What it is
GHK-Cu is the copper(II) complex of the tripeptide glycyl-L-histidyl-L-lysine (GHK), described by Loren Pickart and colleagues as a component of human plasma. It was developed by the company ProCyte as a wound gel (Iamin) for diabetic foot ulcers and later became a common ingredient in cosmetic skin products. Most published research uses cultured skin cells and wound models, and much of the review literature comes from Pickart's own group.
Mechanism of action
GHK binds copper(II) tightly, and the copper complex is the form most studied for skin. In fibroblast cultures, Maquart et al. (1988) reported that GHK-Cu stimulated collagen synthesis at very low concentrations, starting between 10⁻¹² and 10⁻¹¹ M and peaking at 10⁻⁹ M, without changing cell numbers. In adult human dermal fibroblasts, Badenhorst et al. (2016) found that the complex raised collagen and elastin production and increased expression of both matrix-degrading enzymes (MMP1, MMP2) and their inhibitor TIMP1, which suggests it adjusts matrix turnover rather than simply adding matrix. A second line of work concerns gene expression. Campbell et al. (2012) identified GHK by screening for compounds whose gene-expression effects oppose a signature linked to emphysema severity in lung tissue, and Pickart and Margolina (2018) argue in a review that broad gene-level effects could explain the range of actions reported. How well the complex penetrates intact human skin is not settled.
What it’s most studied for
Researchers have examined GHK-Cu mainly for skin matrix and wound repair. The early work measured collagen synthesis in cultured fibroblasts and connective tissue build-up in rat wound chambers, which led to clinical development of a topical gel for diabetic foot ulcers in the early 1990s. After that program stalled, interest moved to cosmetics: facial creams and serums tested for wrinkles, firmness and skin density, mostly in small studies. A third, smaller line uses gene-expression screening to ask whether GHK opposes tissue-destruction signatures, for example in emphysematous lung tissue. GHK-Cu is also sold in vials, but the human studies found for this summary were all topical.
Notable findings
Each finding carries the species or population it was observed in and the dose that study used. Doses are reported as research context, exactly as published. They are not guidance.
Collagen synthesis in fibroblast cultures
Maquart et al. (1988), with Pickart as a co-author, added GHK-Cu to fibroblast cultures and measured collagen synthesis. Stimulation began at concentrations between 10⁻¹² and 10⁻¹¹ M and reached its maximum at 10⁻⁹ M, and it was independent of any change in cell number. This is the foundational paper for the collagen claims made about the peptide.
- Dose studied
- GHK-Cu added to culture medium across picomolar to nanomolar concentrations, maximal effect at 10⁻⁹ M (fibroblast cultures)
[1] Maquart FX et al. · 1988 · PMID 3169264 ↗
Connective tissue build-up in rat wounds
Maquart et al. (1993) implanted wire-mesh wound chambers under the skin of rats and injected saline or GHK-Cu into them. The chambers showed a dose-related rise in dry weight, DNA, total protein, collagen and glycosaminoglycans, with collagen synthesis rising about twice as much as other protein. Type I and III collagen mRNA increased while TGF-beta mRNA did not, and a control tripeptide had no significant effect.
- Dose studied
- Saline or several concentrations of GHK-Cu injected sequentially into subcutaneous wound chambers (rats)
[2] Maquart FX et al. · 1993 · PMID 8227353 ↗
Diabetic foot ulcer gel trials
Mulder et al. (1994) tested a GHK-Cu gel (Iamin) against vehicle in people with diabetic neuropathic foot ulcers, all of whom also received debridement, pressure-relieving footwear and education. The paper reports enhanced ulcer healing with the peptide, but secondary sources give conflicting closure figures, so none is given here. In 1994 trade press reported that a larger phase III trial of the same gel, 511 patients at 30 centers, did no better than placebo on wound-size reduction or full closure.
- Dose studied
- Daily topical application of a metered dose of GHK-Cu gel, with vehicle gel as control (adults with diabetic neuropathic foot ulcers)
[3] Mulder GD et al. · 1994 · DOI 10.1046/j.1524-475X.1994.20406.x ↗
Facial wrinkles in a double-blind trial
Badenhorst et al. (2016) had 40 women aged 40 to 65 apply GHK-Cu in a lipid nano-carrier serum, the vehicle serum alone, or a commercial product containing Matrixyl 3000 to the face for eight weeks. The authors reported wrinkle volume 55.8% lower and wrinkle depth 32.8% lower with GHK-Cu than with the vehicle, and wrinkle volume 31.6% lower than with the Matrixyl 3000 product. It is one of the few controlled cosmetic trials of the peptide, but it is small and appeared in a low-profile journal.
- Dose studied
- GHK-Cu in a lipid-based nano-carrier serum applied to facial skin twice daily for 8 weeks; vehicle serum and a Matrixyl 3000 product as controls (women aged 40 to 65)
Matrix gene expression in human skin cells
In the laboratory arm of the same paper, Badenhorst et al. (2016) exposed adult human dermal fibroblasts to GHK-Cu. All tested concentrations increased collagen and elastin production and TIMP1 expression, while MMP1 and MMP2 expression rose only at the lowest concentration. Higher ratios of TIMP to MMP expression went along with more collagen and elastin.
- Dose studied
- 0.01, 1 and 100 nM in culture medium (adult human dermal fibroblasts)
Study quality
Most GHK-Cu evidence comes from cultured cells and animal wound models such as rat wound chambers; human data are limited to a few topical trials. The cell and rat work is controlled but comes largely from a small number of groups, several including Pickart, who first described the peptide. The published diabetic ulcer trial (Mulder et al. 1994) was randomized and blinded, but trade press later reported that a phase III trial of 511 patients did no better than placebo, and no full paper of those results was found. Cosmetic evidence varies widely in quality: the 40-person double-blind trial by Badenhorst et al. (2016) had a vehicle control and an active comparator, while many claims in marketing trace to small uncontrolled pilots or to reviews by the peptide's originator. None of the topical studies was designed or sized to assess safety, and no published safety data on injected GHK-Cu were found.
References
- 1
- 2In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds. Journal of Clinical Investigation. PMID 8227353
- 3Enhanced healing of ulcers in patients with diabetes by treatment with glycyl-l-histidyl-l-lysine copper. Wound Repair and Regeneration. DOI 10.1046/j.1524-475X.1994.20406.x
- 4ProCyte's lead product no better than placebo. The Pharma Letter (trade press).
- 5Effects of GHK-Cu on MMP and TIMP expression, collagen and elastin production, and facial wrinkle parameters. Journal of Aging Science.
- 6A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK. Genome Medicine. PMID 22937864
- 7Regenerative and protective actions of the GHK-Cu peptide in the light of the new gene data. International Journal of Molecular Sciences. PMID 29986520
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