Diabetic Rats – Phototherapeutic Effects

Acta Cir Bras. 2016 Aug;31(8):498-504. doi: 10.1590/S0102-865020160080000001.

The effects of photobiomodulation therapy on Staphylococcus aureus infected surgical wounds in diabetic rats. A microbiological, histopathological, and biomechanical study.

Ranjbar R1, Takhtfooladi MA2.

Author information

  • 1Full professor, Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran. Design and supervised all phases of the study.
  • 2PhD, Young Researchers and Elites Club, Science and Research Branch, Islamic Azad University, Tehran, Iran. Conception and design of the study; acquisition, analysis and interpretation of data; statistical analysis; manuscript writing.



To evaluate the effects of photobiomodulation therapy (PBMT) at 685 nm on diabetic wound healing in rats suffering from bacterial infection induced by Staphylococcus aureus (S. aureus).


Thirty streptozotocin-induced diabetic rats were allocated into two groups: control and PBMT. A 4-cm full-thickness linear-incision was made on the dorsal midline and was contaminated with S. aureus. The wounds in the PBMT group were irradiated daily for 5 consecutive days, starting 3 days after the induction and always in the mornings.


The result revealed that PBMT resulted in a significant decrease in S. aureus CFU in the PBMT group in comparison to the control group (P<0.05). The length of wounds, in the 2nd and 3rd weeks, in the PBMT group were significantly shorter compared to the control group (P<0.05). PBMT caused a significant increase in the histological parameters in comparison to the control group (P<0.05). Moreover, PBMT significantly increased the breaking strength of the surgical scars produced in the skin of the PBMT group when compared to the control group (P<0.05).


Photobiomodulation therapy may be useful in the management of wound infection through a significant bacterial growth inhibition and an acceleration of wound healing process.

Lasers Med Sci. 2015 Jul 30. [Epub ahead of print]

Photobiomodulation and bone healing in diabetic rats: evaluation of bone response using a tibial defect experimental model.

Magri AM1, Fernandes KR, Assis L, Mendes NA, da Silva Santos AL, de Oliveira Dantas E, Rennó AC.

Author information

  • 1Department of Biosciences, Federal University of São Paulo, Av. Ana Costa, 95, Vila Mathias, Santos, 11060-001, São Paulo, Brazil.


Diabetes mellitus (DM) leads to a delay in bone healing. Thus, some therapeutic approaches have been used to accelerate the process of bone repair such as photobiomodulation (PBM). Therefore, the present study aimed to evaluate the effects of PBM, in different fluences, in bone repair in an experimental model of tibial bone defects in diabetic rats. Sixty-four Wistar rats were submitted to a surgical procedure to perform bone defect and distributed in four groups: diabetic control group (DCG), diabetic laser group 30 J/cm2 (L30), diabetic laser group 60 J/cm2 (L60), and diabetic laser group 120 J/cm2 (L120). A 808 nm Ga-Al-As (DMC Equipment, São Carlos, SP, Brazil) laser, 100 mW; 0.028 cm2; 3.57 W/cm2; 30, 60, and 120 J/cm2; 0.84, 1.68, and 3.36 J; 8, 16, and 33 s was used. Animals were euthanized 15 and 30 days after the surgery. Histological, morphometric, immunohistochemistry, and biomechanical analyses were performed. In the histological and morphometric evaluation, all laser-treated groups showed a better histological pattern and a higher amount of newly formed bone compared to DCG. An intense RUNX2 immunoexpression was observed in the laser-treated groups, 15 days after the surgery. Receptor activator of nuclear factor ?-? ligand (RANK-L) immunohistochemistry analysis showed a significant decrease in the immunoreactivity for L30 and L120, 30 days after surgery. There was no statistical difference in the biomechanical analysis among the groups. In conclusion, PBM, in all fluences used, showed an osteogenic potential in bone healing of diabetic rats.

Photomed Laser Surg.  2013 Jul;31(7):315-21. doi: 10.1089/pho.2012.3406. Epub 2013 Jun 21.

The effects of low-level laser therapy on palatal mucoperiosteal wound healing and oxidative stress status in experimental diabetic rats.

Firat ET1, Da A, Günay A, Kaya B, Karadede M, Kanay BE, Ketani A, Evliyaolu O, Uysal E.
  • 1Department of Periodontology, Faculty of Dentistry, Dicle University, Diyarbakir, Turkey. elakadiroglu@hotmail.com



The biostimulation effects of low-level laser therapy (LLLT) have recently been demonstrated. In this study, we aimed to investigate the effects of LLLT on palatal mucoperiostal wound healing and oxidative stress status in experimental diabetic rats.


Forty-two male Wistar rats that weighed 250-300g were used in this study. Experimental diabetes was induced in all of the rats using streptozotocin. A standardized full thickness wound was made in the mucoperiosteum of the hard palates of the rats using a 3mm biopsy punch. The rats were divided into groups: 1 (control group, non- irradiated), and 2 (experimental group, irradiated). Treatment using a GaAlAs laser at a wavelength of 940 nm and at dose of 10 J/cm(2) began after surgery, and was repeated on the 2nd, 4th, and 6th days post-surgery. Seven animals from each group were killed on the 7th, 14th, and 21st day after surgery. Biopsies were performed for the histological analysis and blood samples were collected by cardiac puncture for biochemical analysis.


The histopathological findings revealed reduced numbers of inflammatory cells, and increased mitotic activity of fibroblasts, collagen synthesis, and vascularization in rats in group 2. The total oxidative status was significantly decreased in the laser-treated group on the 21st day.


LLLT elicits a positive healing effect on palatal mucoperiostal wounds, and modulates the oxidative status in experimental diabetic rats.

Lasers Med Sci.  2012 Dec 22. [Epub ahead of print]

Effect of laser therapy on skeletal muscle repair process in diabetic rats.

França CM, de Loura Santana C, Takahashi CB, Alves AN, De Souza Mernick AP, Fernandes KP, de Fátima Teixeira da Silva D, Bussadori SK, Mesquita-Ferrari RA.


Postgraduate Program in Biophotonics Applied to Health Sciences, Universidade Nove de Julho, São Paulo, São Paulo, Brazil, 01504-001, cristiane321@gmail.com.


Skeletal muscle myopathy is a common source of disability in diabetic patients. This study evaluated whether low-level laser therapy (LLLT) influences the healing morphology of injured skeletal muscle. Sixty-five male Wistar rats were divided as follows: (1) sham; (2) control; (3) diabetic; (4) diabetic sham; (5) nondiabetic cryoinjured submitted to LLLT (LLLT); (6) diabetic cryoinjured submitted to LLLT (D-LLLT); and (7) diabetic cryoinjured non-treated (D). Diabetes was induced with streptozotocin. Anterior tibialis muscle was cryoinjured and received LLLT daily (780 nm, 5 J/cm(2), 10 s per point; 0.2 J; total treatment, 1.6 J). Euthanasia occurred on day 1 in groups 1, 2, 3, and 4 and on days 1, 7, and 14 in groups 5, 6, and 7. Muscle samples were processed for H&E and Picrosirius Red and photographed. Leukocytes, myonecrosis, fibrosis, and immature fibers were manually quantified using the ImageJ software. On day 1, all cryoinjured groups were in the inflammatory phase. The D group exhibited more myonecrosis than LLLT group (p?<?0.05). On day 14, the LLLT group was in the remodeling phase; the D group was still in the proliferative phase, with fibrosis, chronic inflammation, and granulation tissue; and the D-LLLT group was in an intermediary state in relation to the two previous groups. Under polarized light, on day 14, the LLLT and D-LLLT groups had organized collagen bundles in the perimysium, whereas the diabetic groups exhibited fibrosis. LLLT can have a positive effect on the morphology of skeletal muscle during the tissue repair process by enhancing the reorganization of myofibers and the perimysium, reducing fibrosis.

Lasers Surg Med.  2010 Nov;42(9):656-64.

Laser photobiostimulation of wound healing: defining a dose response for splinted wounds in diabetic mice.

Chung TY, Peplow PV, Baxter GD.

Department of Anatomy & Structural Biology, University of Otago, Dunedin, New Zealand.


BACKGROUND AND OBJECTIVES: We have used a 660 nm, 80 mW laser diode in genetic diabetic mice to stimulate the healing of wounds covered with a Tegaderm HP dressing that causes a retardation of contraction (splinted wounds). The purpose of our study was to examine the effects of irradiating the wounds for different time intervals in order to determine a dose response relationship.

MATERIALS AND METHODS: A circular excisional wound was made on the left flank of diabetic mice using a 5-mm skin punch, and covered with a Tegaderm HP dressing. Mice were allocated to four groups in which wounds were irradiated 660 nm, 80 mW for 0, 10, 20, or 40 seconds each day for 7 days. In total, 51 mice were used. Wounds were harvested on day 14 and the healing assessed from hematoxylin-eosin stained sections examined by light microscopy.

RESULTS: The wounds were splinted in 40 of the mice, and splinting caused a retardation of healing. The findings for the four treatments showed that irradiation for 20 second/day for 7 days brought about the greatest extent of healing. The wounds healed mainly by re-epithelization and granulation tissue formation. This duration of irradiation represents an energy dose of 1.6 J per irradiation and, for an estimated area of irradiation of 32-43 mm², corresponds to an energy density of 3.7-5.0 J/cm².

CONCLUSION: Irradiation with 660 nm, 80 mW at an energy density of 3.7-5.0 J/cm² each day for 7 days caused the maximal stimulation of healing in splinted wounds of diabetic mice.

Photomed Laser Surg. 2010 Aug;28(4):483-8.

Influence of the use of laser phototherapy (lambda660 or 790 nm) on the survival of cutaneous flaps on diabetic rats.

Santos NR, dos Santos JN, dos Reis JA Jr, Oliveira PC, de Sousa AP, de Carvalho CM, Soares LG, Marques AM, Pinheiro AL.

School of Dentistry, Federal University of Bahia, Salvador, Bahia, Brazil.


OBJECTIVE: The aim of this study was to assess and compare the effects of laser phototherapy (LPT) on cutaneous flaps on diabetic rats.

BACKGROUND: Diabetes mellitus is characterized by high blood glucose levels. Its main complications are delayed wound healing, an impaired blood supply, and a decrease in collagen production. Cutaneous flaps are routinely used in several surgical procedures, and most failures are related to poor blood supply. LPT has been studied using several healing models.

ANIMALS AND METHODS: Twelve Wistar rats were randomized into three groups: group 1 (G1; diabetic animals without treatment), group 2 (G2; diabetic animals irradiated with lambda680 nm), and group 3 (G3; diabetic animals irradiated with lambda790 nm). Diabetes was induced with streptozotocin. A 2- x 8-cm cutaneous flap was raised on the dorsum of each animal, and a plastic sheet was introduced between the flap and the bed to cause poor blood supply. Nonirradiated animals acted as controls. The dose per session was 40 J/cm(2). Laser light was applied transcutaneously and fractioned on 16 contact points at the wound margins (16 x 2.5 J/cm(2)). Animal death occurred on day 8 after surgery. Specimens were taken, processed, cut, stained with eosin (HE) and sirius red, and underwent histological analysis.

RESULTS: It is shown that accute inflammation was mostly discrete for G3. Chronic inflammation was more evident for G2. Fibroblast number was higher for G3. Angiogenesis was more evident for G3. Necrosis was more evident for G2. Statistical analysis among all groups showed significant differences (p = 0.04) on the level of acute inflammation between G1 and G3, tissue necrosis between G1 and G2 (p = 0.03), chronic inflammation between (p = 0.04), fibroblastic proliferation between G2 and G3 (p = 0.05), and neovascularization between G2 and G3 (p = 0.04).

CONCLUSION: LPT was effective in increasing angiogenesis as seen on irradiated subjects and was more pronounced when IR laser light was used.

J Photochem Photobiol B. 2010 May 3;99(2):105-10. Epub 2010 Mar 11.

Effects of low-level light therapy on streptozotocin-induced diabetic kidney.

Lim J, Sanders RA, Snyder AC, Eells JT, Henshel DS, Watkins JB 3rd.

School of Public and Environmental Affairs, Indiana University, 1315 East Tenth Street, Bloomington, IN 47405, United States.


Hyperglycemia causes oxidative damage in tissues prone to complications in diabetes. Low-level light therapy (LLLT) in the red to near infrared range (630-1000nm) has been shown to accelerate diabetic wound healing. To test the hypothesis that LLLT would attenuate oxidative renal damage in Type I diabetic rats, male Wistar rats were made diabetic with streptozotocin (50mg/kg, ip), and then exposed to 670nm light at a dose of 9J/cm(2) once per day for 14weeks. The activity and expression of catalase and the activity of Na K-ATPase increased in kidneys of light-treated diabetic rats, whereas the activity and expression of glutathione peroxidase and the expression of Na K-ATPase were unchanged. LLLT lowered the values of serum BUN, serum creatinine, and BUN/creatinine ratio. In addition, LLLT augmented the activity and expression of cytochrome c oxidase, a primary photoacceptor molecule in the mitochondrial respiratory chain, and reduced the formation of the DNA adduct 8-hydroxy-2′-deoxyguanosine in kidney. LLLT improved renal function and antioxidant defense capabilities in the kidney of Type I diabetic rats. Thus, 670nm LLLT may be broadly applicable to the amelioration of renal complications induced by diabetes that disrupt antioxidant defense mechanisms.

Photomed Laser Surg. 2009 Oct 27. [Epub ahead of print]

Effect of Biostimulation on Healing of Bone Defects in Diabetic Rats.

Akyol UK, Güngörmü? M.

Ataturk University , Faculty of Dentistry, Department of Oral and Maxillofacial Surgery, Erzurum, Turkey .

Abstract Background and Objective: The aim of this study was to investigate the effects of biostimulation on healing of bone defects in diabetic rats. Study Design/Material and Methods: Twenty-eight Wistar rats weighting 250 to 300 g were used for this study. Diabetes was chemically induced with streptozotocin, and 14 nondiabetic and 14 diabetic rats were included in the study. The distal epiphysis of the right and left femurs of the diabetic rats were perforated with a surgical bone drill. This surgical procedure was performed on the left femurs of normal rats too. The wound on the right side of each diabetic rat received laser stimulation. The left femur of each nondiabetic (normal) rat served as a control. The rats were assigned to three experimental groups: (1) normal bur (control group); (2) diabetic bur; (3) diabetic bur + biostimulation. Results: There was a significant difference among all groups in substantia spongiosa formation on day 10. According to the Mann-Whitney U test, there was a difference between Groups 1 and 2. A significant difference was noted between Groups 2 and 3 as well as between Groups 1 and 3 and between Groups 2 and 3 in union at 20 d of healing. Conclusions: Substantia spongiosa formation was slightly more evident in Groups 1 and 3 than in Group 2. Also, there was more union in Group 3 than in the other groups on day 20. As a result, it can be concluded that low-level laser therapy (808 nm laser at 10 J/cm(2)) can have a beneficial effect on spongiosa in diabetic bone repair when five treatments are administered with 2 d intervals between treatments.

Photomed Laser Surg. 2009 Oct;27(5):703-8.

The effects of low-level laser therapy on bone in diabetic and nondiabetic rats.

Bayat M, Abdi S, Javadieh F, Mohsenifar Z, Rashid MR.

Cellular and Molecular Biology Research Center, Medical Faculty, Shahid Beheshti University, MC, Tehran, Iran. bayat_m@yahoo.com

OBJECTIVE: The aim of the present study was to examine the effects of low-level laser therapy (LLLT) on the tibia of streptozotocin-induced diabetic (STZ-D) rats. BACKGROUND DATA: LLLT has been found to accelerate fracture healing in animals. Diabetes mellitus decreases bone volume and its biomechanical parameters. MATERIALS AND METHODS: Twenty rats were divided randomly into four groups. Rats in the first two groups were administrated a single injection of STZ to induce diabetes, while animals in groups 3 and 4 were given a sham injection of distilled water. The right tibia in groups 1 and 2 was treated with a He-Ne laser (632.8 nm, 10 mW) of 28.6 and 382.2 J/cm(2), respectively. LLLT was performed daily for 14 consecutive days. The right tibia of rats in group 3 was treated with LLLT the same as group 2. The right tibia of rats in group 4 was used for based line studies. After 14 d, right tibiae and left tibiae (control bone) were extracted and subjected to the three-point bending test and histological study. RESULTS: Maximum force (N) was significantly greater in laser-treated bones of groups 2 and 3 compared with their relevant control groups (paired Student t test, p = 0.05 and p = 0.007, respectively). Density of the bone lamella meshwork of compact bone in group 2 was significantly greater in comparison with its control group (paired Student t test, p = 0.005). CONCLUSION: LLLT on tibia of STZ-D rats increased the bone lamella meshwork density of compact bone and also increased its strength.

Photomed Laser Surg. 2009 Aug;27(4):641-6.

The effects of infrared low-level laser therapy on healing of partial osteotomy of tibia in streptozotocin-induced diabetic rats.

Javadieh F, Bayat M, Abdi S, Mohsenifar Z, Razi S.

Anatomy Department, Medical Faculty, Shahid Beheshti University, MC, Tehran, Iran.

OBJECTIVE: The effects of low-level laser therapy (LLLT) on a bone defect model in streptozotocin-induced diabetic (STZ-D) rats was examined. BACKGROUND DATA: LLLT accelerates bone fracture repair in healthy animals, but its effect in diabetic animals is unclear. METHODS: Twenty-eight rats were divided into five groups: 1 (diabetes, no LLLT), 2 (diabetes, LLLT high dose), 3 (diabetes, LLLT low dose), 4 (no diabetes, no LLLT), and 5 (no diabetes, LLLT low dose) Diabetes was induced by a single injection of STZ in rats of groups 1, 2, and 3. A bone defect was made in the right tibia of rats in all groups. The defect in groups 2, 3, and 5 was treated with LLLT (890 nm, 70 W, 3000 Hz, circular beam shape, and 1 cm(2) spot size). Doses of 23.3 J/cm(2) (530 s) for group 2 and 11.6 J/cm(2) (265 s) for groups 3 and 5 were applied three times a week. The right tibias were collected 42 days after surgery and subjected to three-point bending test on a material testing machine (MTM) until fracture occurred. Data was automatically recorded on the MTM formed the load-deformation curve. RESULTS: Mann-Whitney test showed that LLLT with 11.6 J/cm(2) significantly increased bending stiffness and maximum force in diabetic rats compared with group 1 (both p = 0.041). CONCLUSION: LLLT in an experimental diabetic model enhanced bone repair with a higher bending stiffness and maximum force compared to the control group.

Photomed Laser Surg. 2009 Aug;27(4):607-10.

Effect of biostimulation on wound healing in diabetic rats.

Güngörmü? M, Akyol UK.

Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Ataturk University, Erzurum, Turkey. gungormusm@yahoo.com

BACKGROUND AND OBJECTIVE: Impaired wound healing is a complication of diabetes and is a serious problem in clinical practice. The purpose of this study was to evaluate the effect of biostimulation on wound healing in diabetic rats. MATERIAL AND METHODS: Thirty-six female Wistar rats weighting 250 to 300 g were used for this study. Diabetes was chemically induced with streptozotocin. Eighteen nondiabetic and 18 diabetic rats were included in the analysis. One incision was performed on the dorsum of each nondiabetic rat and the wound served as a control. Two parallel incisions were performed on the dorsum of each diabetic rat. The laser treatments were started immediately after surgery and were repeated on the second, fourth, sixth, and eighth days. A GaAlAs laser was used with an 808 nm wavelength. One wound of each diabetic rat received 10 J/cm(2) laser stimulation. RESULTS: Inflammation and re-epithelialization were evaluated in all groups, and there was a significant difference between the nondiabetic scalpel, diabetic scalpel, and diabetic scalpel + biostimulation groups. CONCLUSIONS: Treatment with laser biostimulation showed a beneficial effect on wound healing in diabetic rats. It can be concluded that low-level laser therapy (808 nm laser at 10 J/cm(2)) can have a beneficial effect on diabetic wound healing, when used at 2 d intervals over 5 d.

Lasers Med Sci. 2009 Jul;24(4):591-6. Epub 2008 Nov 4.

Effect of diode laser on enzymatic activity of parotid glands of diabetic rats.

Simões A, Ganzerla E, Yamaguti PM, de Paula Eduardo C, Nicolau J.

Oral Biology Research Center, Biomaterials and Oral Biochemistry Department, Faculty of Dentistry, University of São Paulo (USP), São Paulo, Brazil. lysimoes@usp.br

The aim of this study was to evaluate the effect of laser irradiation (LI) on enzymatic activities of amylase, catalase and peroxidase in the parotid glands (PG) of diabetic and non-diabetic rats. Ninety-six female rats were divided into eight groups: D0; D5; D10; D20 and C0; C5; C10; C20, respectively. Diabetes was induced by administration of streptozotocin and confirmed later by the glycemia results. Twenty-nine (29) days after the induction, the PGs of groups D5 and C5; D10 and C10; D20 and C20, were irradiated with 5 J/cm(2), 10 J/cm(2) and 20 J/cm(2) of laser diode (660 nm/100 mW) respectively. On the following day, the rats were euthanized and the enzymatic activity in the PGs was measured. Diabetic rats that had not been irradiated (group D0) showed higher catalase activity (P < 0.05) than those in group C0 (0.14 +/- 0.02 U/mg protein and 0.10 +/- 0.03 U/mg protein, respectively). However, laser irradiation of 5 J/cm(2) and 20 J/cm(2) decreased the catalase activity of the diabetic groups (D5 and D20) to non-diabetic values (P > 0.05). Based on the results of this study, LI decreased catalase activity in the PGs of diabetic rats.

Photomed Laser Surg. 2009 Feb 4. [Epub ahead of print]

Laser Therapy Converts Diabetic Wound Healing to Normal Healing.

Al-Watban FA.

Laser Medicine Research Section, Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia.

Abstract Objective: We have determined optimal laser dosimetric parameters in comparison with polychromatic light-emitting diodes (LEDs) that can speed up healing in four animal models: non-diabetic oval full-thickness wounds, diabetic oval full-thickness wounds, non-diabetic burns, and diabetic burns in Sprague-Dawley rats. Materials and Methods: This series of studies used 532-, 633-, 810-, 980-, and 10,600-nm lasers (visible to far infrared) and polychromatic LED clusters (510-872 nm, visible to infrared) as photon sources. Sprague-Dawley rats (n = 893) were used; however, animals that died before and during the experiments from anesthesia accidents and for any other reason were excluded from statistical analysis. Results: The improvements seen (>10% improvement of impairment) show that phototherapy with the 633-nm laser is quite promising for alleviating diabetic wound and burn healing, and exhibited the best results with 38.5% and 53.4% improvements, respectively. Conclusion: In this induced-diabetes model, wound and burn healing were improved by 40.3% and 45%, respectively, in 633-nm laser dosimetry experiments, and diabetic wound and burn healing was accelerated by phototherapy. This indicates that the healing rate was normalized in the phototherapy-treated diabetic rats. In view of these interesting findings, 633-nm laser therapy given three times per week at 4.71 J/cm(2) per dose for diabetic burns, and three times per week at 2.35 J/cm(2) per dose for diabetic wound healing are recommended as actual doses for human clinical trials, especially after major surgery in those with impaired healing, such as diabetics and the elderly.

J Biochem Mol Toxicol. 2009 Jan;23(1):1-8.

Effects of low-level light therapy on hepatic antioxidant defense in acute and chronic diabetic rats.

Lim J, Ali ZM, Sanders RA, Snyder AC, Eells JT, Henshel DS, Watkins JB 3rd.

School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405, USA.


Diabetes causes oxidative stress in the liver and other tissues prone to complications. Photobiomodulation by near infrared light (670 nm) has been shown to accelerate diabetic wound healing, improve recovery from oxidative injury in the kidney, and attenuate degeneration in retina and optic nerve. The present study tested the hypothesis that 670 nm photobiomodulation, a low-level light therapy, would attenuate oxidative stress and enhance the antioxidant protection system in the liver of a model of type I diabetes. Male Wistar rats were made diabetic with streptozotocin (50 mg/kg, ip) then exposed to 670 nm light (9 J/cm(2)) once per day for 18 days (acute) or 14 weeks (chronic). Livers were harvested, flash frozen, and then assayed for markers of oxidative stress. Light treatment was ineffective as an antioxidant therapy in chronic diabetes, but light treatment for 18 days in acutely diabetic rats resulted in the normalization of hepatic glutathione reductase and superoxide dismutase activities and a significant increase in glutathione peroxidase and glutathione-S transferase activities. The results of this study suggest that 670 nm photobiomodulation may reduce, at least in part, acute hepatic oxidative stress by enhancing the antioxidant defense system in the diabetic rat model.

J Periodontol. 2008 Nov;79(11):2156-65.

Treatment of experimental periodontal disease by photodynamic therapy in rats with diabetes.

de Almeida JM, Theodoro LH, Bosco AF, Nagata MJ, Bonfante S, Garcia VG.

Department of Surgery and Integrated Clinic, São Paulo State University, Araçatuba, SP, Brazil.

BACKGROUND: The aim of this study was to evaluate histologically and histometrically the influence of photodynamic therapy (PDT) as an adjuvant treatment on induced periodontitis in rats with diabetes. METHODS: Two hundred forty rats were divided evenly into two groups: non-diabetic (ND; n = 120) and alloxan diabetic (D; n = 120). Periodontal disease was induced in both groups at the first mandibular molar. After 7 days, the ligature was removed, and all animals underwent scaling and root planing (SRP) and were divided according to the following treatments: irrigation with saline solution (SRP); irrigation with a phenothiazinium dye (100 microg/ml) (TBO); laser irradiation (660 nm, 24 J) (LLLT); and PDT (TBO and laser irradiation). Ten animals in each experimental group and treatment subgroup were euthanized at 7, 15, and 30 days. The histometric values were analyzed statistically (P <0.05). RESULTS: In the ND group, the animals treated by PDT showed less bone loss (0.33 +/- 0.05 mm(2), 0.35 +/- 0.06 mm(2), and 0.27 +/- 0.07 mm(2) at 7, 15, and 30 days, respectively; P <0.05) at all experimental periods than the SRP group (1.11 +/- 0.11 mm(2), 0.84 +/- 0.12 mm(2), and 0.97 +/- 0.13 mm(2) at 7, 15, and 30 days, respectively), the TBO group (0.51 +/- 0.12 mm(2), 0.70 +/- 0.13 mm(2), and 0.64 +/- 0.08 mm(2) at 7, 15, and 30 days, respectively), and the LLLT group (0.59 +/- 0.03 mm(2), 0.61 +/- 0.04 mm(2), and 0.60 +/- 0.03 mm(2) at 7, 15, and 30 days, respectively). In the D group, the animals treated by PDT showed less bone loss (0.29 +/- 0.03 mm(2), 0.24 +/- 0.02 mm(2), and 0.27 +/- 0.06 mm(2) at 7, 15, and 30 days, respectively; P <0.05) at all experimental periods than the SRP group (2.27 +/- 0.47 mm(2), 3.23 +/- 0.34 mm(2), and 2.82 +/- 0.75 mm(2) at 7, 15, and 30 days, respectively), the TBO group (0.51 +/- 0.15 mm(2), 0.44 +/- 0.07 mm(2), and 0.57 +/- 0.13 mm(2) at 7, 15, and 30 days, respectively), and the LLLT group (0.37 +/- 0.05 mm(2), 0.35 +/- 0.09 mm(2), and 0.39 +/- 0.12 mm(2) at 7, 15, and 30 days, respectively). CONCLUSION: PDT was a beneficial adjuvant treatment for periodontal diseases induced by bacterial plaque and systemically modified by diabetes mellitus.

Photomed Laser Surg. 2009 Apr;27(2):269-72.

Visible lasers were better than invisible lasers in accelerating burn healing on diabetic rats.

Al-Watban FA, Zhang XY, Andres BL, Al-Anize A.

Laser Research Section, Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia. watban@kfshrc.edu.sa

OBJECTIVE: This study was designed to assess and compare the efficacy of accelerating burn healing in diabetic rats using low-power visible and invisible lasers. Background Data: Low-level laser therapy (LLLT) has been used in a number of diabetic animal and human studies, with both positive and no effects. MATERIALS AND METHODS: Male Sprague-Dawley rats were used in the study. Streptozotocin (70 mg/kg) was given for diabetes induction. A burn wound was created on the shaved back of the animals using a metal rod heated to 600 degrees C. The study was performed using 532-, 633-, 670-, 810-, and 980-nm diode lasers. Incident doses of 5, 10, 20, and 30 J/cm(2) and a treatment schedule of three times per week were used in the experiments. The burned areas on all rats were measured and plotted on a chart, and the slope values (mm(2)/d) and the percentages of burn healing were compared. RESULTS: The percentage of burn healing on diabetic rats after LLLT was 78.37% for the visible lasers and 50.68% for the invisible lasers. There was a significant difference (p < 0.005) between visible lasers and invisible lasers in the percentage of burn healing on diabetic rats after laser therapy. CONCLUSION: LLLT at the appropriate treatment parameters can accelerate burn healing on diabetic rats using both visible and invisible lasers. The effects of visible lasers were better than those of invisible lasers in accelerating burn healing on diabetic rats in this study.

Photomed Laser Surg. 2008 Feb;26(1):47-54.

Effectiveness of laser photobiomodulation at 660 or 780 nanometers on the repair of third-degree burns in diabetic rats.

Meireles GC, Santos JN, Chagas PO, Moura AP, Pinheiro AL.

Laser Center, School of Dentistry, Department of Propedeutics and Integrated Clinics, Universidade Federal da Bahia, Salvador, Brazil.

OBJECTIVE: The aim of this investigation was to compare by light microscopy the effects of laser photobiomodulation (LPBM) at lambda = 660 nm and lambda = 780 nm on third-degree burns in diabetic Wistar rats. BACKGROUND DATA: Burns are severe injuries that result in fluid loss, tissue destruction, infection, and shock, that may result in death. Diabetes is a disease that reduces the body’s ability to heal properly. LPBM has been suggested as an effective method of improving wound healing. MATERIALS AND METHODS: A third-degree burn measuring 1.5 x 1.5 cm was created in the dorsum of each of 55 animals, and they were divided into three groups that were or were not treated with LPBM (lambda = 660 nm or lambda = 780 nm, 35 mW, varphi = 2 mm, 20 J/cm(2)). The treatments were started immediately post-burn at four points within the burned area (5 J/cm(2)) and were repeated at 24-hour intervals over 21 d. The animals were humanely killed after 3, 5, 7, 14, and 21 d by an overdose of intraperitoneal general anesthetic. The specimens were routinely cut and stained and analyzed by light microscopy. RESULTS: We found that healing in the animals receiving 660-nm laser energy was more apparent at early stages, with positive effects on inflammation, the amount and quality of granulation tissue, fibroblast proliferation, and on collagen deposition and organization. Epithelialization and local microcirculation were also positively affected by the treatment. CONCLUSION: The use of 780-nm laser energy was not as effective as 660-nm energy, but it had positive effects at early stages on the onset and development of inflammation. At the end of the experimental period the primary effect seen was on the amount and quality of the granulation tissue. The 660-nm laser at 20 J/cm(2), when used on a daily basis, was more effective than the 780-nm laser for improving the healing of third-degree burns in the diabetic rats beginning at the early stages post-burn.

Photomed Laser Surg. 2007 Dec;25(6):519-25.

Effect of low-level laser therapy on skin fibroblasts of streptozotocin-diabetic rats.

Mirzaei M, Bayat M, Mosafa N, Mohsenifar Z, Piryaei A, Farokhi B, Rezaei F, Sadeghi Y, Rakhshan M.

Avicenna Hospital, Mazandran Medical University, Sari, Iran.

OBJECTIVE: This study explored the effects of low-level laser therapy (LLLT) on cellular changes in cell culture and organ culture of skin from streptozotocin-diabetic (STZ-D) rats. BACKGROUND DATA: Growth of skin and its fibroblasts are impaired in diabetes. Therefore the healing of skin wounds is impaired in diabetic patients. The positive effects of LLLT on complications of diabetes in patients and animal models have been shown. METHODS: Diabetes was induced in rats by streptozotocin 30 days after its injection. Two sets of skin samples were extracted from skin under sterile conditions. Fibroblasts that were extruded from the samples were proliferated in vitro, and another set of samples were cultured as organ culture. A 24-well culture medium containing Dulbecco’s modified minimum essential medium was supplemented by 12% fetal bovine serum. There were five laser-treated and five sham-exposed groups. A helium-neon laser was used, and 0.9-4 J/cm(2) energy densities were applied four times to each organ culture and cell culture. The organ cultures were analyzed by light microscopy and transmission electron microscopy examinations. Cell proliferation was evaluated by dimethylthiazol-diphenyltetrazolium bromide (MTT) assay. RESULTS: Statistical analysis revealed that 4-J/cm(2) irradiation significantly increases the fibroblast numbers compared to the sham-exposed cultures (p = 0.046). CONCLUSION: It is concluded that LLLT resulted in a significant increase of fibroblast proliferation of STZ-D rats in vitro.

Rozhl Chir. 2007 Jul;86(7):384-7.

[The influence of laser irradiation with different power densities on incisional wound healing in healthy and diabetic rats]

[Article in Slovak]

Kilík R, Bober J, Gál P, Vidinský B, Mokrý M, Longauer F, Sabo J.

1. Chirurgická klinika, Lekárska fakulta, Univerzity Pavla Jozefa Safárika v Kosiciach, Slovenská republika,

INTRODUCTION: The optimal parameters of low level laser therapy (LLLT) are still under debate. It has been documented that a dose or 5 J/cm2 would be capable to accelerate the wound healing process in patients. However, the optimal delivering form, i.e. power intensity, is unknown. Therefore, the aim of our study was to compare different power densities of LLLT. MATERIALS AND METHODS: Sixteen male Sprague-Dawley rats were included in this experiment and randomized into two groups, normal healthy group and streptozotocine induced diabetic group. In general anesthesia four full thickness skin incisions were performed under standard aseptic conditions on the back of each rat and immediately closed using intradermal running suture. Three wounds were stimulated with diode laser (wavelength: 635 nm; daily dose 5 J/cm2; power densities: 1 mW/cm2, 5 mW/cm2 and 15 mW/cm2) each with different power density while the fourth wound served as control. Six days after surgery animals were sacrificed and samples removed for histological evaluation. RESULTS: Our study demonstrated that LLLT positively influences wound healing. The most significant changes were observed in wounds stimulated at the highest power density 15 mW/cm2. Since using the highest power density the shortest time is needed to achieve the optimal daily dose of 5 J/cm2, it can be suggested that 15 mW/cm2 might be optimal parameter for such a therapy in patients.

Photomed Laser Surg. 2007 Apr;25(2):72-7.

Low-level laser therapy enhances wound healing in diabetic rats: a comparison of different lasers.

Al-Watban FA, Zhang XY, Andres BL.

Laser Research Section, Biological and Medical Research Department, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia. watban@kfshrc.edu.sa

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.

Photomed Laser Surg. 2006 Aug;24(4):474-9.

Comparison between wound healing in induced diabetic and nondiabetic rats after low-level laser therapy.

Rabelo SB, Villaverde AB, Nicolau R, Salgado MC, Melo Mda S, Pacheco MT.

Instituto de Pesquisa e Desenvolvimento (IP&D), Universidade do Vale do Paraiba (UNIVAP), São José dos Campos, São Paulo, Brazil.

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.

Acta Cir Bras. 2006 May-Jun;21(3):177-83. Epub 2006 May 26.

Analysis of the influence of low-power HeNe laser on the healing of skin wounds in diabetic and non-diabetic rats.

Carvalho PT, Mazzer N, dos Reis FA, Belchior AC, Silva IS.

Department of Physiotherapy, University for State and Pantanal Region Development, Campo Grande, MS, Brazil. ptpaulo@terra.com.br

PURPOSE: To study the influence of HeNe laser irradiation on the collagen percentage in surgically-induced skin wounds in rats with and without alloxan-induced diabetes, by morphometric analysis of collagen fibers. METHODS: 48 male Wistar rats were used, divided into groups: laser-treated diabetic (group 1); untreated diabetic (group 2); treated non-diabetic (group 3); and untreated non-diabetic (group 4). For groups 1 and 2, diabetes was induced by intravenous injection of alloxan (2,4,5,6-tetraoxypyrimidine; 5,6-dioxyuracil; Sigma), into the dorsal vein of the penis, at a rate of 0.1 ml of solution per 100 g of body weight. A wound was made on the back of all the animals. Groups 1 and 3 were treated with HeNe laser (4 J/cm2) for 60 s. One animal from each group was sacrificed on the 3rd, 7th and 14th days after wounding. Samples were taken, embedded in paraffin, stained with hematoxylin-eosin and Masson’s trichrome, and morphometrically analyzed using the Imagelab software. The percentages of collagen fibers were determined from the samples from the euthanasia animals. The data were treated statistically using analysis of variance (ANOVA) and the Student t and Kruskal-Wallis tests. The significance level was set at 0.05 or 5%. RESULTS: The results obtained from the samples taken on the third, seventh and fourteenth days after wounding demonstrated that the laser-treated group presented a statistically significant (p<0.05) greater mean quantity of collagen fibers than in the non-treated group, both for diabetic rats (p = 0.0104) and for non-diabetic rats (p = 0.039). CONCLUSION: The low-power laser (632.8 nm) was shown to be capable of influencing the collagen percentage in skin wounds by increasing the mean quantity of collagen fibers, both for the diabetic and for the non-diabetic group.

Photomed Laser Surg. 2005 Apr;23(2):187-90.

Effect of low intensity helium-neon (He-Ne) laser irradiation on diabetic wound healing dynamics.

Maiya GA, Kumar P, Rao L.

Department of Physiotherapy, MAHE University, Manipal, India. ajmaiya@yahoo.com

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.

Photomed Laser Surg. 2004 Aug;22(4):281-90.

Photobiomodulation improves cutaneous wound healing in an animal model of type II diabetes.

Byrnes KR, Barna L, Chenault VM, Waynant RW, Ilev IK, Longo L, Miracco C, Johnson B, Anders JJ.

Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA. krb27@georgetown.edu

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.

J Clin Laser Med Surg. 2003 Oct;21(5):249-58.

Polychromatic LED therapy in burn healing of non-diabetic and diabetic rats.

Al-Watban FA, Andres BL.

Laser Medicine Research Section, Biological and Medical Research Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia. Watban@KFSHRC.EDU.SA

OBJECTIVE: We determined the effect of polychromatic light-emitting diodes (LED) in burn healing of non-diabetic and streptozotocin-induced diabetic rats. BACKGROUND DATA: LEDs were used as the light source for phototherapy. MATERIALS AND METHODS: The polychromatic LED is a cluster of 25 diodes emitting photons at wavelengths of 510-543, 594-599, 626-639, 640-670, and 842-879 nm with 272-mW output power. Age-matched, male Sprague-Dawley rats (n = 30) were used. Streptozotocin (70 mg/kg) was used for diabetes induction. Rat weight, hyperglycemia, and glycosuria were monitored for the first 3 days and weekly thereafter. Rats were anesthetized and shaved after 1 week of diabetes. Burn areas of 1.5 +/-.03 cm2 were created using a metal rod pre-heated up to 600 degrees C that was applied for 2 sec. Diabetic and non-diabetic rats were randomized into the following treatment groups: control, 5, 10, 20, and 30 J/cm2. Light treatment commenced after burn infliction and was repeated three times per week. Burn areas were measured daily. RESULTS: Burn healing was impaired significantly during diabetes by -46.17%. Polychromatic LED treatment using 5, 10, 20, and 30 J/cm2 incident doses influenced healing by 6.85%, 4.93%, -4.18%, and -5.42% in the non-diabetic rats; and 73.87%, 76.77%, 60.92%, and 48.77% in the diabetic rats, relative to their controls, respectively. CONCLUSION: The effect of polychromatic LED in non-diabetic rats was insignificant; however, it simulated the trend of stimulation and inhibition seen using low-level lasers. Significant stimulation observed in the diabetic rats demonstrated the usefulness of polychromatic LED in diabetic burn healing.

J Clin Laser Med Surg. 2001 Dec;19(6):305-14.

Effect of NASA light-emitting diode irradiation on wound healing.

Whelan HT, Smits RL Jr, Buchman EV, Whelan NT, Turner SG, Margolis DA, Cevenini V, Stinson H, Ignatius R, Martin T, Cwiklinski J, Philippi AF, Graf WR, Hodgson B, Gould L, Kane M, Chen G, Caviness J.

Department of Neurology, Medical College of Wisconsin, Milwaukee 53226, USA.

OBJECTIVE: The purpose of this study was to assess the effects of hyperbaric oxygen (HBO) and near-infrared light therapy on wound healing. BACKGROUND DATA: Light-emitting diodes (LED), originally developed for NASA plant growth experiments in space show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper, we review and present our new data of LED treatment on cells grown in culture, on ischemic and diabetic wounds in rat models, and on acute and chronic wounds in humans. MATERIALS AND METHODS: In vitro and in vivo (animal and human) studies utilized a variety of LED wavelength, power intensity, and energy density parameters to begin to identify conditions for each biological tissue that are optimal for biostimulation. Results: LED produced in vitro increases of cell growth of 140-200% in mouse-derived fibroblasts, rat-derived osteoblasts, and rat-derived skeletal muscle cells, and increases in growth of 155-171% of normal human epithelial cells. Wound size decreased up to 36% in conjunction with HBO in ischemic rat models. LED produced improvement of greater than 40% in musculoskeletal training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis. CONCLUSION: We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program.

Lasers Surg Med. 1997;20(1):56-63.

Effects of photostimulation on wound healing in diabetic mice.

Yu W, Naim JO, Lanzafame RJ.

Laser Surgical Research Laboratory, Rochester General Hospital, New York 14621, USA.

Comment in:

  • Lasers Surg Med. 2001;29(2):105-6.

BACKGROUND AND OBJECTIVE: Low-level laser irradiation at certain fluences and wavelengths can enhance the release of growth factors from fibroblasts and stimulate cell proliferation in vitro. We evaluated whether low-level laser irradiation can improve wound healing in diabetes mellitus. STUDY DESIGN/MATERIALS AND METHODS: Genetically diabetic mice (C57BL/Ksj/db/db) were used as the animal model for this wound healing study. The experimental animals were divided among four groups: negative control, positive control (topical basic fibroblast growth factor [bFGF] on wound), laser therapy group; and a combination group of laser therapy and topical bFGF. An argon dye laser (Lexel Auora Model 600) at a wavelength of 630 nm and an output of 20 m W/cm2 was used as the light source. The speed of wound closure and histological evaluation were used to analyze the experimental results. RESULTS: Laser irradiation enhanced the percentage of wound closure over time as compared to the negative control group (58.4 +/- 2.6 vs. 40.8 +/- 3.4 at day 10 and 95.7 +/- 2 vs. 82.3 +/- 3.6 at day 20, P < .01). Histological evaluation showed that laser irradiation improved wound epithelialization, cellular content, granulation tissue formation, and collagen deposition in laser-treated wounds as compared to the negative control group (6.4 +/- 0.16 vs. 3.8 +/- 0.13 at day 10 and 12 +/- 0.21 vs. 8.2 +/- 0.31, P < .01). CONCLUSION: This study of laser biostimulation on wound healing in diabetic mice suggests that such therapy may be of great benefit in the treatment of chronic wounds that occur as a complication of diabetes mellitus.