What is GHK-Cu? The copper peptide research so far

What is GHK-Cu? It is a small tripeptide, the three amino acids glycine, histidine and lysine joined in that order, glycyl-L-histidyl-L-lysine or GHK, that occurs naturally in human plasma, saliva and urine ^[1]. In the FDA's substance register, GHK itself is named prezatide ^[16], and GHK-Cu prezatide copper, with GHK copper and copper tripeptide-1 among its synonyms ^[17]. It is proposed to function as a complex with copper 2+, which a 2015 review describes as accelerating wound healing and skin repair ^[1]. The peptide was isolated in 1973 by Pickart as an activity in human albumin that caused old human liver tissue to synthesise proteins like younger tissue ^[1]. In plasma its level is about 200 ng/mL at age 20 and declines to 80 ng/mL by age 60, a fall that reviews describe as coinciding with the noticeable decrease in the regenerative capacity of an organism ^[1], ^[2].

• Fibroblast cultures, where GHK-Cu's effect on collagen synthesis and growth factor production has been measured directly ^[5], ^[8], ^[10].
• Rat wound models, from implanted wound chambers to ischemic and irradiated skin flaps ^[6], ^[7], ^[9].
• Lung-tissue gene-expression profiles, in an analysis of emphysema severity in COPD ^[3].
• Human skin measured in vitro, for how much applied copper penetrates each layer ^[11].
• People, in a 1994 diabetic ulcer trial and a Phase 2 trial registered in 2026 ^[13], ^[14].

1. 1973

   Pickart isolates GHK from human plasma, as an activity in human albumin that causes old human liver tissue to synthesise proteins like younger tissue.[1]

2. 1980

   A Nature paper reports that the tripeptide forms complexes with copper(II) and enhances the uptake of the metal into cultured hepatoma cells.[4]

3. 1988

   Maquart and colleagues report that GHK-Cu stimulates collagen synthesis in fibroblast cultures, maximal at 10(-9) M.[5]

4. 1993

   The same group reports that GHK-Cu increases collagen and glycosaminoglycan accumulation in rat experimental wounds in vivo, in a concentration-dependent way.[6]

5. 1994

   A multicentre, randomised, evaluator-blinded, placebo-controlled trial reports that a GHK-Cu gel increases the closure of diabetic neuropathic plantar ulcers over standard wound care and vehicle.[13]

6. 2011

   An in vitro study measures how much copper applied as GHK-Cu passes through isolated human stratum corneum, epidermis and dermatomed skin over 48 hours.[11]

7. 2012

   Using the Connectivity Map, researchers identify GHK as a compound that reverses the gene-expression signature of emphysematous lung destruction in COPD.[3]

8. 2026

   A registered Phase 2 trial begins recruiting to test a topical GHK-Cu gel against a vehicle gel on standardised acute skin wounds in healthy adults.[14]

The 1980 Nature paper that first connected the peptide to copper describes it as GHL, glycyl-L-histidyl-lysine, added at nanomolar concentrations to a wide group of cultured cell systems, where it produced a disparate set of responses ranging from the stimulation of growth and differentiation to outright toxicity ^[4]. During its isolation the tripeptide co-purified with approximately equimolar copper and about one-fifth molar iron, and the authors report that the compound readily forms complexes with copper(II) and enhances the uptake of the metal into cultured hepatoma cells ^[4]. Maximal effects on those cells were seen when the peptide was added together with copper and iron to the growth medium ^[4].

The same paper reports that several tripeptides carrying a histidyl-lysyl linkage were nearly as active as GHL, and notes a homology between the tripeptide and the copper-transport sites on two carrier proteins, albumin and alpha-fetoprotein, where the cupric atom binds to a histidyl residue next to a basic residue; that resemblance is what suggested the tripeptide might act as a copper-transport factor ^[4]. Later reviews report that GHK stimulates both the synthesis and the breakdown of collagen and glycosaminoglycans while modulating the activity of metalloproteinases and their inhibitors ^[1]. A 2018 review lists blood-vessel and nerve outgrowth, increased collagen, elastin and glycosaminoglycan synthesis, and support for the function of dermal fibroblasts among the actions it attributes to GHK ^[2].

Several of the findings in this guide come from the Connectivity Map, a tool built by the Broad Institute of MIT and Harvard: a publicly available library of transcriptional responses to known perturbagens, substances that modulate gene expression ^[2]. Researchers use it to ask which of many catalogued compounds produces, or reverses, a given pattern of gene-expression change ^[2].

Using the Connectivity Map, researchers established that GHK-Cu is able to up- and downregulate a significant number of human genes: a 2018 review reports that the share of human genes stimulated or suppressed by GHK, at a change of 50% or more, is 31.2%, with 59% of those changed genes increased in expression and 41% suppressed ^[2]. A 2015 review states the broader figure as at least 4,000 human genes up- or downregulated, and reports that GHK significantly increased the expression of DNA-repair genes specifically, with 47 genes stimulated and 5 suppressed at that same 50%-or-more threshold ^[1]. Both reviews are co-written by Pickart, who first isolated the peptide in 1973 ^[1], ^[2].

The most detailed single study behind this picture is a 2012 gene-expression analysis of chronic obstructive pulmonary disease, COPD ^[3]. The researchers profiled gene expression in lung tissue taken from regions of varying emphysema severity within the same lung, in eight regions across eight lungs from smokers with COPD, 64 samples in total, with regional severity quantified from micro-CT scans ^[3]. They identified 127 genes whose expression was significantly associated with regional emphysema severity: genes involved in inflammation, such as the B-cell receptor signalling pathway, increased with worsening destruction, while genes enriched in tissue-repair processes, including the transforming growth factor beta, TGFβ, pathway, actin organisation and integrin signalling, decreased ^[3]. Using the Connectivity Map, the researchers then identified GHK as a compound that could reverse this gene-expression signature and induce patterns consistent with TGFβ pathway activation ^[3]. They tested that prediction directly: treating human fibroblasts with GHK reproduced the gene-expression pattern TGFβ itself produces, led to organisation of the actin cytoskeleton, and raised the expression of integrin β1 ^[3]. In fibroblasts taken from COPD lungs, which had an impaired ability to contract and remodel collagen, adding either GHK or TGFβ restored that function ^[3].

The earliest of these studies measured collagen production directly. In 1988, Maquart and colleagues reported that GHK-Cu stimulates collagen synthesis in fibroblast cultures: the effect began between 10(-12) and 10(-11) M and was maximal at 10(-9) M, independent of any change in cell number ^[5]. The same paper notes that the GHK sequence occurs as a natural triplet within the alpha 2(I) chain of type I collagen, and suggests the tripeptide might be released there by proteases at a wound site ^[5].

A follow-up study in 1993 moved from cultured cells to a living animal: stainless-steel wire-mesh cylinders were implanted subcutaneously on the backs of rats, and the wound chambers received sequential injections of saline or various concentrations of GHK-Cu ^[6]. The GHK-Cu chambers showed a concentration-dependent increase in dry weight, DNA, total protein, collagen and glycosaminoglycan content, with the stimulation of collagen synthesis twice that of non-collagen proteins; type I and type III collagen mRNAs increased, though TGF beta mRNA did not ^[6]. A control tripeptide, L-glutamyl-L-histidyl-L-proline, had no significant effect ^[6].

A 2003 study tested a topical GHK-Cu gel on ischemic wounds in 24 adult male Sprague-Dawley rats, divided into a treated group, a vehicle group and an untreated control, with 6-mm full-thickness wounds created within an ischemic skin flap and traced daily for 13 days ^[7]. Wound area fell significantly more in the treated group than in the control on days 3 to 5, 6 to 9 and 11 to 13, and more than in the vehicle group on days 3 and 9 ^[7]. By day 13, initial wound area had decreased by 64.5% in the treated group, 45.6% in the vehicle group and 28.2% in the untreated control, and biopsies on days 6, 10 and 13 showed the treated wounds carried significantly lower concentrations of tumour necrosis factor alpha, and of two matrix metalloproteinases, MMP-2 and MMP-9, than the control ^[7].

A 2005 study looked at whether GHK-Cu changes how fibroblasts grow and what growth factors they produce, using human dermal fibroblasts, normal and irradiated, from patients previously treated with radiation for head and neck cancer, exposed to GHK-Cu at 1 x 10(-9) mol/L ^[8]. Both normal and irradiated fibroblasts treated with GHK-Cu doubled faster than untreated controls, and irradiated fibroblasts treated with GHK-Cu produced significantly more basic fibroblast growth factor and vascular endothelial growth factor than untreated controls early after exposure ^[8].

Not every study in this group found an effect. A 2013 study applied a topical GHK-Cu gel or an aquaphilic ointment control twice daily for 10 days to irradiated dorsal skin flaps in Sprague-Dawley rats, then stained the harvested tissue for a vascular-endothelium marker, caveolin-1, and for vascular endothelial growth factor ^[9]. By digital analysis, the GHK-Cu group showed a larger mean ischemic area than the control, 5.0 cm² against 3.8 cm² (P=.011), and there was no significant difference between the groups in blood-vessel number, vessel area or VEGF expression: the authors conclude that the treated flaps showed no difference in flap ischemia, blood-vessel number or area, or VEGF expression compared with controls ^[9].

A 2023 study asked whether GHK-Cu behaves differently alongside another common skincare ingredient, hyaluronic acid, HA, by treating cultured human dermal fibroblasts with a series of GHK-Cu and HA combinations and measuring collagen I, IV and VII expression ^[10]. The combination promoted the generation of all three, with a particular synergy on collagen IV: at a ratio of 1:9, GHK-Cu and low-molecular-weight HA raised collagen IV synthesis 25.4 times in the cell test and 2.03 times in a follow-up ex-vivo skin model ^[10].

How much of this reaches the skin at all is a separate question from what it does once there. A 2011 in vitro study applied copper as GHK-Cu to isolated human stratum corneum, epidermis and dermatomed skin, using flow-through diffusion cells over 48 hours ^[11]. Through dermatomed skin, the permeability coefficient was 2.43 ± 0.51 × 10⁻⁴ cm/h; 136.2 ± 17.5 μg of copper permeated each square centimetre over 48 hours, and 97 ± 6.6 μg/cm² was retained as a depot ^[11]. A 2025 review summarises the same study as retaining 0.6% to 2.8% of the applied dose across the three skin layers, and notes that GHK-Cu is fairly hydrophilic with limited permeation through the stratum corneum, prompting interest in liposome encapsulation to improve it ^[12].

Three kinds of study in this guide applied GHK-Cu to people rather than to cell cultures or animals: a randomised controlled trial in diabetic ulcers, a set of facial and cosmetic studies described in a review, and a newly registered trial in acute wounds ^[13], ^[1], ^[14].

The oldest and most rigorously designed is a 1994 multicentre, randomised, evaluator-blinded, placebo-controlled trial of a glycyl-L-histidyl-L-lysine:copper complex gel in diabetic neuropathic plantar ulcers ^[13]. Every patient followed the same aggressive standardised wound-care protocol: sharp debridement at study entry, a daily metered dose of the study drug or its vehicle, standardised pressure-relieving footwear, and education on diabetes control and activity ^[13]. Treatment significantly increased the percentage closure of plantar ulcers, a median of 98.5% of the area closed against 60.8% with vehicle, and increased the proportion of patients healing 98% or more; the rate of closure was three times faster with the gel than with standard care and vehicle alone ^[13]. The enhancement was more pronounced in the larger ulcers, those over 100 mm² at study entry, which had failed to respond adequately to standardised wound care without the gel: median closure there was 89.2% against -10.3% with vehicle, meaning the vehicle-treated larger ulcers grew rather than healed over the study period ^[13]. Treatment had to begin immediately after the initial debridement to obtain that enhancement, and the incidence of ulcer infection was significantly lower in the gel-treated ulcers, 7% against 34% with vehicle ^[13].

A separate set of findings comes from a 2015 review's own account of placebo-controlled clinical studies of skin quality in women around 50 years old, rather than from those studies' own papers, since none of them appear as a primary source in this guide's evidence ^[1]. The review describes a one-month thigh study of collagen production by skin-biopsy immunohistology, where increases were seen in 70% of women on GHK-Cu against 50% on a vitamin C cream and 40% on retinoic acid, and three further 12-week facial or eye-cream studies, in 71, 41 and 67 women respectively, each reporting reduced lines and wrinkles and increased skin density and thickness; the review names a comparator only for the 41-woman eye-cream study, a placebo control and a vitamin K eye cream, and opens by calling the group of studies placebo-controlled without naming one for the other two ^[1]. The table below sets out each study's population, duration and reported result.

The newest and only currently active human study is a Phase 2 trial registered in 2026: a randomised, double-blind, vehicle-controlled, split-wound design testing whether a topical GHK-Cu gel speeds the re-epithelialisation of small, standardised acute skin wounds in healthy adults, against a matching vehicle gel ^[14]. Each of an estimated 60 participants will receive two 5-mm punch-biopsy wounds on the non-dominant upper arm, created under local anaesthetic, with each wound randomised 1:1 to GHK-Cu gel or vehicle gel and dressed identically so the two wounds on the same arm can be compared directly ^[14]. The gel is applied once daily for 14 days under standardised non-adherent dressings, with in-clinic assessment and standardised digital photography on days 3, 7, 10, 14 and 21, and a scar assessment at week 12 ^[14]. The primary outcome is the time to complete re-epithelialisation, defined as 100% epithelial coverage without drainage, confirmed by blinded clinical assessment and photography, over a 21-day time frame, and the trial's masking is quadruple, covering participants, care providers, investigators and outcomes assessors ^[14]. As of the registration's status verification in February 2026, the trial is listed as recruiting ^[14].

The sources behind this guide report few adverse findings directly. The 1994 ulcer trial's abstract reports a lower incidence of ulcer infection with GHK-Cu gel than with vehicle, 7% against 34% ^[13]. The 2013 irradiated-rat study found no significant difference in blood-vessel number or VEGF expression between the GHK-Cu and control groups, alongside a larger mean ischemic area with GHK-Cu than with control, a difference the study's own authors report without attributing it to a specific adverse mechanism ^[9]. A 2018 review states that GHK has been used in anti-ageing and cosmetic products in humans for decades ^[2]. None of the sources report a dedicated safety trial of GHK-Cu of the kind a drug development programme would normally run.

GHK-Cu for injectable routes of administration was previously in category 2 of the FDA's interim compounding policies, the category for bulk drug substances that may present significant safety risks, and it now sits on the list of substances nominated but withdrawn, because the nominator withdrew it; the FDA's note against it says compounded injectable drugs containing GHK-Cu may pose a risk for immunogenicity due to the potential for aggregation and peptide-related impurities, and that there are limited data in humans to inform safety-related considerations ^[15]. That entry concerns injectable routes only, and the page is stated as current as of 22 April 2026 ^[15].

No source in this guide records a marketing authorisation for GHK-Cu as a medicine in the UK, the EU or the United States, and none of the sources here are a UK or EU regulator document; the only regulator sources are a US FDA compounding page and a ClinicalTrials.gov registration for the recruiting 2026 gel trial, the one registered trial in people ^[14], ^[15].

Most of what this guide describes was measured in cells or animals: fibroblast cultures, rat wound chambers, irradiated rat skin flaps and lung-tissue gene-expression panels ^[3], ^[5], ^[6], ^[7], ^[8], ^[9], ^[10]. The clearest human intervention study, the 1994 diabetic ulcer trial, is three decades old, and its result sits alongside a single newly registered trial that has not yet reported ^[13], ^[14].

The facial and cosmetic studies most often mentioned for GHK-Cu are known to this guide only through a 2015 review's own description of them, not from their own published papers, which are not among this guide's sources; a reader who wants their full methods has to go to the primary papers the review itself cites ^[1].

Only one human trial of GHK-Cu is currently active in this guide's evidence, the 2026 split-wound Phase 2 study, and its registration listed it as recruiting as of February 2026, with an estimated 60 participants and no published result yet ^[14].

How much of a topically applied GHK-Cu reaches deeper skin also remains only partly measured: the 2011 study measured a single formulation on isolated skin from cadavers, and a 2025 review notes that the transport of GHK-Cu encapsulated in liposomes, a delivery route meant to improve on that, has received little attention in the literature so far ^[11], ^[12].