GHK-Cu

Overview

GHK-Cu is the copper-bound form of the endogenous tripeptide glycyl-L-histidyl-L-lysine, first isolated from human plasma in 1973 by Loren Pickart at the University of California, San Francisco. The peptide binds divalent copper (Cu²⁺) at sub-nanomolar affinity, and the copper-bound form is the species responsible for most of the biological activity reported in the literature.

Plasma concentrations of GHK fall substantially across the lifespan: roughly 200 ng/mL at age 20 to around 80 ng/mL at age 60. This age-related decline has motivated decades of research into GHK-Cu as a candidate tissue-repair and cytoprotective agent, with particular focus on dermal connective tissue, wound healing, hair follicle biology and the gene-expression profile of senescent fibroblasts.

Unlike most peptides discussed on this site, GHK-Cu has been incorporated into commercial cosmetic preparations for decades, and its dermatological safety profile is well established in that context. The longevity-oriented research described here, however, treats it as a research compound: a probe for studying connective-tissue and cellular-repair pathways in laboratory models.

Mechanism of action

Three mechanistic threads dominate the GHK-Cu literature. The first is copper trafficking: GHK acts as a copper carrier, delivering Cu²⁺ to enzymes that require it as a cofactor (lysyl oxidase, superoxide dismutase, cytochrome c oxidase) and removing free copper from oxidative-stress-promoting contexts. This dual role — physiological copper delivery without leaving redox-active free copper in tissues — is unusual and underpins many of the downstream effects.

The second thread is gene-expression modulation. In a 2012 genome-wide microarray study, Pickart and colleagues reported that GHK at low-nanomolar concentrations modulated expression of approximately 4,000 human genes — roughly one-third of the human genome — including up-regulation of antioxidant-defence genes, DNA-repair genes and connective-tissue components, and down-regulation of inflammatory-response and metastasis-associated genes. The effect was consistent enough that Connectivity Map analysis classified GHK as a 'reverser' of the gene-expression signature of multiple cancer and inflammatory tissues.

The third thread is direct effects on fibroblast and stem-cell behaviour. In vitro, GHK-Cu increases proliferation of dermal fibroblasts, stimulates synthesis of collagen, elastin, glycosaminoglycans and proteoglycans, and supports differentiation of certain progenitor populations. In ex vivo skin models, repeated application produces measurable improvement in dermal thickness and connective-tissue organisation.

Anti-inflammatory effects are mediated in part through suppression of NF-κB-driven cytokine release in macrophages and reduction of TNF-α-induced chemokine output in keratinocytes. These observations have made GHK-Cu a recurring reference compound in studies of inflammaging — the chronic low-grade inflammatory state characteristic of aged tissues.

Research history

GHK was first identified by Pickart as a 'growth factor' fraction in albumin from young donors that stimulated regenerative gene expression in old hepatocyte cultures. The Cu²⁺-bound complex was characterised through the late 1970s and 1980s, with successive papers establishing the wound-healing, antioxidant and gene-regulatory effects.

The 1990s and 2000s saw substantial dermatological development; copper tripeptide-1 is recognised by the INCI nomenclature for cosmetic use and appears in topical formulations from multiple commercial brands. The genome-wide microarray work published from 2009 onward — particularly Hong et al. 2012 and Pickart and Margolina's 2018 review — re-positioned GHK-Cu in the longevity literature by demonstrating that its activity is not limited to skin but extends to a broad anti-ageing gene-expression signature.

Summarised studies