“When light of correct colour and intensity is applied to areas of biological tissue stress, the result is to return to the normal functioning of our cells, time dependant on the the acute or chronic nature of the condition.”

Oxidative stress is the underlying trigger for most diseases

In our cells, oxidative stress is accepted as the underlying trigger for most diseases and degenerative conditions. It is also a component in the inflammatory phase of acute and chronic injuries, as well as the ageing process.

However, when light of the correct colour, and intensity is applied to the area of stress, it immediately displaces the mNO from the receptor site CcO resulting in local vasodilation. This also allows oxygen to attach and begin the process of producing ATP. This removes the cause of ROS production, resulting in a reduction of oxidative stress and a return to normal functioning as our cells are programmed to do.

Stressed cells can benefit from light applied to them

Since every cell has hundreds to thousands of mitochondria, the primary receptor site for light, if light can be applied to the stressed ones with the correct colour and dose, those cells can benefit by a reduction in oxidative stress, increase circulation, increased ATP and the ability to begin normalising and healing.

Mechanism of action (technical)

Most of the effects of Photobiomodulation Therapy can be explained by light absorption in the mitochondria. Every cell in the body has lots of mitochondria (hundreds or thousands per cell). Mitochondria make cellular energy (ATP) from oxygen and pyruvate. In stressed or hypoxic (low oxygen) tissues, mitochondria make their own nitric oxide (NO) which competes with oxygen.

The NO binds to Cytochrome c Oxidase (CcO) (the terminal enzyme in the electron transport chain) and displaces oxygen. This displacement of oxygen has two negative effects; Reduced ATP synthesis Increased oxidative stress (leading to inflammation via the inflammatory ‘master switch’ NF-kB) . The effect of Photobiomodulation Therapy on hypoxic/stressed tissues can be described in several stages:

• Primary effects

Absorption by Cytochrome c Oxidase (CcO) absorbs red and near infrared light

The transfer of light energy by this enzyme triggers a series of downstream effects

One of the secondary effects of Photobiomodulation Therapy is that damaged cells return to normal functionality

• Secondary effects

Modulation of ATP, nitric oxide and reactive oxygen species

Changes in ATP, reactive oxygen species and nitric oxide follow light absorption by CcO. These effects are redox state and dose dependent. In hypoxic or otherwise stressed cells it has been shown many times that following Photobiomodulation Therapy, nitric oxide is released, ATP is increased and oxidative stress is reduced.

• Tertiary effects

Downstream intracellular responses (gene transcription, and cellular signalling)

The downstream effects of Photobiomodulation Therapy released nitric oxide, increased ATP and reduced oxidative stress are many. They are context and cell type specific. Either directly or indirectly these biochemical intermediates affect components in the cytosol, cell membrane, and nucleus that control gene transcription and subsequently cell proliferation, migration, necrosis and inflammation.

• Quaternary effects

Extracellular, indirect, distant effects

Tissues that have not absorbed photons can also be affected indirectly via secretions from cells that have absorbed light. Cells in blood and lymph can be activated and they travel significant distances from the session area to have distant (systemic) effects. These can be autocrine, paracrine, and endocrine effects (sometimes known as a ‘bystander’ effects).

Oedema – lymphatic drainage

There is good evidence that Photobiomodulation Therapy also improves lymphatic flow. A systematic review of eight clinical trials of Photobiomodulation Therapy for post mastectomy lymphoedema concludes that, “There is moderate to strong evidence for the effectiveness of Photobiomodulation Therapy for the management of breast cancer related lymphedema”.

A controlled clinical trial on football players with second degree ankle sprains, found a significant reduction in oedema volume for the laser group compared with placebo laser (both groups also had rest, ice, compression and elevation).

Analgesia

Analgesic effects are probably via a different mechanism from the increased ATP/reduced oxidative stress model described above. According to a systematic review of laser analgesia mechanisms, studies have established that 1064 nm wavelengths PBMT can effectively reduce pain, increase and range of motion. The higher power density laser light > 300 mW/cm2, when absorbed by nociceptors, have an inhibitory effect on Aδ and C pain fibres.

This high power density Photobiomodulation Therapy session slows conduction velocity, reduces amplitude of compound action potentials and suppresses neurogenic inflammation.  Laboratory studies show that Photobiomodulation Therapy blocks anterograde transport of ATP-rich mitochondria in dorsal root ganglion neurons.

Myofascial trigger points

The motor end plate is central to the aetiology of trigger points and EMG studies have shown abnormally high electrical activity over trigger points. Electrical activity is reduced after Photobiomodulation Therapy and clinical studies have shown that Photobiomodulation Therapy has immediate and cumulative effects on reducing pain, however the mechanism of action is not yet fully understood.

Protection against Parkinson’s and other neurodegenerative disorders with low-dose methylene blue and near-infrared light

Studies suggest that nerve cells (neurons) are metabolically protected against degeneration using low-level methylene blue and near-infrared light and therefore may help to prevent and provide treatment for neurodegenerative disorders such as Parkinson’s, Alzheimer’s and Motor Neuron Disease.

The study at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4428125/ highlights these two very different, but beneficial, chemical-physical interventions and the exciting future for therapeutic applications.