To investigate the photochemical effects of NIR exposure, the efficacy of 980 nm NIR LLLT on human fibroblast growth rates is investigated using an in vitro model of wound healing.

METHODS

A small pipette is used to induce a wound in fibroblast cell cultures, which are imaged at specific time intervals over 48 h and exposed to a range of laser doses (1.5-66 J/cm(2)) selected to encompass the range of doses used during other in vivo and in vitro studies. For each image acquired, wound sizes were quantified using a novel application of existing image processing algorithms.

RESULTS

Cell growth rates were compared across different laser exposure intensities with the same exposure duration, and across different laser exposure durations with the same exposure intensity. Exposure to low- and medium-intensity laser light accelerates cell growth, whereas high-intensity light negated the beneficial effects of laser exposure. Cell growth was accelerated over a wide range of exposure durations using medium-intensity laser light, with no significant inhibition of cell growth at the longest exposure durations used in this study.

CONCLUSION

Low-level exposure to 980 nm laser light can accelerate wound healing in vitro without measurable temperature increases. However, these results also demonstrate the need for appropriate supervision of laser therapy sessions to prevent overexposure to NIR laser light that may inhibit cell growth rates observed in response to lower intensity laser exposure.

The light revival: does phototherapy promote wound healing? A review

BACKGROUND

Throughout history, light has been recognised as a potential source of healing. The introduction of lasers made it possible to modify and control light for optimum therapeutic use.

AIM

This paper reviews recent clinical trials that test phototherapy on human models in order to assess the value of phototherapy in routine wound care.

METHOD

A literature search was undertaken using a variety of sources including online databases.

RESULTS

The results of numerous in vitro and animal investigations suggest that phototherapy may stimulate cell activity and promote tissue repair. Reports of human clinical trials are relatively few. There is inconsistency of selected treatment parameters amongst studies testing the effect of phototherapy on wound healing. Clinical trials using human models do not provide sufficient evidence to establish the usefulness of phototherapy as an effective tool in wound care regimes.

CONCLUSION

Further well designed research trials are required to determine the true value of phototherapy in routine wound care.

Low-level laser irradiation promotes cell proliferation and mRNA expression of type I collagen and decorin in porcine Achilles tendon fibroblasts in vitro

Achilles tendon problems are commonly encountered in sports medicine and low-level laser therapy (LLLT) is widely used in rehabilitative applications to decrease pain, reduce inflammatory processes, and promote tissue healing. This study examined the effects on the proliferation of porcine Achilles tendon fibroblasts and gene expression, using different doses of low-level laser irradiation (LLLI). Four groups of identically cultured fibroblasts were exposed to LLLI and harvested after 24 h. The control group (Group 1) was subjected to no LLLI. Other groups received 1 J/cm2 (Group 2), 2 J/cm2 (Group 3), and 3 J/cm2 (Group 4), respectively. Cell proliferation and mRNA expressions of type I collagen and decorin were then measured. When compared to the control group, the cell proliferation of irradiated Achilles tendon fibroblasts in the other three groups increased significantly by 13% +/- 0.8% (Group 2), 30% +/- 0.4% (Group 3), and 12% +/- 0.6% (Group 4) respectively. But progressively higher laser intensity did not achieve a correspondingly higher cell proliferation effect in Achilles tendon fibroblasts. The mRNA expressions of decorin and type I collagen in fibroblasts with LLLI were significantly higher (p < 0.05). Therefore, suitable dosages of LLLI may result in more effective tissue healing by promoting type I collagen and decorin synthesis. However, these positive effects of LLLI on the repair of the Achilles tendon in humans should be further investigated in clinic.

Low-Level Laser Effect on Mandibular Distraction Osteogenesis

PURPOSE

The purpose of this study was to determine whether low-level laser (LLL) application during distraction osteogenesis could accelerate bone regeneration and decrease the length of the consolidation phase and thereby reduce potential patient morbidity.

MATERIALS AND METHODS

Nine adult female New Zealand white rabbits underwent bilateral mandibular corticotomies and placement of unidirectional distraction devices (KLS-Martin LP, Jacksonville, FL). Each rabbit served as its own internal control. After a latency of 1 day, distraction progressed bilaterally at 1 mm per day for 10 days. Immediately after each device activation, the experimental side, chosen randomly, was treated with real LLL (Laser Medical Systems, Hedehusene, Denmark) of 6.0 J x 6 transmucosal sites in the area of the distraction gap. Radiographs were taken presurgically, immediately postsurgically, and weekly until sacrifice, and the bone was analyzed using a semiquantitative 4-point scale (Bone Healing Score [BHS]). Three animals each were sacrificed at 2, 4, and 6 weeks postdistraction, and each hemimandible was prepared for histologic examination in a blinded fashion.

RESULTS

Ten millimeters of distraction was achieved in each rabbit bilaterally. Radiographically, the BHS was higher for the LLL-treated group at all time periods. Histologically, the area of new bone trabeculation and ossification was more advanced for the LLL-treated group, with less intervening fibrovascular intermediate zone in the bony regenerate, at all time periods. The formation of a complete inferior border occurred sooner in the treatment group than in the controls.

CONCLUSIONS

LLL accelerates the process of bone regeneration during the consolidation phase after distraction osteogenesis. The adjunctive use of LLL may allow a shortened period of consolidation and therefore permit earlier device removal, with the avoidance of morbidity associated with prolonged device retention.

Comparative Study Using 685-nm and 830-nm Lasers in the Tissue Repair of Tenotomized Tendons in the Mouse

OBJECTIVE

The objective of this study was to evaluate the effects of 685- and 830-nm laser irradiations, at different fluences on the healing process of Achilles tendon (Tendon calcaneo) of mice after tenotomy.

BACKGROUND DATA

Some authors have shown that low-level laser therapy (LLLT) is able to accelerate the healing process of tendinuos tissue after an injury, increasing fibroblast cell proliferation and collagen synthesis. However, the mechanism by which LLLT acts on healing process is not fully understood.

METHODS

Forty-eight male mice were divided into six experimental groups: group A, tenomized animals, treated with 685 nm laser, at the dosage of 3 J/cm(2); group B, tenomized animals, treated with 685-nm laser, at the dosage of 10 J/cm(2); group C, tenomized animals, treated with 830-nm laser, at dosage of 3 J/cm(2); group D, tenomized animals, treated with 830-nm laser, at the dosage of 10 J/cm(2); group E, injured control (placebo treatment); and group F, non-injured standard control. Animals were killed on day 13 post-tenotomy, and their tendons were surgically removed for a quantitative analysis using polarization microscopy, with the purpose of measuring collagen fibers organization through the birefringence (optical retardation [OR]).

RESULTS

All treated groups showed higher values of OR when compared to injured control group. The best organization and aggregation of the collagen bundles were shown by the animals of group A (685 nm, 3 J/cm(2)), followed by the animals of group C and B, and finally, the animals of group D.

CONCLUSION

All wavelengths and fluences used in this study were efficient at accelerating the healing process of Achilles tendon post-tenotomy, particularly after the 685-nm laser irradiation, at 3 J/cm(2). It suggests the existence of wavelength tissue specificity and dose dependency. Further studies are required to investigate the physiological mechanisms responsible for the effects of laser on tendinuos repair.

Photoradiation could influence the cytoskeleton organization and inhibit the survival of human hepatoma cells in vitro

Low-power laser therapy has become popular in clinical applications including promoting wound healing and pain relief. However, effects of this photoradiation on human hepatoma cells are rarely studied. Previously, we found 808 nm gallium aluminum arsenide (GaAlAs) continuous wave laser had an inhibitory effect on the proliferation of human hepatoma cell lines HepG2 and J-5 at the energy density of 5.85 and 11.7 J/cm(2), respectively. The aim of the present study was to evaluate the possible mechanism of action of this photoradiation on HepG2 and J-5 cells. HepG2 and J-5 cells were cultured in 24-well plates for 24 h. After photoradiation by 130 mW 808 nm GaAlAs continuous wave laser for different time intervals (0, 30, 60, 90, 120, 150, and 180 s), Western blot and immunofluorescent staining were used to examine the expression and distribution of histone and cytoskeletal proteins. The cell counts as well as histone and synemin expression of HepG2 and J-5 cells were reduced by photoradiation at the energy density of 5.85 and 11.7 J/cm(2), respectively. Furthermore, the architecture of cytoskeletons and the distribution of intermediate filament-associated proteins (plectin and synemin) were disorganized by photoradiation. Photoradiation by 808 nm GaAlAs continuous wave laser at the energy density of 5.85 and 7.8 J/cm(2) inhibited the survival of human hepatoma cell lines. The mechanism might reduce synthesis of histone and synemin. Reduced histone synthesis might further reduce the proliferation rate of these cells. Reduced synemin synthesis might result in the destruction of the cytoskeleton. Therefore, the net effects by this photoradiation were reduced cell survival.

Effect of In-Ga-Al-P diode laser irradiation on angiogenesis in partial ruptures of Achilles tendon in rats

OBJECTIVE

This study was conducted to analyze the effect of different irradiances of low-level laser therapy (LLLT) on angiogenesis after partial rupture of Achilles tendon of rats.

BACKGROUND DATA

METHODS

Ninety-six animals were divided into three groups subject to treatment during 3, 5, and 7 days post-lesion. Thirty-two animals were used in each group. The groups were further divided into four subgroups with eight animals in each, receiving In-Ga-Al-P laser (660 nm) treatment at (1) mean output of 10 mW, (2) 40 mW during 10 sec, (3) a sham subgroup, and (4) a non-treatment subgroup. Each animal was subjected to a lesion of the Achilles tendon by dropping a 186-g weight from a 20-cm height over the tendon. Treatment was initiated 6 h post-injury for all the groups. Blood vessels were colored with India ink injection and were examined in a video microscope.

RESULTS

Laser exposure promoted an increase in blood vessel count when compared to controls. The 40-mW group showed early neovascularization, with the greatest number of microvessels after three laser applications. The 10-mW subgroup showed angiogenesis activity around the same time as the sham laser group did, but the net number of vessels was significantly higher in the former than in the controls. After seven irradiations, the subgroup receiving 40 mW experienced a drop in microvessel number, but it was still higher than in the control groups.

CONCLUSIONS

LLLT of different intensities seems to promote neovascularization in damaged Achilles tendons of rats after partial rupture compared to controls.

Probing the differential effects of infrared light sources IR1072 and IR880 on human lymphocytes: evidence of selective cytoprotection by IR1072

Light therapy, both laser and LED, have been shown to provide clinical benefit in many therapeutic arenas. The effects of IR1072 and IR880 were investigated, using a range of single and multiple irradiation protocols, for their effect on freshly prepared human lymphocytes stimulated with phytohemagglutinin. Viable cell numbers remained significantly higher after irradiation with IR1072 and were significantly lower after IR880 irradiation compared to untreated controls, following a daily single irradiation over a 5-day period. Cell numbers were significantly higher after pre-treatment with IR1072 and exposure to UVA, compared to cells treated with UVA only. Cells irradiated twice on Day 3 post-harvest with various wavebands confirm on Day 5, an increase in % cell viability after IR1072, and IR1072 alternating with IR1268 irradiation, and a decrease in % cell viability after IR880 irradiation alone. Further, wavebands tested displayed no significant differences compared to the control. Cells were collected after exposure on Days 3 and 5 with IR1072 and IR880 treatments and protein levels were compared using quantitative immunoblotting probed with an anti-iNOS antibody. Following IR1072, but not IR880, treatment there was a 4.9+/-2.1-fold higher iNOS protein expression in treated cells compared to the control on Day 5 post-treatment.

Helium-neon laser in viability of random skin flap in rats

BACKGROUND AND OBJECTIVES

The purpose of this study was to determine the role of helium-neon (He-Ne) laser random skin flap viability in rats.

STUDY DESIGN/MATERIALS AND METHODS

Experimentally controlled randomized study. Forty-eight Wistar-EPM rats were used, weighed, and divided into 4 groups with 12 rats each. The random skin flap was performed measuring 10 x 4 cm, with a plastic sheet interposed between the flap and the donor site. The Group 1 (control) underwent sham irradiation with He-Ne laser. The Group 2 was submitted to laser irradiation, using the punctual contact technique on the skin flap surface. The Group 3 was submitted to laser irradiation surrounding the skin flap, and the Group 4 was submitted to laser irradiation both on the skin flap surface and around it. The experimental groups were submitted to He-Ne laser irradiation with 3 J/cm(2) energy density immediately after the surgery and for the four subsequent days. The percentage of necrotic area of the four groups was calculated at the 7th post-operative day, through a paper-template method.

RESULTS

Group 1 reached an average necrotic area of 48.86%; Group 2, 38.67%; Group 3, 35.34%; and Group 4, 22.61%. After the statistic analysis, results showed that all experimental groups reached statistically significant values when compared to the control group, and Group 4 was the best one, when compared to all groups of this study (P<0.001).

CONCLUSION

The He-Ne laser irradiation was efficient to increase random skin flap viability in rats.

Green Light Emitting Diode Irradiation Enhances Fibroblast Growth Impaired by High Glucose Level

BACKGROUND AND OBJECTIVE

The chronic metabolic disorder diabetes mellitus is an important cause of morbidity and mortality due to a series of common secondary metabolic complications, such as the development of severe, often slow healing skin lesions. In view of promoting the wound-healing process in diabetic patients, this preliminary in vitro study investigated the efficacy of green light emitting diode (LED) irradiation on fibroblast proliferation and viability under hyperglycemic circumstances.

MATERIALS AND METHODS

To achieve hyperglycemic circumstances, embryonic chicken fibroblasts were cultured in Hanks' culture medium supplemented with 30 g/L glucose. LED irradiation was performed on 3 consecutive days with a probe emitting green light (570 nm) and a power output of 10 mW. Each treatment lasted 3 min, resulting in a radiation exposure of 0.1 J/cm2.

RESULTS

A Mann-Whitney U test revealed a higher proliferation rate (p = 0.001) in all irradiated cultures in comparison with the controls.

CONCLUSION

According to these results, the effectiveness of green LED irradiation on fibroblasts in hyperglycemic circumstances is established. Future in vivo investigation would be worthwhile to investigate whether there are equivalent positive results in diabetic patients.

Determining optimal dose of laser therapy for attachment and proliferation of human oral fibroblasts cultured on titanium implant material

The purpose of this study was to investigate the influence of single or multiple doses of low-level laser therapy (LLLT) on attachment and proliferation of human gingival fibroblasts in a standardized, reproducible in vitro model. Titanium discs were randomly allotted to one of three groups: group I served as a control, group II was exposed to a single laser dose of 3 J/cm2, and the three subgroups in group III were exposed to laser doses of 0.75, 1.5, and 3 J/cm2. To examine the possible thermal effects of laser exposure on the cell culture, the temperature in the Petri dish was measured for every dose used, before and during irradiation. For attachment assays, groups II and III were exposed to laser irradiation and then seeded onto titanium discs. In group III, the exposures were repeated after 3 and 6 h. Cells were cultured for 6 and 24 h and stained with Hoechst and Propidium. Attached cells were counted under a light microscope. To investigate the effect of LLLT on cell proliferation after 48 h, 72 h, and 7 days, cells were cultured on titanium discs for 24 h and then exposed to laser irradiation for 1 day and 3 consecutive days, respectively. Cell proliferation was determined by counting cells under the microscope and by a cell proliferation enzyme-linked immunosorbent assay system. No increase of temperature of the cell cultures occurred before or during laser exposure at any of the doses tested. Both single and multiple doses of LLLT significantly enhanced cellular attachment (p<0.05). The proliferation assays showed higher cell proliferation (p<0.05) in group III at doses of 1.5 and 3 J/cm2 after 72 h and 7 days, with agreement between staining and enzyme-linked immunosorbent assay. It is concluded that, in this cellular model, the attachment and proliferation of human gingival fibroblasts are enhanced by LLLT in a dose-dependent manner.

Combined treatment of therapeutic laser and herbal application improves the strength of repairing ligament

The present study investigated the effects of combined therapeutic laser and herbal medication protocols on injured medial collateral ligaments (MCLs) of rat knees. Fully 36 rats were evenly divided into 9 groups. Right MCLs of groups 1 to 6 and 8 were transected, while that of groups 7 and 9 remained intact. After surgery, group 1 was treated with 1 session of high-dosed laser; group 2 with 9 sessions of low-dosed laser; group 3 with an herbal plaster; groups 4 and 5 received combined treatments of groups 1 and ss and 2, and 3 respectively; groups 6 and 7 received only bandaging; groups 8 and 9 received placebo laser and no treatment, respectively. All MCLs were subjected to biomechanical testing at 3 weeks postsurgery. Results revealed significant differences among groups in ultimate tensile strength (UTS) and stiffness (p < 0.01). Combination of multiple low-dosed laser treatment with herbal treatment (group 5) resulted in higher UTS than either no treatment (groups 6 and 8), single high-dosed laser treatment (group 1), multiple low-dosed laser treatment (group 2), or herbal treatment (group 2) alone. We concluded that combined applications of laser and herb can enhance further biomechanical properties of repairing rat MCLs than separate applications at 3 weeks postinjury.

Low power laser irradiation alters gene expression of olfactory ensheathing cells in vitro

BACKGROUND AND OBJECTIVES

Both photobiomodulation (PBM) and olfactory ensheathing cells (OECs) transplantation improve recovery following spinal cord injury. However, neither the combination of these two therapies nor the effect of light on OECs has been reported. The purpose of this study was to determine the effect of light on OEC activity in vitro.

MATERIALS AND METHODS

OECs were purified from adult rat olfactory bulbs and exposed to 810 nm light (150 mW; 0, 0.2, or 68 J/cm(2)). After 7-21 days in vitro, cells underwent immunocytochemistry or RNA extraction and RT-PCR.

RESULTS

Analysis of immunolabeling revealed a significant decrease in fibronectin expression in the cultures receiving 68 J/cm(2). Analysis of gene expression revealed a significant (P < 0.05) increase in brain derived neurotrophic factor (BDNF), glial derived neurotrophic factor (GDNF), and collagen expression in the 0.2 J/cm(2) group in comparison to the non-irradiated and 68 J/cm(2) groups. OEC proliferation was also found to significantly increase in both light treated groups in comparison to the control group (P < 0.001).

CONCLUSIONS

These results demonstrate that low and high dosages of PBM alter OEC activity, including upregulation of a number of neurotrophic growth factors and extracellular matrix proteins known to support neurite outgrowth. Therefore, the application of PBM in conjunction with OEC transplantation warrants consideration as a potential combination therapy for spinal cord injury.

A Preliminary Report on the Effect of Laser Therapy on the Healing of Cutaneous Surgical Wounds as a Consequence of an Inversely Proportional Relationship between Wavelength and Intensity: Histological Study in Rats

OBJECTIVE

The objective of the present investigation was to assess the histological effects of different wavelengths and intensities on the healing process of cutaneous wounds.

BACKGROUND DATA

Tissue repair is a dynamic interactive process which involves mediators, cells and extra-cellular matrix. Several reports on the use of laser therapy have shown that the healing process is positively affected when the correct parameters are used.

METHODS

Eighteen standardized wounds were surgically created on the dorsum of male and female Wistar rats, which were subsequently divided into two experimental groups according to wavelength used lambda.670 or lambda685 nm) for lasertherapy (LLLT). Each group was divided into three subgroups of three animals according to the intensity of the applied irradiation (2, 15, or 25 mW). Twelve animals were used as untreated controls and were not irradiated. The irradiation was carried out during seven consecutive days. The animals were sacrificed eight days after surgery. The specimens were removed, kept in 4% formaldehyde for 24 h, routinely prepared to wax, stained with H&E, and analyzed under light microscopy.

RESULTS

For both groups, light microscopy showed a substitution repair process; however, when LLLT was used, a positive biomodulatory effect was detectable, chiefly associated with shorter wavelength and low intensity.

CONCLUSIONS

The results of the present study indicate that LLLT improved cutaneous wound repair and that the effect is a result of an inversely proportional relationship between wavelength and intensity, with treatment more effective when combining higher intensity with short wavelength or lower intensity with higher wavelength.

Ultrastructural comparison of medial collateral ligament repair after single or multiple applications of GaAlAs laser in rats

BACKGROUND AND OBJECTIVES

To examine single versus multiple applications of a gallium aluminum arsenide (GaAlAs) laser on the ultrastructural morphology of surgically injured medial collateral ligaments (MCLs) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Sixteen rats were studied with 12 receiving right MCL transection and 4 receiving sham injury. Group 1 (n = 4) received one session of laser (31.6 J/cm(2)) immediately after injury. Group 2 (n = 4) received 9 doses of transcutaneous laser (3.5 J/cm(2)). The controls (Group 3, n = 4) received one session of placebo laser, while the sham Group 4 (n = 4) received no treatment. Ultrastructural analyses were done with electron microscopy at 3 weeks.

RESULTS

The mass-averaged diameters of collagen fibril in the core and periphery of MCLs treated with multiple laser were larger than the control and those with single laser treatment (P < 0.05). However, the sham injured group had larger fibrils than all other groups (P < 0.05).

CONCLUSIONS

The repairing MCLs had smaller collagen fibrils than the sham injured ligaments. Multiple laser treatments enhanced the collagen growth in the repairing MCLs at 3 weeks after injury, which are superior to a single treatment with similar dosage.

Photobiomodulation Improves Cutaneous Wound Healing in an Animal Model of Type II Diabetes

OBJECTIVE

We investigated the effects of photobiomodulation (PBM) on cutaneous wound healing in an animal model of type II diabetes, Psammomys obesus (Sand Rats).

BACKGROUND DATA

632-nm light has been established as the most effective wavelength for treatment of cutaneous wounds; however, the inconsistent efficacy of PBM may be due to inadequate treatment parameter selection.

METHODS

Using 632-nm light, an initial series of experiments were done to establish optimal treatment parameters for this model. Following creation of bilateral full-thickness skin wounds, non-diabetic Sand Rats were treated with PBM of differing dosages. Wound healing was assessed according to wound closure and histological characteristics of healing. Optimal treatment parameters were then used to treat type II diabetic Sand Rats while a diabetic control group received no irradiation. In order to elucidate the mechanism behind an improvement in wound healing, expression of basic fibroblast growth factor (bFGF) was assessed.

RESULTS

Significant improvement in wound healing histology and wound closure were found following treatment with 4 J/cm(2) (16 mW, 250-sec treatments for 4 consecutive days; p < 0.05). The 4 J/cm(2) dosage significantly improved histology and closure of wounds in the diabetic group in comparison to the non-irradiated diabetic group. Quantitative analysis of bFGF expression at 36 h post-injury revealed a threefold increase in the diabetic and non-diabetic Sand Rats after PBM.

CONCLUSIONS

The results demonstrate that PBM at an energy density of 4 J/cm(2) is effective in improving the healing of cutaneous wounds in an animal model of type II diabetes, suggesting that PBM (632 nm, 4 J/cm(2)) would be effective in treating chronic cutaneous wounds in diabetic patients.

Comparison of single and multiple applications of GaAlAs laser on rat medial collateral ligament repair

BACKGROUND AND OBJECTIVES

To examine single versus multiple applications of the gallium aluminum arsenide (GaAlAs) laser on the healing of surgically injured medial collateral ligaments (MCLs) in rats.

STUDY DESIGN/MATERIALS AND METHODS

Sixteen rats were studied, with 12 receiving surgical transection to their right MCL and 4 receiving a sham injury. Group 1 (n = 4) received a single dose of GaAlAs laser therapy (wavelength 660 nm, average power 8.8 mW, pulse 10 kHz, dosage 31.6 J/cm(2)) directly to their MCL during surgery. Group 2 (n = 4) received 9 doses of GaAlAs laser therapy applied transcutaneously on alternate days (wavelength 660 nm, average power 8.8 mW, pulse 10 kHz, dosage 3.5 J/cm(2)). The controls (Group 3, n = 4) received one session of placebo laser at the time of surgery, with the laser equipment shut down, while the sham injured Group 4 (n = 4) received no treatment. Biomechanical tests for structural stiffness, ultimate tensile strength (UTS), and load-relaxation were done at 3 weeks after injury. The stiffness and UTS data were normalized by expressing as a percentage of the left side of each animal before statistical analysis.

RESULTS

The load-relaxation data did not show any differences between the groups (P = 0.18). The normalized stiffness levels of Groups 2 (81.08+/-11.28%) and 4 (92.66+/-13.19%) were significantly higher (P = 0.025) than that of the control Group 3 (58.99+/-15.91%). The normalized UTS of Groups 2 (81.38+/-5.68%) and 4 (90.18+/-8.82%) were also significantly higher (P = 0.012) than that of the control (64.49+/-9.26%). Although, Group 1 had higher mean stiffness and UTS values than the control, no statistically significant difference was found between these two groups.

CONCLUSIONS

Multiple laser therapy improves the normalized strength and stiffness of repairing rat MCLs at 3 weeks after injury. The multiple treatments seem to be superior to a single treatment when the cumulative dosages are comparable between the two modes of application.

Photobiological Basis and Clinical Role of Low-Intensity Lasers in Biology and Medicine

The purpose of this article is to provide a comprehensive review on the clinical role of low intensity laser therapy (laser photostimulation) in biology and medicine. Studies on wound healing and pain relief are highlighted to show the clinical efficacy of laser therapy. Controversies about the use of low intensity laser as a therapeutic modality for wound healing and pain relief are presented and a brief explanation is provided to overcome these controversies. The importance of standard parameters is emphasized for the applications of low intensity lasers in biology and medicine. A justification has been made to warrant further research on the use of low intensity laser as a therapeutic modality. Although the therapeutic applications of low intensity laser are imminent, the heterogeneity in treatment protocols and study design calls for a vigilant interpretation of the findings.