The primary means for photomodulated upregulation of cell activity for collagen synthesis by LED is the activation of energy switching mechanisms in mitochrondria, the energy source for cellular activity. Cytochrome molecules are believed to be responsible for the light absorption in mitochrondria. Cytochromes are synthesized from protoporphyrin IX and absorb wavelengths of light from 562 nm to 600 nm. It is believed that LED light absorption causes conformational changes in antenna molecules within the mitochrondrial membrane. Proton translocation initiates a pump which ultimately leads to energy for conversion of ADP to ATP. This essentially recharges the “cell battery” and provides more energy for cellular activity.
Others have confirmed that mitochrondial ATP availability can influence cellular growth and reproduction, with lack of mitochrondrial ATP associated with oxidative stress [31]. Cellular aging may be associated with decreased mitochrondial DNA activity [32]. Earlier work has also demonstrated rapid ATP production within mitochrondia of cultured fibroblasts exposed to 590 nm/870 nm yellow/IR LED light only with the proper pulsing sequence [8,33]. New ATP production occurs rapidly after LED photomodulation, triggering subsequent metabolic activity of fibroblasts [18] . There also appear to be receptor-like mechanisms, which result in the modulation of the expression of gene activity producing up – or down-regulation of gene activity, as well as a wide-ranging cell signaling pathway actions. The choice of photomodulation parameters plays a vital role in determining the overall pattern of gene up – or down – regulation. In our experience, the use of LED yellow/IR light without proper pulsing sequence leads to minimal or no consequences on mitochrondrial ATP production.
LED arrays using LILT for photomodulation are useful for collagen stimulation, textural smoothing, and reduction of inflammation. Pilot wound-healing studies show slightly accelerated wound resolution. Cellular rescue from UV damage and other toxic insults has been shown in small studies. Our combined multiyear experience and clinical observations confirm that combinations of thermal nonablative photorejuvenation and nonthermal LED photomodulation have a synergistic effect. LED photomodulation is delivered immediately, subsequent to the thermal-based treatment for its antiinflammatory effects, which may reduce the thermally induced erythema and edema of nonablative treatments. Delivery of LED light immediately pre – and post-thermal injury appears to potentiate the effect, as observed from our clinical experience.
A significant study with age and radiation-matched controls for radiation dermatitis indicates that there is a powerful potential to further utilize the specific antiinflammatory and cell-rescue properties of LED photomodulation. Radiation-treated patients may have not only reduced side effects, but also smoother skin in the treated areas over a long term. Preliminary data from DNA microarray analysis of the entire human genome of certain skin cell lines after LED photomodulation, and also after UV injury and subsequent LED therapy are currently being analyzed and they support a versatile role for LED photomodulation in enhancing cellular energy production, as well as diverse effects on gene expression. LED photomodulation appears to negate some of the negative aspects of UV exposure. Many clinical and basic science-research pathways await further exploration for this novel nonthermal, low-risk technology.