Not only plants, but all living things can interact with light. The interaction between biological systems and light quanta is studied by a branch of physics called biophotonics. In this field of study, particular attention is paid to the interaction between the cells of biological tissues and light: thanks to research and clinical experimentation, there is now a large literature supporting the evidence that light stimulates tissue repair and regeneration.
The invention of low-level light therapy
The invention of laser technology in the early 1960s was a breakthrough in the therapeutic use of light, making it possible to study the interaction of individual wavelengths with biological tissues. In 1967 at the Semmelweis Medical University, Hungary, Endre Mester discovered low-power laser light therapy, opening up new horizons for the use of light in medicine. Mester was trying to repeat an experiment conducted by Paul McGuff in Boston, USA, who had successfully used the newly discovered ruby laser to treat malignant tumours in mouse. However, Mester’s customised ruby laser had only a tiny fraction of the power of McGuff’s laser. Although he was unable to cure any tumours with his low-power laser beam, Mester observed an increase in the rate of hair growth and improved wound healing in mice in which he had surgically implanted tumours. This was the first indication that low-level laser light (rather than high power thermal lasers) could have its own beneficial applications in medicine. Thus, the specialized field of phototherapy that utilizes low-dose light for clinical therapy was born. Since then, much has been learned about the mechanism of action of this therapy, including the fundamental fact that the application of light to tissues and organisms can elicit both stimulatory and inhibitory responses, depending on the irradiation parameters used.
Photobiomodulation gaining recognition
With the invention of light-emitting diodes (LEDs), it was no longer necessary to use a monochromatic coherent laser to achieve these beneficial biological effects, as non-coherent LEDs, with parameters comparable with low-power lasers, perform just as well. The use of LEDs, which have a higher safety, user-friendliness and cost-effectiveness profile than lasers, has allowed this type of therapy and its possible beneficial effects to become more widespread. In 2014, the North American Association for Laser Therapy and the World Association for Laser Therapy in a joint conference considered “Photobiomodulation” the term of choice to describe this “form of light therapy that utilizes non-ionizing forms of light sources, including lasers, LEDs, and broadband light, in the visible and infrared spectrum”, suggesting as definition for the term “a nonthermal process involving endogenous chromophores eliciting photophysical and photochemical events at various biological scales. This process results in beneficial therapeutic outcomes including but not limited to the alleviation of pain or inflammation, immunomodulation, and promotion of wound healing and tissue regeneration.”1
Photobiomodulation therefore relies on the absorption of light by target chromophores naturally present in tissues, each with its own light absorption spectrum. Once absorbed, the energy carried by the light beam is used by the tissue to promote chemical reactions or produce conformational changes in certain biomolecules. As with other forms of medication, Photobiomodulation has its active ingredients or “medicine” (irradiation parameters such as: wavelength, irradiance, pulse structure, etc.) and a “dose” (energy density) that it is essential to control in order to reproduce the therapeutic benefit. Thanks to the use of a wide variety of different kinds of light sources (medical devices) and treatment protocols in study design, advances have been made in understanding the mechanisms of action at a molecular, cellular and tissue-based level and an overwhelming number of positive clinical results have been also obtained.
Blue light: a promising therapeutic solution for wound care
Despite the widespread use of medical devices that use wavelengths in the red and infrared range due to their better penetration of skin tissue, blue light (410-430nm) has recently gained attention for its efficacy in promoting the healing of hard-to-heal wounds; this result is due in part to the increased absorption capacity of blue light by cytochrome c oxidase in the mitochondrial respiratory chain, a primary chromophore for Photobiomodulation. In particular, clinical studies have demonstrated the reactivation of healing of wounds of various aetiologies (such as venous ulcers, pressure ulcers, diabetic foot, etc.) that did not respond to conventional therapies, resulting in benefits for patients and cost savings for healthcare organizations. Photobiomodulation has made and continues to make major progress in gaining recognition and we expect further developments for this type of therapy, which is safe, non-invasive and environmentally sustainable as it does not require the use of consumables.
- Anders JJ, Lanzafame RJ, Arany PR. Low-level light/laser therapy versus photobiomodulation therapy. Photomed Laser Surg. 2015 Apr;33(4):183-4. doi: 10.1089/pho.2015.9848.
Figure_ Skin lesion irradiated with blue LED light.
By Lorenzo Targetti, co-founder and CEO of Emoled
Lorenzo Targetti is co-founder and CEO of Emoled, a company operating in the field of optic and photonics applied to life science. He holds a degree in Business at University of Florence and he has 30 years of experience as an entrepreneur, having successfully managed large size international companies in the field of commercial lighting (e.g., Targetti Poulsen Group). In 2007 he won the “Ernst and Young Entrepreneur of the Year” award. His vision and understanding of go to market strategies allowed for the creation of Emoled; he is responsible for the long-term strategy of the company, the preparation and implementation of the business plan, the selection and management of the company’s human resources.
