GHK-Cu (Glycyl-L-histidyl-L-lysine:copper 2+) is a naturally occurring tripeptide-copper complex found in human plasma, saliva, and urine. First isolated in 1973, it has been studied extensively for its pleiotropic biological activities. Research has documented its roles in collagen and glycosaminoglycan synthesis, angiogenesis, anti-inflammatory cytokine modulation, and gene expression regulation. In wound healing models, GHK-Cu has demonstrated acceleration of tissue repair processes and antioxidant enzyme upregulation. It is also widely used in dermatological research for its documented effects on skin barrier function.