Low-intensity laser irradiation at 660nm stimulates cytochrome c oxidase in stressed fibroblast cells

Background and Objective Low-intensity laser irradiation (LILI) has been used to modulate a variety of biological processes, including diabetic wound healing. The mechanism of action is thought to exist primarily with the mitochondria. This study aimed to determine the effect of irradiation on normal, diabetic, and ischemic mitochondrial electron transport chain (ETC) complexes. Materials and Methods Normal, diabetic and ischemic human skin fibroblast mitochondria were irradiated in vitro at a wavelength of 660?nm and a fluence of either 5 or 15?J/cm2. Non-irradiated mitochondria served as controls. Enzyme activities of mitochondrial complexes I, II, III, and IV were determined immediately post-irradiation. Normal, diabetic, and ischemic cells were irradiated and adenosine triphosphate (ATP) and active mitochondria were determined by luminescence and fluorescent microscopy, respectively. Results Irradiated diabetic mitochondria at a fluence of 15?J/cm2 showed a significant decrease in complex III activity (P?<?0.05). Normal (P?<?0.01) and diabetic (P?<?0.05) mitochondria irradiated at either 5 or 15?J/cm2 showed a significant increase in complex IV activity. ATP results showed a significant increase in irradiated normal cells (5?J/cm2; P?<?0.05) and diabetic cells (15?J/cm2; P?<?0.01). There was a higher accumulation of active mitochondria in irradiated cells than non-irradiated cells. Conclusion Irradiation at 660?nm has the ability to influence mitochondrial enzyme activity, in particular cytochrome c oxidase. This leads to increased mitochondrial activity and ATP synthesis. Lasers Surg. Med. 44: 429434, 2012. (c) 2012 Wiley Periodicals, Inc.