Effect of low intensity monochromatic light therapy (890 nm) on a radiation-impaired, wound-healing model in murine skin.
OBJECTIVE
The use of low intensity laser and monochromatic light diodes as a therapeutic modality has become popular in a variety of clinical applications, including the promotion of wound repair. Despite this, the clinical evidence base for such application remains sparse; in contrast, recent studies have demonstrated a number of quantifiable photobiological effects associated with such therapy. In the present study, the effect of low intensity monochromatic light irradiation (MLI) at various radiant exposures upon a radiation-impaired wound model in murine skin was investigated.


METHODS
Male Balb/c mice (n = 50; age matched at 10 weeks) were randomly allocated to five experimental groups (n = 10 each group). In Group 1, mice were left untreated; in Groups 2-5, a well-defined area on the dorsum was exposed to 20 Gy X-ray irradiation. At 72 hours postirradiation, all mice were anaesthetised and a 7-mm-square area wound was made on the dorsum. All wounds were videotaped alongside a marker scale until closure was complete. In Groups 3-5, mice were treated with MLI (0.18, 0.54, and 1.45 J/cm2, respectively) three times weekly using a GaAlAs 890 nm multidiode (n = 60) array unit (270 Hz; maximum rated output, 300 mW; Anodyne, Denver, CO). Subsequently, the area of each wound was measured from video using an image analysis system (Fenestra 2.1), and results were analysed using repeated measure and one-factor ANOVA statistical tests.


RESULTS
X-ray irradiation caused a significant delay (P = 0.0122) in healing by day 7. MLI at 0.18 J/cm2 and 0.54 J/cm2 had no effect upon the rate of wound closure. However, a highly significant (P = 0.0001) inhibition occurred following MLI irradiation at 1.45 J/cm2 by day 16.


CONCLUSIONS
These findings provide little evidence of the putative stimulatory effects of monochromatic light irradiation in vivo, but, rather, reveal the potential for an inhibitory effect at higher radiant exposures.
Lowe
A S
AS
Rehabilitation Sciences Research Group, School of Health Sciences, University of Ulster, Jordanstown, Northern Ireland. A.Lowe@ulst.ac.uk
Walker
M D
MD
O'Byrne
M
M
Baxter
G D
GD
Hirst
D G
DG
D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010789:Phototherapy / Q000379:methods* / Q000706:statistics & numerical data; D011855:Radiodermatitis / Q000473:pathology / Q000628:therapy*; D011897:Random Allocation; D012867:Skin / Q000473:pathology / Q000528:radiation effects*; D013997:Time Factors; D014945:Wound Healing / Q000528:radiation effects*