Laser photostimulation (660 nm) of wound healing in diabetic mice is not brought about by ameliorating diabetes

Abstract

We have used a 660-nm 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). It is possible that the stimulation of healing could be due to possible diabetes-modifying properties of laser light. This has been examined by using the 660 nm laser to irradiate non-wounded diabetic mice with the same dose and at same location as for wounded diabetic mice. Twenty-two diabetic mice were used and divided into two equal groups. Body weight and water intake of mice were measured daily for 7 days prior to the start of treatment (Day 0). The left flank of mice in the experimental group was irradiated with 660 nm laser, 100 mW, 20 seconds/day, 7 days; for mice in the control group, the left flank was sham-treated with the laser power supply not switched on. Body weight and water intake of mice were measured to Day 14. On Day 14, the mice were fasted for 4 hours, anaesthetized with sodium pentobarbitone (i.p.) and blood collected by cardiac puncture into heparinized tubes. The plasma was assayed for glucose and glycated hemoglobin A1c. There were no significant differences in body weight and water intake over 22 days between mice in the experimental group and control group. On day 14, the mean blood plasma glucose level was not significantly different between the two groups; glycated hemoglobin A1c was not detected in the samples. Irradiation of the left flank in diabetic mice with 660 nm laser system does not have a significant hypoglycemic effect, and the laser-stimulated healing of wounds in diabetic mice is due to cellular and biochemical changes in the immediate wound environment.