NOA & Photobiology Conference: Advances in Low Level Light Therapy for Wound Healing

1. 2nd INTERNATIONAL CONFERENCE ON NEARFIELD OPTICAL ANALYSIS (NOA) & PHOTOBIOLOGY May 31 - June 1, 2001 NASA-Johnson Space Center, Houston, Texas Co- sponsored by DARPA, NASA-JSC, Medical College of Wisconsin

2. - Several areas of the Low Level Light Therapy [LLLT], respectively Low Intensity Light Activated Biostimulation [LILAB], were discussed in relation to the fundamental photobiological processes that are affected by light and the cellular mechanisms that contribute to the potential use for stimulation of the wound healing process. - The evolution of NASA developed LED light sources in the 600 - 1100 nm range of wavelengths demonstrates that for various clinical applications, expensive, bulky lasers are not required. - There was a general consensus that several areas of research need to be pursued in order to establish the foundation for a more wide-spread use of the LLLT/LILAB. - There was alsoa general agreement that researchers need to establish several model systems as reference standards for future work in cellular, molecular, and biophysical systems that have already been investigated. - Five research areas were identified as focal points for the next generation of research studies: 1. Biophysics of the absorbing molecules and potential design of photosentizers. 2. Cellular mechanisms of photobiostimulation of the wound healing process. 3. Issues of clinical applications using LLLT/LILAB to stimulate wound healing in several major body tissues. 4. LLLT/LILAB potential for local bacteristatic action [probably as an indirect immune system enhancing effect rather than actual sterilization]. 5. Combined effects of LLLT/LILAB + photosentizers or adjuvant therapy to enhance the wound healing processes.

3. Biophysics of the absorbing molecules and potential design of photosentizers • Major Research Questions • Absorption Spectral of: • Cytochrome oxidase • Other Mitochondrial molecules • Rhodopsin • Photophrin rings (hemoglobin derivatives and Myoglobin) • Mechanisms of therapeutic effects on • Acceleration of normal skin & epithelial wound closure • Chronic diabetic wounds • Radiation induced ulcers • Neuron regeneration • Bone regeneration - skeletal and different areas of the maxilla (replacement teeth) • Potential stimulation of neovascularization • Dental pulp regeneration - waveguide structure of dentin focusing the NIR light parallel to the dentin channels on the pulp • Biofilm repellant potential of light • Strategies for design of new photosensitizers • Testing photosensitizers using tissue culture models

4. Cellular mechanisms of LILAB on the wound healing process • Questions • Effects on inflammatory secretions • PGE2, already documented • Leukotriene 4, other prostaglandins & inflammatory mediators • Cytokines - specific meachanisms in various stages of the tissue regeneration process • Effects on inflammatory cells and cellular immune responses • Polymorphonuclear leukocytes - initial invasion after wounding • Antigen presentation - dendritic cells • Macrophage functions and Antigen recognition - T & B lymphocytes • Comparison of effects of LLLT/LILAB vs. steroids • Effects on wound repair sequece • Collagen & Matrix formation • DNA synthesis - normally maximum at 96 hours after wounding • Specific mRNAs for key protein expression • Individual cell (type) regeneration • Neural cells - neurite regeneration following nerve transection or radiation [high energy laser damage] • Effects of LILAB on cell reaction and cell functionality / NOA • Online mapping of cellular functions on the nanoscale level

5. Issues of clinical applications using LLLT/LILAB to stimulate wound healing • Questions • Standardization of Exposures - for therapeutic models and comparison of clinical results • Standard reference to locally administered Energy Density /Total Dose [at various Intensities and wavelengths] • Exposure areas and time - area of irradiation field of each exposure & number of exposures • Depth of penetrationto the target volume vs. wavelength of effect • Homogeneity of irradiation field (simultaneous stimulation of a large number of photoreceptors) • Therapy- optimization • Bone regeneration - long time course [when is therapy timeline optimum for maximum long term benefits] • Skin - cuts, shrapnel, burns [fire, chemical, radiation] • Dental - reconstructive surgery vs. outpatient dental treatments • Deep tissue - (diabetic chronic wounds) • Time course of effect • Daily LLLT/LILAB application - in the majority of cases successful • Every three days irradiation - appears adequate for many superficial wounds • Total Duration of treatment - different for various tissues and depth [bone, skin, muscle, nerves] • Potential reduction of pain • Dental hypersensitivity - already demonstrated • Acute pain vs. Reduction of pain medication • Use of photosenstizers

6. Combined effects of LLLT/LILAB + photosentizers or adjuvant therapy to enhance the wound healing process • Questions • Combined Field Effects • Effective penetration depth in different tissues [at different wavelengths] • NIR light - lasers [monochromatic, polarized, coherent] vs. LEDs • NIR light + Electric or magentic fields • Optimum sequence of exposure to individual or combined wavelengths • Effects of combined wavelengths [LEDs at 630, 720, 880 nm] • Different wavelength in an optimized temporal and/or spatialapplication sequence • Duration of treatment

7. Potential Photodynamic effects on Microbes [in situ sterilization] • Questions • Specific threshold for reducing local bacterial levels • Oral • Trauma - open wounds • Direct effects vs. local immuno-stimulation [indirect effects] • Potential of LLLT/LILAB as adjuvant for inhibition of fungal infections [spores] • Possible use for soldiers or workers in tropical & rainforest environments • Potential effects on growth of Nanobacteria • Long term tissue culture testing - models are required