Copper tripeptide (GHK-Cu), a naturally occurring tripeptide, is first isolated from human plasma, but can be found in saliva and urine. During wound healing, Copper tripeptide may be freed from existing extracellular proteins via proteolysis and serves as a chemoattractant for inflammatory and endothelial cells. Copper tripeptide has been shown to increase messenger RNA production for collagen, elastin, proteoglycans, and glycosaminoglycans in fibroblasts. Copper tripeptide is a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration.