Laser photostimulation accelerates wound healing in diabetic rats

In this study, we examined the hypothesis that laser photostimulation can f acilitate healing of unpaired wounds in experimental diabetes using a rat m odel. Diabetes was induced in male rats by streptozotocin injection and two 6 mm diameter circular wounds were created on either side of the spine. Th e left wound of each animal was treated with a 632.8nm He:Ne laser at a dos e of 1.0J/cm(2) for five days a week until the wounds closed (three weeks). Measurements of the biomechanical properties of the laser-treated wounds i ndicated there was a marginal increase in maximum load (16%), stress (16%), strain (27%), energy absorption (47%) and toughness (84%) compared to cont rol wounds of diabetic rats. Biochemical assays revealed that the amount of total collagen was significantly increased in laser treated wounds (274 +/ -8.7 mug) over the control wounds (230 +/-8.4 mug). Sequential extractions of collagen from healing wounds showed that laser treated wounds had signif icantly greater concentrations of neutral salt soluble (15%) and insoluble collagen (16%) than control wounds, suggesting accelerated collagen product ion in laser treated wounds. There was an appreciable decrease in pepsin so luble collagen (19%) in laser treated wounds over control wounds, indicatin g higher resistance to proteolytic digestion. In conclusion, the biomechani cal and biochemical results collectively suggest that laser photostimulatio n promotes the tissue repair process by accelerating collagen production an d promoting overall connective tissue stability in heating wounds of diabet ic rats.