Research-use-only context. This article summarizes published third-party scientific literature and laboratory practice. It is not medical advice, not a therapeutic or performance claim, and not a usage guide. US Prime Peptides products are supplied strictly for in vitro laboratory research and are not for human or veterinary use.
This article explains what GHK-Cu is as a molecule, where the tripeptide was first found, and what the peer-reviewed literature reports for it in cell culture, in rodent and guinea-pig wound models, and in the small number of human-tissue and gene-expression studies that exist. It separates findings that depend on bound copper from findings seen with the free peptide, and it closes with what has not been established and what a research certificate for the complex should show.
GHK is a three-residue copper-binding peptide first isolated from human plasma
GHK is the tripeptide glycyl-L-histidyl-L-lysine, molecular formula C14H24N6O4 and molecular weight about 340.4 daltons (PubChem CID 73587, CAS 49557-75-7). Pickart and Thaler reported it in a 1973 Nature New Biology paper as an activity in human serum, associated with the albumin fraction, that changed the behavior of liver cells in culture: it prolonged survival of normal hepatocytes and increased growth in hepatoma cells. A companion 1973 paper in Biochemical and Biophysical Research Communications showed that a synthetic tripeptide reproduced the activity. Older literature also calls it prezatide; cosmetic ingredient dictionaries list the complex as copper tripeptide-1.
The peptide's defining chemistry is its affinity for copper(II). Freedman and colleagues, in a 1982 Biochemistry paper, used optical, electron paramagnetic resonance, and electron spin-echo spectroscopy to show that at neutral pH GHK forms a one-to-one complex with Cu(II) coordinated through nitrogen atoms, one of them the histidine imidazole. The polymeric, oxygen-bridged structure seen by X-ray crystallography in the solid state does not persist in solution. Laussac, Haran, and Sarkar reached a compatible conclusion in a 1983 Biochemical Journal study, interpreting the EPR hyperfine pattern between pH 6 and 9.6 as three nitrogen donors and one oxygen donor around copper in a square-planar arrangement. That complex, GHK-Cu, is what research vials labeled "GHK-Cu" contain (PubChem CID 71587328, CAS 89030-95-5, cation formula C14H23CuN6O4+).
Lane and colleagues added a second source of the sequence in a 1994 Journal of Cell Biology paper: proteolysis of the matrix protein SPARC releases KGHK, GHK, and longer peptides containing them, and KGHK stimulated endothelial cord formation in vitro without prior copper loading. Maquart's group noted in 1988 that the GHK triplet also occurs in the alpha-2 chain of type I collagen, which is why several authors describe the tripeptide as a fragment that proteases could liberate from damaged matrix.
What fibroblast and keratinocyte culture studies report
The densest part of the literature is work in cultured skin cells, mostly from one French group. Maquart and colleagues, in a 1988 FEBS Letters paper, reported that GHK-Cu increased collagen synthesis in fibroblast cultures. The effect began between 1 picomolar and 10 picomolar, peaked at 1 nanomolar, and was independent of any change in cell number. Wegrowski, Maquart, and Borel followed in 1992 in Life Sciences with radiolabel incorporation studies in normal human fibroblasts: GHK-Cu increased total glycosaminoglycan synthesis in a concentration-dependent and biphasic way, with the maximum at 1 to 10 nanomolar, preferentially raised dermatan sulfate in the medium and heparan sulfate in the cell layer, and did not change hyaluronic acid.
Siméon and colleagues published two 2000 papers that widen the picture to matrix turnover rather than matrix deposition alone. In Life Sciences they reported that GHK-Cu raised matrix metalloproteinase-2 protein and mRNA in dermal fibroblast cultures and also raised the inhibitors TIMP-1 and TIMP-2. Importantly, the MMP-2 effect was reproduced by copper ions alone and not by the tripeptide without copper. In the Journal of Investigative Dermatology the same group reported that GHK-Cu increased decorin mRNA in rat dermal fibroblasts while leaving biglycan unchanged.
Two later studies add growth-factor and cytokine readouts. Pollard and colleagues, in a 2005 Archives of Facial Plastic Surgery paper, grew primary human dermal fibroblasts from previously irradiated tissue in serum-free medium with 1 nanomolar GHK-Cu and measured faster population doubling plus higher early output of basic fibroblast growth factor and VEGF. Gruchlik and colleagues reported in a 2012 Acta Poloniae Pharmaceutica study that GHK, GGH, their copper complexes, and copper chloride alone all reduced TNF-alpha-driven interleukin-6 secretion in normal human dermal fibroblasts. Choi and colleagues, in a 2012 Journal of Peptide Science paper, studied copper-free GHK in cultured human keratinocytes and skin-equivalent models, reporting more proliferation, stronger alpha-6 and beta-1 integrin staining along the basement membrane, and more p63-positive cells.
What rodent and guinea-pig wound models report
The main in vivo series uses the stainless-steel wound chamber in rats. Maquart and colleagues, in a 1993 Journal of Clinical Investigation paper, implanted wire-mesh cylinders on the backs of rats and delivered GHK-Cu or saline into the chamber. Chambers that received GHK-Cu accumulated more dry mass, DNA, total protein, collagen, and glycosaminoglycan in a concentration-dependent way; type I and type III collagen mRNAs rose while TGF-beta mRNA did not; and a control tripeptide, Glu-His-Pro, had no effect. Siméon's 2000 Journal of Investigative Dermatology study used the same model and reported more chondroitin and dermatan sulfate, higher decorin mRNA, and lower biglycan mRNA.
Not every animal result points the same way. Buffoni, Pino, and Dal Pozzo, in a 1995 Arch Int Pharmacodyn Ther paper, applied GHK-Cu and three synthetic analogs to dorsal skin wounds in guinea pigs and observed slower tissue reorganization and delayed fibroblast activation compared with controls; in culture at 100 nanomolar the same compounds reduced fibroblast replication while increasing collagen expression. Parker and colleagues, in a 2013 Otolaryngology-Head and Neck Surgery study, applied a GHK-Cu gel to dorsal skin flaps in previously irradiated Sprague-Dawley rats and found no difference from control ointment in ischemic flap area, caveolin-1-stained vessel counts, vessel luminal area, or VEGF staining. Both results are worth keeping in view when reading reviews that list only positive findings.
Gene-expression studies: the Connectivity Map and the "4,000 genes" claim
The claim that GHK modulates thousands of human genes comes from in silico comparison against the Broad Institute Connectivity Map, not from a transcriptome experiment on GHK-exposed tissue. Campbell and colleagues, in a 2012 Genome Medicine paper, profiled gene expression in 64 lung-tissue samples from eight smokers with emphysema, derived a 127-gene signature that tracked regional tissue destruction, and queried the Connectivity Map for compounds whose expression profiles opposed that signature. GHK was one of the hits. They then exposed human lung fibroblasts to GHK and found that it reproduced a TGF-beta-like gene-expression pattern and changed fibroblast contraction of collagen gels. That is a real experiment, but it is a single-cell-type follow-up to a database query.
Pickart, Vasquez-Soltero, and Margolina built on that database approach in a 2014 BioMed Research International paper and a 2015 review in the same journal, reporting that the Connectivity Map profile associated with GHK shifts expression of a large set of genes, which they summarize as "resetting" expression toward a healthier state. Two cautions apply. The Connectivity Map profile for a compound is a reference signature generated in a few cancer cell lines, so a gene count derived from it says nothing about any specific tissue. And the lead author discovered the peptide and holds commercial interests in it, so an independent transcriptome replication would carry more weight; none in primary human tissue has been published.
Cosmetic-science history and human-tissue data
GHK-Cu has been used as a cosmetic ingredient since the 1990s under the INCI name copper tripeptide-1, and most of the "human" literature is either cosmetic-formulation work or in vitro work on excised human skin. Hostynek, Dreher, and Maibach, in a 2011 Inflammation Research paper, applied a 0.68 percent aqueous solution of glycyl-L-histidyl-L-lysine cuprate diacetate to isolated stratum corneum, heat-separated epidermis, and dermatomed human skin in flow-through diffusion cells and measured copper in the receptor fluid by ICP-MS. They reported a permeability coefficient of about 2.4 x 10^-4 centimeters per hour through dermatomed skin, with a substantial copper depot retained in the tissue: a measurement of where copper goes in excised skin, not a clinical outcome.
Controlled studies of cosmetic creams exist, but they are small, mostly industry-run, and reported inside reviews rather than as stand-alone trials with raw data. No randomized trial of GHK-Cu as a drug in humans has been published, and the compound is not an approved drug in any jurisdiction. A research vial of GHK-Cu is a chemical for in vitro work, not a cosmetic product.
Copper versus peptide: the question the literature has not settled
Several of the strongest cell-culture effects were reproduced by copper salts alone, and several others were obtained with copper-free GHK. The table summarizes which is which.
| Readout | Model | Needs copper? | Source |
|---|---|---|---|
| Collagen synthesis | Fibroblast culture | Studied as GHK-Cu; free peptide not compared | Maquart 1988 |
| Glycosaminoglycan synthesis | Human fibroblasts | Studied as GHK-Cu | Wegrowski 1992 |
| MMP-2 expression | Dermal fibroblasts | Yes: Cu(II) alone works, GHK alone does not | Siméon 2000 |
| IL-6 suppression after TNF-alpha | Human dermal fibroblasts | No: GHK, GHK-Cu, and CuCl2 all active | Gruchlik 2012 |
| Keratinocyte proliferation, integrins | Keratinocytes, skin equivalents | No: copper-free GHK used | Choi 2012 |
| Endothelial cord formation | Endothelial cells, in vivo assay | No: KGHK active without prior Cu loading | Lane 1994 |
| Ferritin iron release | Cell-free | Yes: studied as GHK:Cu(II) | Miller 1990 |
The practical consequence: a certificate for a GHK-Cu lot should state the copper content or the peptide-to-copper ratio, because free GHK and the 1:1 complex are different reagents. US Prime Peptides lists GHK-Cu 50 mg with a lot-matched certificate covering identity by mass spectrometry, purity by HPLC, net peptide content, endotoxin, sterility, and heavy metals by ICP-MS, the last of which is where the copper line appears. The same peptide is a component of the three-part GLOW blend, whose certificate must identify each component separately; see how to read a blend certificate and the companion overviews of BPC-157 and TB-500 for the other two components.
What is not established
Three gaps stand out. There is no peer-reviewed randomized human trial of GHK-Cu for any indication; the human data are excised-skin permeation measurements and small cosmetic studies. The gene-expression claims rest on a database signature and one lung-fibroblast follow-up, not on tissue transcriptomes from exposed subjects. And the animal literature contains negative results, in guinea-pig skin and in irradiated rat flaps, that the review literature rarely cites. A reader should regard the mechanistic cell-culture work from 1988 to 2000 as the solid core of the field and everything downstream of the Connectivity Map as hypothesis. For how a short sequence like this is written and read, see how to read a peptide sequence.
Frequently Asked Questions
What is the difference between GHK and GHK-Cu?
GHK is the free tripeptide glycyl-L-histidyl-L-lysine. GHK-Cu is its one-to-one complex with copper(II), held through three nitrogen atoms and one oxygen atom of the peptide. Some published effects require the copper and are reproduced by copper salts alone; others were obtained with the copper-free peptide, so the two are not interchangeable.
Is GHK-Cu an approved drug?
No. GHK-Cu is not an approved drug in the United States or elsewhere. It is used as a cosmetic ingredient under the name copper tripeptide-1, and it is supplied to laboratories as a research chemical. A research vial is neither a drug nor a cosmetic product.
What does the research on GHK-Cu actually show?
Fibroblast studies report increased collagen, glycosaminoglycan, decorin, and MMP-2 output at nanomolar concentrations, and rat wound-chamber studies report more matrix accumulation. Negative results exist in guinea-pig skin and irradiated rat flaps. No randomized human trial has been published.
Does GHK-Cu really change 4,000 genes?
That figure comes from comparing GHK's reference profile in the Broad Institute Connectivity Map, a database built from a few cancer cell lines, against disease signatures. It is an in silico result, supported by one experiment in cultured lung fibroblasts, and has not been replicated by transcriptome sequencing of human tissue exposed to the peptide.
Citations
- Pickart L, Thaler MM. Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nat New Biol. 1973;243:85-87. PMID 4349963
- Freedman JH, Pickart L, Weinstein B, et al. Structure of the glycyl-L-histidyl-L-lysine-copper(II) complex in solution. Biochemistry. 1982;21:4540-4544. PMID 6291585
- Laussac JP, Haran R, Sarkar B. N.m.r. and e.p.r. investigation of the interaction of copper(II) and glycyl-L-histidyl-L-lysine, a growth-modulating tripeptide from plasma. Biochem J. 1983;209:533-539. PMID 6303307
- Maquart FX, Pickart L, Laurent M, et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988;238:343-346. PMID 3169264
- Miller DM, DeSilva D, Pickart L, Aust SD. Effects of glycyl-histidyl-lysyl chelated Cu(II) on ferritin dependent lipid peroxidation. Adv Exp Med Biol. 1990;264:79-84. PMID 2244543
- Wegrowski Y, Maquart FX, Borel JP. Stimulation of sulfated glycosaminoglycan synthesis by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. Life Sci. 1992;51:1049-1056. PMID 1522753
- Maquart FX, Bellon G, Chaqour B, et al. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds. J Clin Invest. 1993;92:2368-2376. PMID 8227353
- Lane TF, Iruela-Arispe ML, Johnson RS, Sage EH. SPARC is a source of copper-binding peptides that stimulate angiogenesis. J Cell Biol. 1994;125:929-943. PMID 7514608
- Buffoni F, Pino R, Dal Pozzo A. Effect of tripeptide-copper complexes on the process of skin wound healing and on cultured fibroblasts. Arch Int Pharmacodyn Ther. 1995;330:345-360. PMID 8836453
- Siméon A, Emonard H, Hornebeck W, Maquart FX. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 2000;67:2257-2265. PMID 11045606
- Siméon A, Wegrowski Y, Bontemps Y, Maquart FX. Expression of glycosaminoglycans and small proteoglycans in wounds: modulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu(2+). J Invest Dermatol. 2000;115:962-968. PMID 11121126
- Pollard JD, Quan S, Kang T, Koch RJ. Effects of copper tripeptide on the growth and expression of growth factors by normal and irradiated fibroblasts. Arch Facial Plast Surg. 2005;7:27-31. PMID 15655171
- Hostynek JJ, Dreher F, Maibach HI. Human skin penetration of a copper tripeptide in vitro as a function of skin layer. Inflamm Res. 2011;60:79-86. PMID 20721598
- Campbell JD, McDonough JE, Zeskind JE, et al. A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK. Genome Med. 2012;4:67. PMID 22937864
- Choi HR, Kang YA, Ryoo SJ, et al. Stem cell recovering effect of copper-free GHK in skin. J Pept Sci. 2012;18:685-690. PMID 23019153
- Gruchlik A, Jurzak M, Chodurek E, Dzierzewicz Z. Effect of Gly-Gly-His, Gly-His-Lys and their copper complexes on TNF-alpha-dependent IL-6 secretion in normal human dermal fibroblasts. Acta Pol Pharm. 2012;69:1303-1306. PMID 23285694
- Parker NP, Ardeshirpour F, Schmechel SC, et al. Effects of topical copper tripeptide complex on wound healing in an irradiated rat model. Otolaryngol Head Neck Surg. 2013;149:384-389. PMID 23744835
- Pickart L, Vasquez-Soltero JM, Margolina A. GHK and DNA: resetting the human genome to health. Biomed Res Int. 2014;2014:151479. PMID 25302294
- Pickart L, Vasquez-Soltero JM, Margolina A. GHK peptide as a natural modulator of multiple cellular pathways in skin regeneration. Biomed Res Int. 2015;2015:648108. PMID 26236730
This article is for laboratory research reference only. US Prime Peptides products are supplied strictly for in vitro research. Not for human consumption.
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