GHK-Cu
A copper-binding tripeptide that modulates the activity of over 4,000 genes; principal effects include up-regulation of antioxidant defenses, anti-inflammatory signaling, and stem-cell-friendly gene programs.
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (GHK), a sequence found endogenously in human plasma, saliva, and urine. Plasma GHK concentrations decline from approximately 200 ng/mL at age 20 to roughly 80 ng/mL by age 60, paralleling the broad decline in regenerative capacity associated with aging.
The signaling profile of GHK-Cu is unusually broad. Transcriptomic studies have documented modulation of more than 4,000 human genes, predominantly those involved in antioxidant defense (e.g., SOD, catalase), anti-inflammatory signaling, DNA repair, mitochondrial biogenesis, and matrix remodeling. The copper component is essential: GHK alone produces a fraction of the gene-expression changes observed with the copper-complexed form, and the affinity of GHK for Cu(II) is extraordinarily high (Kd ≈ 10^-16 M).
Documented effects in cell and animal models include accelerated wound re-epithelialization, hair follicle stimulation, reduction of fibrotic remodeling, and partial reversal of the aged-skin transcriptome. GHK-Cu is found in numerous cosmeceutical preparations for skin applications, but injectable use remains investigational and is not approved by regulatory bodies for therapeutic indications.