Abstract 8: Modulation of Cytochrome c Oxidase Activity with Specific Infrared Light Wave Lengths: Noninvasive Therapy for Reperfusion Injury

Reperfusion injury plays a major role in multiple pathologies by inducing generation of reactive oxygen species (ROS) at high mitochondrial membrane potentials (ΔΨ m ). Traditional attempts to scavenge ROS have failed, due to inherent difficulties in sub-cellular delivery within the early minutes of reflow. Accordingly, we developed a non-pharmacologic therapy that targets cytochrome c oxidase (CcO) using infrared light (IRL), and discovered 4 specific IRL wavelengths that reversibly reduce the activity of CcO. We propose that these wavelengths will stabilize ΔΨ m during reperfusion and, thus, provide a non-invasive strategy to attenuate cerebral ischemia-reperfusion injury. Methods and Results: In Protocol 1 , we tested this hypothesis in cell culture. All 4 IRL wavelengths that reduce CcO activity: i) decreased mitochondrial respiratory rate (n=5; p m in a switch-like manner (n=3; p in situ (n=5; p Protocol 2 , we evaluated the neuroprotective effect of the 4 candidate wavelengths in the in vivo rat model of global brain ischemia. All possible wavelength combinations were evaluated using a randomized and blinded study design (15 treatments; n = 8-12/group; total n=153,). At 14 days post-reperfusion, untreated controls demonstrated an 88% loss of neurons in the CA1 hippocampus. Strikingly, all 15 IRL combinations were protective, with neuronal loss ranging from only 11% (best treatment) to 58%: all p-values vs control. The neurologic protection in IRL treated rats was accompanied by preservation of neurologic function, as demonstrated by a 40% improvement in spatial learning deficits (n = 10/group, p Protocol 3 ) we developed a prototype capable of delivering the 4 candidate IRL wavelengths to deep structures of the pig brain with no detectable increase in scalp or brain temperature (ΔT Conclusion: Non-invasive reduction of CcO activity with specific IRL wavelengths is profoundly neuroprotective.