An Introduction to Low-Level Light Therapy
There have been numerous reports describing the phenomena of low-level light therapy (LLLT) within the clinic and its broad application to alleviate pain, enhance the rate of wound healing, including spinal cord injury, reduce inflammation, improve learning, bolster immunity and combat disease. Yet, despite the breadth of potential applications for which bio-stimulation may prove beneficial, there persists a dramatic ignorance in our understanding of the signal pathways that govern these effects. At the cellular level, there exist a variety of endogenous chromophores such as cytochrome c oxidase, NADPH, FAD, FMN and other factors intrinsic to the electron transport chain in mitochondria that absorb light of specific wavelength and will undoubtedly have their role in bio-stimulation, however the dose dependency of effect with regard to total light fluence and fluence rate, as well as the importance of specific subcellular targeting, remains elusive. Furthermore, the translation of cellular response(s) in vitro to in vivo needs to be expounded. Clearly, a rigorous examination of bio-stimulatory parameters as a function of cellular and tissue response is necessary if we are to attain optimized, reproducible protocolsbasedonatrue scientific rationale for using bio-stimulation as a therapeutic modality in clinic. This paper introduces a number of the challenges we now face for advancing the bio-stimulation phenomena into the scientific mainstream by highlighting our current knowledge in this field as well as some of the research that we are conducting using LLLT in combination with photodynamic therapy.
KeywordsLow-level light therapy photobiomodulation cytochrome c oxidase apoptosis mitochondria laser LED
The authors wish to acknowledge the technical assistance of Anoja Giles with culturing CNS-1 cells and Emily Pai for her work on biodynamic phototherapy. We also wish to thank Canadian Institute of Health Research for financial support.
- 7.Giuliani A, Fernandez M, Farinelli M, Baratto L, Capra R, Rovetta G, Monteforte P, Giardino L, Calza L. “Very low level laser therapy attenuates edema and pain in experimental models.” Int J Tissue React. 26: 29–37 (2004).Google Scholar
- 14.Simunovic Z. “Low level laser therapy with trigger points technique: a clinical study on 243 patients.” J Clin Laser Med Surg. 14: 163–167 (1996).Google Scholar
- 17.Rochkind S, Shahar A, Nevo Z. “An innovative approach to induce regeneration and the repair of spinal cord injury.” Laser Ther. 9: 151 (1997).Google Scholar
- 31.Shefer G, Partridge TA, Heslop L, Gross JG, Oron U, Halevy O. “Low-energy laser irradiation promotes the survival and cell cycle entry of skeletal muscle satellite cells.” J Cell Sci. 115: 1461–1469 (2002).Google Scholar
- 33.Gourley PL, Hendricks JK, McDonald AE, Copeland RG, Barrett KE, Gourley CR, Singh KK, Naviaux RK. “Mitochondrial correlation microscopy and nanolaser spectroscopy — new tools for biophotonic detection of cancer in single cells.” Technol Cancer Res Treat. 4: 585–592 (2005).Google Scholar
- 39.Yang VXD, Gordon ML, Tang SJ, Marcon NE, Gardiner G, Qi B, Bisland S, Seng-Yue E, Lo S, Pekar J, Wilson BC, Vitkin IA. “High speed, wide velocity dynamic range Doppler optical coherence tomography (part III): in vivo endoscopic imaging of blood flow in the rat and human gastrointestinal tract.” Opt Express. 11: 2416–2424 (2003).CrossRefGoogle Scholar
- 40.Larsson M, Nilsson H, Stromberg T. “In vivo determination of local skin optical properties and photon path length by use of spatially resolved diffuse reflectance with applications in laser Doppler flowmetry.” Appl Optics. 42: 124–134.Google Scholar
- 42.Sun H, Mangner TJ, Collins JM, Muzik O, Douglas K, Shields AF. “Imaging DNA synthesis in vivo with 18F-FMAU and PET.” J Nucl Med. 46: 292–296 (2005).Google Scholar
- 44.Czarnota GJ, Kolios MC, Hunt JW, Sherar MD. “Ultrasound imaging of apoptosis. DNA-damage effects visualized.” Methods Mol Biol. 203: 257–277 (2002).Google Scholar
- 48.Bisland SK, Pai E, Wilson BC, “Biodynamic phototherapy: Priming cells for 5-aminolevu-linic acid-mediated photodynamic therapy. ” In preparation. Google Scholar