Figure 4.

Mechanisms of photobiomodulation (PBM). Interaction of light and biological tissues leads to generation of transient and extremely reactive chemical intermediates, reactive oxygen species (ROS), in both extracellular and intracellular compartments. These ROS can react rapidly with various components inducing potent cellular responses. Among the best characterized pathways, intracellular photoabsorption by cytochrome C oxidase disrupts mitochondrial function, resulting in increased ATP synthesis and nitric oxide (NO) release. A recently elucidated extracellular pathway noted generation of ROS-mediated activation of transforming growth factor-β1 (TGF-β1) following PBM therapy. Both intracellular and extracellular pathways induce specific signal transduction pathways that recruit transcription factors leading to a concerted gene expression contributing to therapeutic PBM effects on wound healing.