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

Background and Objective: The use of low-intensity laser therapy (LILT) as a therapeutic modality has become popular in a variety of clinical applicat ions including the promotion of wound repair. Although the clinical evidenc e base for such application remains sparse, recent studies have demonstrate d a number of quantifiable photobiological effects associated with such the rapy. In the present study, the effect of laser irradiation at various radi ant exposures on a radiation-impaired wound-healing model in murine skin wa s investigated. Study Design/Materials and Methods: The study included two phases; in phase one, male Balb/c mice (n = 36; age-matched at 10 weeks) were randomly allocated to three experimental groups (n = 12, each group). In all groups, a well-de fined area on the dorsum was exposed to 20 Gy x-rays. Seventy-two hours pos tirradiation, all mice were anaesthetised and a 7 x 7 mm area wound was mad e on the dorsum. All wounds were videotaped alongside a marker scale (three times weekly) until closure was complete. In groups 2 and 3, mice were tre ated with laser irradiation (0.5 and 1.5 J/cm(2), respectively) three times weekly by using a 660-nm GaAlAs laser unit (5 kHz; 15 mW; Omega Laser Syst ems, London, UK). Wound areas were then calculated by using an image analys is system (Fenestra 2.1), and results were analyzed by using repeated measu res and one-factor analysis of variance statistical tests. In phase two, tw o experimental groups were included (n = 12 each group); the protocol was i dentical to that described for phase 1; however, mice in group 2 were treat ed with a radiant exposure of 4 J/cm(2) Results: Results from this investigation demonstrated that treatment with 0 .5, 1.5. and 4 J/cm2 had no beneficial effect on the rate of wound closure (P > 0.05). Conclusion: These findings provide little evidence of the putative stimulat ory effects of LILT in vivo at the parameters investigated. (C) 2000 Wiley- Liss, Inc.