Direct stimulatory effect of low-intensity 670 nm laser irradiation on human endothelial cell proliferation.

BACKGROUND: Endothelial cell (EC) proliferation plays a key role in the process of tissue repair. Low-intensity laser irradiation has been demonstrated to accelerate wound healing and to improve microvascularization. OBJECTIVES: The present study evaluated a possible stimulatory influence of low-intensity laser irradiation on human umbilical vein endothelial cell (HUVEC) proliferation in a systematic manner. METHODS: Subconfluent cultures of HUVEC were irradiated every other day with a 670-nm diode laser (intensity: 10-65 mW cm(-2), dose: 2-8 J cm(-2)) during a period of 6 days. Cell proliferation was evaluated quantitatively by counting in a haemocytometer. RESULTS: Our data demonstrate a dose-dependent and intensity-dependent stimulatory effect of laser irradiation on HUVEC cell proliferation. Doses of between 2 and 8 J cm(-2) induced statistically significant cell proliferation. Testing different intensities at a constant dose of 8 J cm(-2), 20 and 65 mW cm(-2) induced most pronounced cell proliferation. CONCLUSIONS: Low-intensity laser irradiation influences EC proliferation and might thereby contribute to the increase in angiogenesis and the acceleration of wound healing in vivo.

Low-intensity laser therapy: a review.

Low-intensity laser radiation is characterized by its ability to induce athermic, nondestructive photobiological processes. Although it has been in use for more than 30 years, this phototherapy is still not an established therapeutic modality. We have summarized the main arguments being brought up against the use of this therapy and have reviewed the literature addressing both its in vitro and in vivo effects. We conclude that low-intensity laser irradiations might be of benefit in selected indications if the existing preliminary data can be confirmed by more prospective and well-controlled studies.

Low intensity laser irradiation in the treatment of recalcitrant radiation ulcers in patients with breast cancer--long-term results of 3 cases.

Radiotherapy can be followed by recalcitrant skin ulcers. As low intensity laser irradiation has been demonstrated to have a beneficial effect on impaired wound healing, we investigated its efficacy and safety in three patients with chronic radiation ulcers. The three patients, previously mastectomized due to breast cancer, with recalcitrant radiation ulcers of the skin were treated with a 30 mW helium-neon laser (wavelength: 632.8 nm, intensity: 3 mW/cm2, dose: 30 J/ cm2) three times weekly. In all patients, complete wound closure was achieved within a period of 7, 5, and 8 weeks. One patient died 6 weeks after laser treatment due to tumor cachexia. Neither of the other patients showed recurrence of radiation ulcers or neoplasm during a follow-up of 36 months. Low intensity helium-neon laser irradiation has been shown to be effective in the induction of wound healing in radiotherapy-induced ulcers in three patients with breast cancer.

Diabetic neuropathic foot ulcer: successful treatment by low-intensity laser therapy.

OBJECTIVE: To evaluate the efficacy of low-intensity laser irradiation for the induction of wound healing of a diabetic neuropathic foot ulcer. CASE: We report a case of a man with insulin-dependent diabetes mellitus, sensory neuropathy, macroangiopathy and microangiopathy who had been suffering from an ulcer of his first left toe accompanied by osteomyelitis for 6 weeks. RESULTS: After a total of 16 sessions of low-intensity laser therapy using a 670-nm diode laser administered within a 4-week period the ulcer healed completely. During a follow-up period of 9 months, there was no recurrence of the ulcer even though the patient's metabolic condition remained unstable. CONCLUSIONS: Although laser therapy was not applied as a monotherapy, the present observation suggests that it might constitute a useful side-effect-free alternative treatment modality for the induction of wound healing of neuropathic ulcers in diabetic patients. Therefore large properly controlled randomized studies seem justified.

Role of ground and excited singlet state oxygen in the red light-induced stimulation of Escherichia coli cell growth.

Irradiation of selected Escherichia coli defective strains with red-light induces a stimulation of the cell growth rate. Such effect is wavelength-dependent and is accompanied by a transient increase of the cell volume and some enzymic activities. The presence of oxygen appears to be essential for the occurrence of a significant photostimulatory effect. The results obtained upon irradiation in the presence of quenchers (tryptophan, histidine, azide) or enhancers (deuterium oxide) of singlet oxygen (1O2) strongly suggest that this activated oxygen derivative is generated by excitation of endocellular chromophores (possibly cytochromes). The reaction of 1O2 with nearby cellular targets could induce a sublethal cell damage which in turn promotes an accelerated cell metabolism.

Increased dermal angiogenesis after low-intensity laser therapy for a chronic radiation ulcer determined by a video measuring system.

Acute and chronic radiation-induced dermatitis can occur after high doses of ionizing radiation of the skin. We describe a patient with a long-lasting radiotherapy-induced ulcer that healed after low-intensity laser therapy. A video measuring system was used to determine the number of dermal vessels in the ulcer before and after laser treatment. We found a statistically significant increase in the number of dermal vessels after low-intensity laser therapy in both the central and marginal parts of the ulcer compared with its pretreatment status.

Induction of complete wound healing in recalcitrant ulcers by low-intensity laser irradiation depends on ulcer cause and size.

Chronic skin ulcers still represent a therapeutic challenge in dermatology. Among the various non-invasive treatment modalities used for the improvement of impaired wound healing, low-intensity laser irradiations are gaining an increasing body of interest. We used low-intensity laser irradiations delivered by a 30 mW helium-neon laser at an energy density of 30 J/cm2 three times weekly for the induction of wound healing in ulcers of diverse causes. Twenty patients with the same number of ulcers, which had previously been treated by conventional wound care for a median period of 34 weeks (range: 3-120 weeks) without any significant evidence of healing, were included in the study. Concerning the underlying disorders, patients were divided into four groups: diabetes, arterial insufficiency, radio damage and autoimmune vasculitis. In all ulcers, complete epithelization could be induced by laser therapy. No amputation or any other surgical intervention was necessary and no adverse effects of any kind were noted during low-intensity laser treatment. Regarding the different diagnoses, a statistically significant difference was noted (P = 0.008): ulcers due to radio damage healed significantly faster than those caused by diabetes (6 weeks [range: 3-10 weeks] vs. 16 weeks [range: 9-45 weeks], P = 0.005). Wound healing in autoimmune vasculitis (24 weeks [range: 20-35 weeks]) required longer than in radiodermitis, although the difference was not significant. In addition to the diagnosis, wound size was found to be an important factor influencing the duration of wound closure (P = 0.028), whereas duration of previous conventional treatment (P = 0.24) and depth (P = 0.14) showed no effect. Our results indicate that low-intensity laser irradiation could be a valuable non-invasive tool for the induction of wound healing in recalcitrant ulcers, and that healing time is correlated with the ulcer cause and size.

Low-intensity laser irradiation improves skin circulation in patients with diabetic microangiopathy.

OBJECTIVE: Diabetic foot problems due to angiopathy and neuropathy account for 50% of all nontraumatic amputations and constitute a significant economic burden to society. Low-intensity laser irradiation has been shown to induce wound healing in conditions of reduced microcirculation. We investigated the influence of low-intensity laser irradiation by means of infrared thermography on skin blood circulation in diabetic patients with diabetic microangiopathy. RESEARCH DESIGN AND METHODS: Thirty consecutive patients with diabetic ulcers or gangrenes and elevated levels of glycosylated hemoglobin were randomized by blocks of two to receive either a single low-intensity laser irradiation with an energy density of 30 J/cm2 or a sham irradiation over both forefoot regions in a double-blind placebo-controlled clinical study. Skin blood circulation as indicated by temperature recordings over the forefoot region was detected by infrared thermography. RESULTS: After a single transcutaneous low-intensity laser irradiation, a statistically significant rise in skin temperature was noted (P < 0.001 by ANOVA for repeated measurements), whereas in the sham-irradiated control group, a slight but significant drop in temperature (P < 0.001) was found. Subsequently performed contrasts for comparison of measurements before and after irradiation revealed significant temperature increases at 20 min of irradiation time (P < 0.001), at the end of the irradiation (P < 0.001), and 15 min after stopping the irradiation (P < 0.001). In the sham-irradiated feet, the drop in local skin temperature was not significant at 20 min (P = 0.1), but reached significance at the end of the sham-irradiation procedure (P < 0.001) and 15 min after the end of sham irradiation (P < 0.001). CONCLUSIONS: The data from this first randomized double-blind placebo-controlled clinical trial demonstrate an increase in skin microcirculation due to athermic laser irradiation in patients with diabetic microangiopathy.

Healing of Bone Affections and Gangrene with Low-Intensity Laser Irradiation in Diabetic Patients Suffering from Foot Infections.

OBJECTIVE: Evalution of low-intensity laser irradiation on the healing of bone affections and gangrene in patients suffering from diabetic microangiopathy. DESIGN: Case-report study. PATIENTS: Two consecutive diabetic male patients with gangrene, osteomyelitis, and bone fractures. INTERVENTION: Helium-neon laser irradiation (36 J/cm2 ) 50 min/day. MAIN OUTCOME PARAMETER: Healing of gangrene and corticalis lesion as well as remineralisation of bone affections. RESULTS: Within a mean period of 14 weeks not only a complete healing of the diabetic gangrenes but also a radiographically determined reestablishment of corticalis and remineralisation of preexisting bone affections could be achieved. CONCLUSION: We therefore conclude that low-intensity laser irradiation should be further tested as an additional beneficial therapeutic modality for the healing of gangrene and bone affections in diabetic patients.

Effects of low power laser-irradiation on differential blood count and body temperature in endotoxin-preimmunized rabbits.

Low power laser irradiation has been shown to have various immune-modulatory effects under in vitro conditions but little is known about such effects in animal models. Escherichia coli endotoxin-preimmunized rabbits were used to determine the influence of transcutaneously applied low power laser light on differential blood count and rectal temperature. After three initial immunizations animals were either boostered with 5 ng/kg of endotoxin or injected with pyrogen-free saline and subsequently underwent irradiation using two different wavelengths of red laser light and sham irradiation, respectively. Differential blood count of laser-treated animals was characterized by significantly higher lymphocyte values and lower neutrophil values at twenty hours (boostered rabbits) and twenty-three hours (non-boostered rabbits) after irradiation. Differential blood cell counts returned to baseline values within 23 hours in the boostered animals, whereas in the non-boostered rabbits lymphocytes showed a trend to further increase. Recording of rectal temperature revealed a further rise after laser application, changes being of greater magnitude and longer duration in the non-boostered animals. These results seem to indicate that a single low power laser irradiation can modulate immune-responses depending on the immunological status of the organism.