Abstract
Background: Laser irradiation of wounds in mice and rats was shown in previous studies to stimulate healing but in almost all the studies the wounds were not covered.
Purpose: To compare the healing of covered wounds in diabetic and nondiabetic mice and the effect of laser irradiation 660nm at two different fluences (energy densities).
Method: A single wound 5-mm diameter was made on the left flank of forty-seven diabetic and twenty nondiabetic mice and covered with Tegaderm HP dressing (day 1). Wounds were irradiated 660nm 20s using a low power (18mW) or high power (80mW) laser starting immediately post-wounding for 7 consecutive days, with non-irradiated wounds as controls. Mice were euthanized on day 8, 10 or 14. Wound specimens were cut and stained with haematoxylin and eosin, and examined by light microscopy.
Results: Wound healing was impaired in diabetic mice. Tegaderm HP dressing had retarded contraction in a large proportion of diabetic mice (splinted the wounds) and to a lesser extent in nondiabetic mice. Healing of splinted wounds was delayed compared to unsplinted wounds, but laser irradiation at high power stimulated healing by re-epithelization and granulation tissue formation. The fluence of low power laser was estimated to be about 1 J/cm(2), while that of the high power laser was 3.7 to 5.0 J/cm(2).
Conclusion: Laser irradiation of wounds 660nm with 1 J/cm(2) had little effect on healing of wounds in diabetic and nondiabetic mice, whereas irradiation with 3.7 to 5.0 J/cm(2) stimulated healing of wounds in diabetic mice most of which were splinted by the dressing.