Laser photostimulation accelerates wound healing in diabetic rats

Photobiomodulation on the Angiogenesis of Skin Wounds in Rats Using Different Light Sources

OBJECTIVE

The aim of this study was to compare the angiogenic effects of laser and light-emitting diode (LED) illumination on wounds induced in rats, with varied fluence.

BACKGROUND DATA

The LED is an alternative light source that accelerates wound healing, and its efficiency concerning the angiogenic effect was compared to low-level laser therapy (LLLT).

METHODS

The experimental model consisted of a circular wound inflicted on the quadriceps of 120 rats, using a 15-mm-diameter "punch." Animals were divided randomly into five groups: two groups of laser, with dosages of 5 and 20 J/cm(2), respectively, two groups of LED, also with dosages of 5 and 20 J/cm(2), and a control group. Six hours after wound infliction, the treated groups received the diverse applications accordingly and were irradiated every 24 h. Angiogenesis was studied through histomorphometry on days 3, 7, 14, and 21 after the wounds were inflicted.

RESULTS

On days 3, 7, and 14, the proliferation of blood vessels in all irradiated groups was superior in comparison to those of the control group (p < 0.05). Treatment with fluence of 5 J/cm(2) was better than the laser group with 20 J/cm(2) on day 21.

CONCLUSION

Red LLLT and LED demonstrated expressive results in angiogenesis. Light coherence was shown not to be essential to angiogenesis. However, further studies are needed in order to investigate the photobiomodulatory effects of LED in relation to LLLT in various biological tissues.

In Vitro Exposure of Wounded Diabetic Fibroblast Cells to a Helium-Neon Laser at 5 and 16 J/cm2

OBJECTIVE

The aim of the present investigation was to assess morphological, cellular, and molecular effects of exposing wounded diabetic fibroblast cells to He-Ne (632.8 nm) laser irradiation at two different doses.

BACKGROUND DATA

An alternative treatment modality for diabetic wound healing includes low-level laser therapy (LLLT). Although it's used in many countries and for many medical conditions, too many health care workers are unaware of this therapy, and there is still controversy surrounding its effectiveness.

METHODS

Normal human skin fibroblast cells (WS1) were used to simulate a wounded diabetic model. The effect of LLLT (632.8 nm, 5 and 16 J/cm(2) once a day on two non-consecutive days) was determined by analysis of cell morphology, cytotoxicity, apoptosis, and DNA damage.

RESULTS

Cells exposed to 5 J/cm(2) showed a higher rate of migration than cells exposed to 16 J/cm(2), and there was complete wound closure by day 4. Exposure of WS1 cells to 5 J/cm(2) on two non-consecutive days did not induce additional cytotoxicity or genetic damage, whereas exposure to 16 J/cm(2) did. There was a significant increase in apoptosis in exposed cells as compared to unexposed cells.

CONCLUSION

Based on cellular morphology, exposure to 5 J/cm(2) was stimulatory to cellular migration, whereas exposure to 16 J/cm(2) was inhibitory. Exposure to 16 J/cm(2) induced genetic damage on WS1 cells when exposed to a He-Ne laser in vitro, whereas exposure to 5 J/cm(2) did not induce any additional damage.

Low-Level Laser Therapy Enhances Wound Healing in Diabetic Rats: A Comparison of Different Lasers

OBJECTIVE

The effects of wound healing acceleration on diabetic rats were determined and compared using different laser wavelengths and incident doses.

BACKGROUND DATA

Many studies have demonstrated that low-level laser therapy (LLLT) can promote the wound healing on non-diabetic animals.

METHODS

Male Sprague-Dawley rats were used. Streptozotocin (70 mg/kg) was applied for diabetes induction. An oval full-thickness skin wound was created aseptically with a scalpel in 51 diabetic rats and six non-diabetic rats on the shaved back of the animals. The study was performed using 532, 633, 810, and 980 nm diode lasers. Incident doses of 5, 10, 20, and 30 J/cm(2) and treatment schedule of 3 times/week were used in the experiments. The area of wound on all rats was measured and plotted on a slope chart. The slope values (mm(2)/day), the percentage of relative wound healing, and the percentage of wound healing acceleration were computed in the study.

RESULTS

Mean slope values were 6.0871 in non-diabetic control and 3.636 in diabetic control rats (p > 0.005). The percentages of wound healing acceleration were 15.23, 18.06, 19.54, and 20.39 with 532-nm laser, 33.53, 38.44, 32.05, and 16.45 with 633-nm laser, 15.72, 14.94, 9.62, and 7.76 with 810-nm laser, and 12.80, 16.32, 13.79, and 7.74 with 980-nm laser, using incident doses of 5, 10, 20, and 30 J/cm(2), respectively. There were significant differences (p > 0.001) in the mean slope value of wound healing on diabetic rats between control groups and treatment groups in 532, 633, 810, and 980 nm lasers.

CONCLUSION

The wound healing on control rats with diabetes was slower than on control rats without diabetes. LLLT at appropriate treatment parameters can enhance the wound healing on diabetic rats. The optimum wavelength was 633 nm, and the optimum incident dose was 10 J/cm(2) in our study.

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

Phototherapy stimulates metabolic processes in healing wounds. Despite worldwide interest, phototherapy is not firmly established or practiced in South Africa. This study aimed to determine which dose and wavelength would better induce healing in vitro. Diabetic-induced wounded fibroblasts were irradiated with 5 or 16 J/cm(2) at 632.8, 830, or 1,064 nm. Cellular morphology, viability (Trypan blue and apoptosis), and proliferation (basic fibroblast growth factor) were then determined. Cells irradiated with 5 J/cm(2) at 632.8 nm showed complete wound closure and an increase in viability and basic fibroblast growth factor (bFGF) expression. Cells irradiated at 830 nm showed incomplete wound closure and an increase in bFGF expression. Cells irradiated at 1,064 nm showed incomplete closure and increased apoptosis. All cells irradiated with 16 J/cm(2) at all three wavelengths showed incomplete wound closure, increased apoptosis, and decreased bFGF expression. This study showed that diabetic-wounded cells respond in a dose- and a wavelength-dependent manner to laser light. Cells responded the best when irradiated with a fluence of 5 J/cm(2) at a wavelength of 632.8 nm.

Ultrastructural and autoradiographical analysis show a faster skin repair in He-Ne laser-treated wounds

There are evidences that low-intensity red laser radiation is capable to accelerate wound healing. Nowadays, this therapy has been gradually introduced in clinical practice although mechanisms underlying laser effects are poorly understood. To better understand the photobiological effects of laser radiation, this study investigated by electron microscopy, immunohistochemistry and autoradiography the morphological and functional features of irradiated and none irradiated injured mice skin. Full-thickness skin lesions were created on the back of mice and irradiated on days 1, 5, 8, 12, and 15 post-wounding with a He-Ne laser (lambda=632.8nm), dose 1J/cm(2), exposure time 3min. Non-irradiated lesions were used as a control. The mice were inoculated with (3)H-proline and sacrificed one hour after on the 8th, 15th and 22nd days to histological and radioautographical analysis. The irradiated-lesions showed a faster reepithelization compared with control lesions. The irradiated dermis contained a higher number of activated fibroblasts compared to control group and, most of them showed several cytoplasmic collagen-containing phagosomes. In irradiated-lesions, smooth muscle alpha-actin positive cells predominated, which correspond to a higher number of myofibroblasts observed in the electron microscope. Moreover, laser radiation reduced the local inflammation and appears to influence the organization of collagen fibrils in the repairing areas. Quantitative autoradiography showed that the incorporation of (3)H-proline was significantly higher in irradiated-dermis on the 15th day post-wounding (p<0.05). These results suggest that laser radiation may accelerate cutaneous wound healing in a murine model.

Short-Time Effects of Laser Needle Stimulation on the Peripheral Microcirculation Assessed by Laser Doppler Spectroscopy and Near-Infrared Spectroscopy

OBJECTIVE

The aim of the present study was to evaluate immediate effects of a standardized laser needle stimulation over a defined acupuncture point on the microvascular blood flow and muscle oxygenation in the human forearm.

BACKGROUND DATA

Recently, it has been shown that laser stimulation improves tissue perfusion. This is relevant since adequate blood supply is an important factor in the treatment of pain syndromes.

METHODS

The study was designed as a randomized, double-blinded, placebo-controlled trial. Thirty-three healthy non-smoking males were randomly assigned to a control group (n = 15) with no laser irradiation and to an intervention group (n = 18) for which laser needle irradiation was performed on the right forearm at acupuncture point Pe6. Non-invasive blood flow measurements (laser Doppler spectroscopy [LDS]) were performed before, during, and after intervention. Additionally, the dynamic changes in muscle oxygenation of the m. flexor carpi ulnaris were investigated using near-infrared spectroscopy (NIRS).

RESULTS

Repeated measures MANOVA demonstrated a statistically significant interaction between time and group (p = 0.034, effect size = 0.39), indicating that peripheral blood flow was influenced by laser needle application. In contrast, tissue oxygenation was not affected by the experimental treatment.

CONCLUSION

It has been demonstrated that laser needle stimulation may improve peripheral microcirculation under standardized conditions, whereas tissue oxygenation remained unchanged. Further research is required to determine the influence of various parameter settings and irradiation treatments on the peripheral microcirculation. Moreover, different acupuncture points should be investigated in order to appraise the clinical effectiveness of laserneedle stimulation.

Comparison between Wound Healing in Induced Diabetic and Nondiabetic Rats after Low-Level Laser Therapy

OBJECTIVE

The aim of this work was to compare the effect of low-level laser therapy (LLLT) on the wound healing process in nondiabetic and diabetic rats.

BACKGROUND DATA

Among the clinical symptoms caused by diabetes mellitus, a delay in wound healing is a potential risk for patients. It is suggested that LLLT can improve wound healing.

METHODS

The tissue used for this study was extracted from animals suffering from diabetes, which was induced by Streptozotocin, and from nondiabetic rats. Animals were assembled into two groups of 25 rats each (treated and control) and further subdivided into two groups: diabetic (n = 15) and nondiabetic (n = 10). A full-thickness skin wound was made on the dorsum area, with a round 8-mm holepunch. The treated group was irradiated by a HeNe laser at 632.8 nm, with the following parameters: 15 mW, exposition time of 17 sec, 0.025 cm2 irradiated area, and energy density of 10 J/cm2. Square full-thickness skin samples (18 mm each side, including both injured and noninjured tissues) were obtained at 4, 7, and 15 days after surgery and analyzed by qualitative and quantitative histological methods.

RESULTS

Quantitative histopathological analysis confirmed the results of the qualitative analysis through histological microscope slides. When comparing tissue components (inflammatory cells, vessels and fibroblast/area), we found that treated animals had a less intense inflammatory process than controls.

CONCLUSION

Results obtained by both qualitative and quantitative analyses suggested that irradiation of rats with HeNe (632.8 nm), at the tested dose, promoted efficient wound healing in both nondiabetic and diabetic rats as, compared to the control group.

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.

Emerging Modalities in Veterinary Rehabilitation

Many new modalities have been introduced in human and veterinary physical rehabilitation. In many instances, there is sound theory of how they may impact the physiology of various cells, tissues, or organs. This article reviews some of the modalities that have been introduced recently in human and veterinary rehabilitation. Topics include low-level laser, phototherapy, and extracorporeal shock wave treatment.

Principles of early wound management

The equine practitioner can positively influence wound healing by dispensing appropriate treatment in the first few hours after injury. Positive actions in the early period include hemostasis, meticulous cleansing and debridement of the wound, the use of effective but nonirritating products to disinfect the wound, closure (if indicated)with minimal tension on the suture line, the judicious use of drains,and ensuring adequate tetanus protection. Furthermore, a thorough assessment of the wound and the patient in the initial period after trauma provides pertinent information on prognosis. Finally,good communication and cooperation among all involved parties are necessary to ensure that everyone understands the factors involved and the potential for a successful outcome.

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.

Effect of Low Intensity Helium-Neon (He-Ne) Laser Irradiation on Diabetic Wound Healing Dynamics

OBJECTIVE

The aim of this study was to determine the effect of low-energy He-Ne laser treatment on wound healing dynamics (histological and biochemical) in diabetic rats.

BACKGROUND DATA

Low-energy laser photostimulation at certain wavelengths can enhance tissue repair by releasing growth factors from fibroblasts and can facilitate the healing process of diabetic wounds.

MATERIALS AND METHODS

A circular 4 cm2 excisional wound was created on the dorsum of the experimentally (Alloxan)-induced diabetic rats. In the study group (N = 24) the wound was treated with He-Ne laser (632.8 nm wavelength) at a dose of 4.8 J/cm2 for 5 days a week until the wound healed completely. The control group (N = 24) was sham-irradiated. The results were statistically analyzed by an independent t test for biochemical analysis and the nonparametric Mann-Whitney U test for histopathological parameters.

RESULTS

The analysis of the biochemical parameters and histopathological parameters of the wounds showed that the laser-treated group healed faster and better as compared to the control group (p < 0.0001). The laser-treated group healed on average by the 18th day whereas, the control group healed on average by the 59th day.

CONCLUSION

Laser photostimulation promotes the tissue repair process of diabetic wounds.

AGE-related cross-linking of collagen is associated with aortic wall matrix stiffness in the pathogenesis of drug-induced diabetes in rats

Diabetes mellitus is major risk factor for cardiovascular disease, and atherosclerosis accounts for most of the morbidity and mortality of diabetic patients. To examine the effects of diabetes on the vessel wall, we examined the association of collagen cross-linking in relation to matrix stiffness of the descending aorta in streptozotocin-induced diabetic rats. The matrix stiffness of the vessel was determined by measuring the tensile properties of the tissue. Seven weeks following the establishment of diabetes, both control and diabetic rats were killed and the descending aortas were excised and analyzed. The findings from biomechanical analysis indicated a significant increase in maximum load (26%), stress (22%), Young's modulus of elasticity (60%), and toughness (32%) in diabetic aortas compared to control. In contrast, the maximum strain of the diabetic rat aorta was significantly reduced by 20% compared to control rats, suggesting stiffening of the blood vessel. The results from biochemical analysis showed that the amount of total collagen increased by 21% in diabetic tissues compared to the control. The sequential extractions of collagen showed that the diabetic specimens yielded 34% more neutral salt-soluble collagen (NSC) than the control. The amount of pepsin-soluble collagen was 31% less in diabetic tissues than in the control group, whereas the amount of insoluble collagen (ISC) increased by 56%. A significant accumulation in advanced glycation end products (AGEs) were seen in pepsin- and collagenase-soluble collagen in diabetic vessel. Furthermore, the altered biomechanical properties of the vessel wall were strongly correlated with the biochemistry of collagen. Overall, these results provide evidence that the diabetic state is associated with the changes in collagen biochemistry and in the biomechanics of the blood vessel.

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.

Effect of a diode laser on wound healing by using diabetic and nondiabetic mice

The purpose of this study was to evaluate a 980-nm gallium-aluminum-arsenide diode laser for wound healing. Using genetically diabetic and nondiabetic mice, two 6-mm wounds were created on the back of each mouse by using a punch biopsy. The mice were assigned to 1 of 4 subgroups for laser treatment at different fluence and frequency of treatment: 5 W (18 J/cm2) every 2 days, 5 W (18 J/cm2) every 4 days, 10 W (36 J/cm2) every 2 days, and 10 W (36 J/cm2) every 4 days. In addition, control mice were used and the wounds were allowed to heal naturally. Wound healing was evaluated on days 5, 12, and 19 by percentage of wounds healed and percent wound closure. A maximum of 5 mice per subgroup were killed at days 7, 14, and 21, and histology was conducted on the wound sites. For diabetic mice receiving 5 W every 2 days, the percentage of wounds healed after 19 days was 100% versus 40% in the control group. Only 20% of wounds in the 10-W diabetic subgroups achieved healing during the same period. For the subgroups whose wounds did not completely heal, all but the 10 W every 2 days subgroup had average closure of >90%. The 100% closure for the 5 W every 2 days subgroup was significantly greater than the other subgroups. For nondiabetic mice, 100% of the wounds in the 5 W every 4 days and control subgroups were completely healed, whereas 90% of the wounds from the 5 W every 2 days and the 10 W every 4 days subgroups were completely healed. In the latter 2 subgroups, wound closure was 99.4% and 98.8%, respectively. These differences were not significant. The histologic results confirmed these findings. In conclusion, treatment at 18 J/cm2 shows a beneficial effect on wound healing in diabetic mice and does not have a detrimental effect in nondiabetic mice.

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.

Comparison of the photostimulatory effects of visible He-Ne and infrared Ga-As lasers on healing impaired diabetic rat wounds

BACKGROUND AND OBJECTIVES

In this study, the ability of photostimulation to promote healing of impaired wounds was investigated using a Ga-As laser in rats with experimental diabetes and the results were compared with previously reported findings of the effects of a He-Ne laser on the repair of healing-impaired diabetic rat wounds 1.

STUDY DESIGN/MATERIALS AND METHODS

Diabetes was induced in male rats by streptozotocin injection following which two full thickness punch wounds of 6-mm diameter were created in the skin, one on either side of the spine of each animal. The left wound of each animal was treated with infrared radiation at 904 nm produced by a Ga-As laser at an energy density of 1.0 J/cm(2). The right wound of each animal served as the control. The wounds were treated with a laser 5 days a week for 3 weeks. Following animal sacrifice, the strips of skin containing the wound sites were collected and analyzed.

RESULTS

The results from the biomechanical analysis indicated that the Ga-As laser used in this study significantly increased wound tensile strain and toughness compared to the control wounds. Marginal increases in wound tensile strength (9%) and stress (7%) were observed in the Ga-As laser-treated wounds compared to the controls. No significant changes were found in Young's modulus and energy absorption capacity between the control and laser-treated wounds. Analysis of wound collagen revealed a significant increases in total collagen (14%), salt soluble collagen (31%), acid soluble (14%), and insoluble collagen (50%) with simultaneous decrease in pepsin soluble collagen (19%) in the Ga-As laser-treated wounds compared to controls. Comparisons of these results with the earlier findings revealed that the He-Ne laser appears to be superior to the Ga-As laser, at the parameters of treatment tested, in promoting the wound healing in diabetic rats.

CONCLUSIONS

The differences in stimulatory effects noted between the He-Ne and Ga-As lasers suggest that the photochemical response the cells for each laser may depend on the wavelength and coherent properties of the electromagnetic radiation.

cDNA microarray analysis of gene expression profiles in human fibroblast cells irradiated with red light

In this paper, the cDNA microarray technique was used to investigate the gene expression profiles of human fibroblasts irradiated by low-intensity red light. Proliferation assays showed that the fibroblast HS27 cells responded with a curve effect to different doses of low-intensity red light irradiation at a wavelength of 628 nm. An optimal dose of 0.88 J per cm2 was chosen for subsequent cDNA microarray experiments. The gene expression profiles revealed that 111 genes were regulated by the red light irradiation and can be grouped into 10 functional categories. Most of these genes directly or indirectly play roles in the enhancement of cell proliferation and the suppression of apoptosis. Two signaling pathways, the p38 mitogen-activated protein kinase signaling pathway and the platelet-derived growth factor signaling pathway, were found to be involved in cell growth induced by irradiation of low-intensity red light. Several genes related to antioxidation and mitochondria energy metabolism were also found to express differentially upon irradiation. This study provides insight into the molecular mechanisms associated with the beneficial effects of red light irradiation in accelerating wound healing.