GHK-Cu Peptide: molecular mechanisms, wound healing, skin research and experimental results

GHK-Cu is a copper-binding complex formed from the naturally occurring tripeptide glycyl-L-histidyl-L-lysine (GHK) and copper ion. GHK consists of three amino acids: glycine, histidine, and lysine. It was identified in human plasma in 1973. The presence of this peptide was also described in other body fluids, including saliva and urine. Early studies linked GHK to changes in protein production in aging liver tissue, which initiated interest in its possible role in tissue maintenance and repair.

Since then, scientists have studied GHK and its copper complex in the context of skin biology, wound healing, inflammation, oxidative stress, and other experimental processes. The peptide’s ability to coordinate copper ions is of particular importance, as copper is involved in the activity of many enzymes and cellular processes. However, the mere binding of copper, changes in laboratory biomarkers, or improvements in animal models do not constitute evidence of clinical benefits in humans.

GHK-Cu also appears in cosmetic studies, particularly those concerning the appearance of the skin and formulations related to hair care. Other proposed applications, including in neurological and pulmonary diseases, remain at a much earlier stage of research. This review presents the individual studies, the biological pathways analyzed, and the limitations resulting from the conclusions.

GHK-Cu and tissue repair: wound healing and extracellular matrix reconstruction

Recruitment of repair cells and regulation of inflammatory signals

In a 2008 review, Pickart discussed the role of GHK in tissue remodeling, including the attraction of macrophages and fibroblast-related cells to injury sites [1]. These cells are involved in the removal of damaged components, vascular responses, and tissue repair. The review also described the effects on collagen, elastin, and other structural proteins responsible for maintaining the extracellular matrix.

The proposed mechanisms include changes in the activity of vascular endothelial growth factor (VEGF), nerve growth factor, and related signals associated with angiogenesis and tissue organization. The effect of GHK-Cu on oxidative processes, including superoxide dismutase activity, and on local vascular responses was also studied.

These interconnected mechanisms provide the biological rationale for the interest in the peptide. However, much of the observations come from cell culture or animal experiments, rather than from conclusive clinical studies [1].

Proliferation of keratinocytes, integrin and p63 protein

Kang and colleagues studied the GHK complex with copper in laboratory experiments involving keratinocytes, which are cells that form a significant portion of the outer protective layer of the skin [2].

Increased cell proliferation and changes in proteins related to adhesion and cell renewal were observed. In particular, researchers described an increase in the expression of integrins, the nuclear antigen of proliferating cells (PCNA), and p63, a marker important for the epithelial cell population.

Histological staining, immunohistochemistry and the Western blot method were used to evaluate these reactions, among other things.

Overall, the results suggest that the GHK complex with copper can influence cellular processes important for epidermal regeneration. However, they do not prove that every product applied topically causes the same response in undamaged human skin [2].

Liposomal GHK-Cu in vascular cells and in a burn model in mice

One study evaluated GHK-Cu encapsulated in liposomes of nanometer size, using vascular cell cultures and a model of thermal burns in mice [3].

In human umbilical vein endothelial cells (HUVECs), the liposomal preparation bound with a 33.1% increase in cell proliferation.

The results of flow cytometry indicated a change in the phase distribution of the cell cycle: an increase in the percentage of cells in the G1 phase and a decrease in the G2 phase.

The researchers also noted higher levels of VEGF, fibroblast growth factor 2 (FGF-2), CDK4, and cyclin D1. These results were consistent with changes in signaling responsible for the development of blood vessels and the regulation of the cell cycle.

In burn experiments in mice, the liposomal formulation was associated with stronger staining of the CD31 and Ki67 markers and more intense angiogenic responses than free GHK-Cu.

Wound healing was described around the 14th day after injury.

The results are important for formulation research because delivery systems can change the way substances reach tissues. However, the results obtained for liposomes cannot be automatically transferred to other products containing GHK-Cu [3,4].

Collagen, glycosaminoglycans and the accumulation of connective tissue components

In experiments on rats and in cultures of rat skin fibroblasts, it was evaluated whether GHK-Cu affects the composition of newly formed tissue within the wounds [5].

In animal experiments, multiple injections of 2 mg per administration were described.

In treated wounds, greater dry tissue mass and total protein content were observed, as well as an increase in type I collagen and parameters related to glycosaminoglycans, such as hydroxyproline and uric acid.

The researchers also observed changes in the individual components of the matrix. In the wound tissue, the amount of chondroitin sulfate and dermatan sulfate increased, while the content of hyaluronic acid decreased during the observation period.

The results suggest a selective regulation of the synthesis of extracellular matrix, but not the equal growth of all its components [5].

In a broader review, changes associated with GHK in fibroblasts exposed to radiation, the recruitment of immune and epithelial cells, and their possible significance for the skin, hair follicles, and tissues of the gastrointestinal tract were discussed [6].

Cosmetic endpoints were also analyzed, such as skin texture, elasticity, fine wrinkles, and visible signs of photoaging.

These are, however, separate categories of evidence. Laboratory reactions help explain the mechanisms, whereas cosmetic results in humans require properly controlled studies of finished preparations.

GHK-Cu in experimental lung research

Pulmonary fibrosis caused by bleomycin

In several studies, GHK or GHK-Cu were analyzed in mouse models of lung fibrosis.

In one of the experiments, Ma and colleagues evaluated GHK-Cu after pulmonary damage caused by bleomycin [7].

In animals receiving the compound under study, a reduction in inflammatory signals, oxidative stress, collagen accumulation, and biochemical features associated with fibrosis were observed.

The researchers also analyzed changes in the activity of enzymes and regulatory pathways affecting the remodeling of the extracellular matrix and the maintenance of epithelial cells.

In a related study in mice, GHK was analyzed in a model of pulmonary fibrosis induced by bleomycin, focusing on the TGF-β1/Smad pathway [8].

Smaller thickening of the interstitial tissue was observed, a reduction in collagen deposition, and lower levels of inflammatory markers and fibrosis.

The results also indicated a slowdown in the epithelial-mesenchymal transition, a process in which epithelial cells acquire characteristics related to tissue remodeling.

Although these observations indicate biologically plausible mechanisms, the pulmonary damage caused by bleomycin in mice is not equivalent to idiopathic scarring of the lungs in patients [7,8].

Severe lung damage and inflammatory signaling

Park and colleagues studied GHK-Cu in a model of acute lung injury caused by lipopolysaccharide (LPS) [9].

In cell experiments, exposure to the complex was associated with lower levels of reactive oxygen species (ROS), greater activity of superoxide dismutase (SOD), and reduced production of inflammatory cytokines.

In experiments on mice, smaller tissue damage and a weaker inflammatory response were also described after the experimental injury was caused.

These observations justify further research into oxidative and inflammatory pathways in acute lung injury.

However, they do not prove that GHK-Cu cures acute respiratory distress syndrome (ARDS) in humans, whose clinical course is much more complex [9].

Cigarette smoke, emphysema and muscle dysfunction

In a 12-week exposure model in mice to cigarette smoke, it was evaluated whether GHK-Cu alters lung damage-related characteristics [10].

The study noted lower structural damage to the lungs, lower levels of inflammatory cytokines and markers of oxidative stress, and a more favorable balance between enzymes that break down tissue and their inhibitors.

Additional experiments on human lung cells confirmed the possibility of the occurrence of antioxidant activity under laboratory conditions.

Separate studies concerned disorders of skeletal muscle function associated with exposure to cigarette smoke [11].

In the examined cells and in mice, GHK-Cu was associated with lower levels of muscle degradation and changes in the pathways responsible for antioxidant defense.

Researchers pointed to the role of sirtuin 1 (SIRT1), a protein involved in the cellular response to stress.

The results suggest a research link between muscle damage caused by smoke and SIRT1-dependent signaling. However, they do not provide evidence of the efficacy of GHK-Cu in the treatment of muscle disorders in people with chronic obstructive pulmonary disease (COPD) [10,11].

Reconstruction of the respiratory tract in a model associated with asthma

In an experimental model induced by chicken albumin (owalbumin), the effect of GHK-Cu on the reconstruction of the airways was studied [12].

The results described included a reduction in mucus production, a reduction in structural changes of the airways, and a weakening of inflammatory-related signals.

As an important element of the observed response, the activation of SIRT1 in airway epithelial cells was proposed.

Because the persistent restriction of airflow in severe asthma develops through several overlapping mechanisms, the ovalbumin model only allows for a partial explanation of this process.

The study therefore provides preclinical evidence of airway signaling, rather than confirmation of improved symptoms or lung function in patients [12].

GHK-Cu and graft healing after anterior cruciate ligament reconstruction

Fu and colleagues studied GHK-Cu in 72 rats after reconstruction of the anterior cruciate ligament (ACL) [13].

The animals were assigned to groups receiving either physiological saline or GHK-Cu preparations at concentrations of 0.3 mg/ml and 3 mg/ml.

According to the described protocol, administration began in the second week after the operation and continued once a week for four weeks.

After six weeks in the GHK-Cu groups, less knee joint instability was observed than in animals receiving physiological salt. This suggested a transient difference in graft stabilization.

However, at the 12th week, the groups no longer differed significantly in terms of instability, graft stiffness, or other evaluated mechanical parameters.

The most important conclusion therefore concerns the limited temporal nature of the observations. The early improvement in this model did not translate into a lasting advantage in subsequent evaluation [13].

Cosmetic research in humans: skin surface renewal and markers of collagen

The published case report describes a 59-year-old man who was treated with a multi-component cosmetic formulation containing a GHK complex with copper, hyaluronic oligopeptide, rosehip extract, tranexamic acid, and β-glucan [14].

The preparation was delivered using the Jet-M device. Treatments were performed every week for three months.

Clinical photographs suggested changes in the texture of the skin and wrinkles around the eyes.

In the biopsy study, stronger staining of structural proteins was observed, including collagen IV, fibrin-1, procollagen type I, and tropoelastin.

No adverse reactions were reported in this patient.

However, the design of the study does not allow determining the contribution of the GHK complex itself containing copper, since several components and a device for their delivery were simultaneously used.

A single case report also does not allow to determine the overall safety or efficacy in a larger population [14].

GHK-Cu and the synthesis of glycosaminoglycans in fibroblasts

Wegrowski and colleagues studied GHK-Cu in fibroblast cultures, tracking the incorporation of radiolabeled glucosamine and sulfates into glycosaminoglycans [15].

The answer depended on the concentration.

The greatest increase was observed at concentrations of about 10⁻⁹–10⁻⁸ M, whereas higher concentrations led to results more similar to those obtained in control cells.

The changes were also selective in nature.

The amount of dermatan sulfate increased mainly in the extracellular space, while the heparan sulfate increased in the cell-bound fraction.

No changes corresponding to these changes in hyaluronic acid synthesis were observed.

The results are important because they show that GHK-Cu did not stimulate the synthesis of all glycosaminoglycans to the same extent [15].

GHK-Cu in a rat model of wound healing

Maquart and colleagues used implanted stainless steel mesh chambers to create a controlled wound healing environment under the skin of rats [16].

Physiological salt or a copper tripeptide complex was introduced into the cells.

Next, the researchers measured the dry mass of the tissue, the DNA content, the total amount of proteins, collagen, and components related to glycosaminoglycans.

Higher amounts of several connective tissue components were found in the chambers receiving GHK-Cu than in the control group.

The increase in the amount of collagen was approximately twice as great as the increase in the amount of non-collagen proteins.

The accumulation of dermatan sulfate also increased, while the level of informational RNA for TGF-β did not change in a way that could be expected based on a simple mechanism dependent on a single growth factor.

The results suggest that the deposition of matrix components can be regulated by several pathways, and not solely by a uniform increase in the activity of a single signal [16].

GHK and learning after sleep deprivation in mice

Rosenfeld and colleagues investigated whether GHK affects the learning ability in aging mice subjected to sleep deprivation [17].

Compared to control animals receiving physiological salt, group GHK showed less deterioration in the learning test results described in the study.

The researchers also noted lower levels of the chemokine monocyte 1 (MCP-1) protein and nitrotyrosine in the hippocampus.

These markers are associated with inflammatory signaling and oxidative or nitrosative stress respectively.

The study concerned GHK in a mouse model. It should not be interpreted as evidence that a product containing GHK-Cu prevents memory impairments associated with sleep deprivation in humans.

Distinguishing between the peptide itself and its copper complex is particularly important when comparing neurological studies [17].

GHK in studies of cognitive functions related to aging

In a study involving older C57BL/6 mice, GHK administered orally was evaluated for approximately two months [18].

The source material describes an experimental amount of 15 mg/kg per day.

Mice receiving GHK achieved better results in spatial learning or orientation tests than control animals.

Lower values of parameters related to neuroinflammation and axon damage were also observed.

The study was presented in the provided bibliography as a preprint published on the bioRxiv website.

Therefore, before drawing strong conclusions, the status of the publication and the methodology used must be evaluated very carefully.

The route of administration used was an experimental one in animals, and not an approved method of delivering the substance to humans or a recommended dosage [18].

GHK in models of Alzheimer's disease

In another study, researchers investigated the orally administered GHK in transgenic mice with 5xFAD, which were used to analyze selected features of Alzheimer's disease [19].

The experiment was started when the animals were about four months old.

The described protocol included 15 mg/kg three times a week for three months.

The researchers presented differences in cognitive test scores, accumulation of amyloid plaques, and inflammatory markers in the frontal cortex and hippocampus.

The results may help formulate hypotheses regarding the mechanisms of neurodegeneration, but they do not confirm the prevention of Alzheimer's disease or its treatment in humans.

The 5xFAD model only reflects selected disease characteristics, and the substance studied was GHK, not necessarily a chemically characterized formulation of GHK-Cu [19].

Studies of gene expression and oxidative stress related to copper

The review of data on gene expression discussed the possibility of GHK influencing groups of genes related to the functioning of the nervous system, cellular repair, inflammation, and aging [20].

The authors used, among other things, the Connectivity Map data to analyze the relationships between the peptide and gene expression profiles.

The computational results indicate possible pathways that require further investigation. They do not constitute clinical evidence that GHK restores the younger biological state to the aging human brain.

Other reviews discussed copper homeostasis, oxidative stress, inflammation, and epigenetic processes in the context of age-related degeneration [21].

Copper is essential for the body, but when its regulation is impaired, it can be harmful. The behavior of the copper-binding peptide therefore depends on the chemical and biological context.

Claims regarding restoring copper balance or preventing cognitive impairment require direct research, not merely inference based on antioxidant markers.

Protein aggregation caused by metals and cell damage

Min and colleagues studied GHK in laboratory systems exposed to copper or zinc, analyzing protein aggregation and damage to central nervous system cells [22].

Experiments suggested that GHK may reduce some aggregation reactions and metal-related toxicity.

The supplied material also discusses the aggregation of serum albumin and interactions involving paraquate and copper.

These are mechanistic observations obtained in vitro.

The ability to influence the behavior of proteins in a controlled experimental mixture is not equivalent to a confirmed ability to prevent neurodegenerative diseases.

Transport, metabolism, and complex tissue interactions are also important in the body [22].

Collagen matrices containing GHK in diabetic wound models

Arul and colleagues developed a collagen material containing biotinylated GHK, referred to as peptide-incorporated collagen (PIC), and evaluated it in rats with diabetes [23].

The researchers compared this material with ordinary collagen foil and wounds without treatment.

The evaluated parameters included wound closure, collagen and uric acid content, total protein content, DNA, nitric oxide, and antioxidant indicators such as glutathione and ascorbic acid.

In the PIC group, faster wound closure and more favorable antioxidant parameters were observed than in the comparison groups.

Histological studies indicated differences in fibroblast activity, collagen deposition, and wound organization.

Laboratory tests also suggested that the material promoted the growth of fibroblasts.

It should be emphasized that a complex biomaterial containing modified GHK was studied, and not free GHK-Cu, directly in humans [23].

Studies on copper trpeptide preparations in humans with diabetic foot ulcers

Mulder and colleagues investigated a local complex of glycyl-L-histidyl-L-lysine with copper, described in the source material as Iamin or Lamin gel, in patients with neuropathic diabetic ulcers [24].

Participants also received standard wound care, including cleaning, debridement, appropriate footwear, and education regarding diabetes management.

The median reduction in wound area was 98.5% in the active group and 60.8% in the placebo group, according to the source.

A smaller number of infections were also described in the treated group, and a particularly noticeable response was observed in the case of larger wounds.

These are the results of research on wound healing in humans, but their interpretation depends on the study design, the characteristics of the participants, and the primary treatment used in both groups.

They do not prove that other, unrelated formulations of GHK-Cu would have achieved comparable results [24].

In an earlier open-label pilot study, the copper-chelating GHK compound was evaluated as PC1020 in diabetic ulcers [25].

The study described locally administered preparations with concentrations of 0.03%, 0.3%, and 3.0%, compared to physiological saline over a two-week experimental period.

In the 0.3% group, there was a greater closing of wounds than in the group receiving physiological salt.

Because the study was small and preliminary in nature, the results should be considered an early clinical signal requiring confirmation, rather than a fixed treatment protocol [25].

GHK in experimental cerebral hemorrhage

In a rat model of cerebral hemorrhage, the effect of GHK on brain damage was evaluated [26].

The source material describes experimental amounts of 5 and 10 µg/g.

Researchers noted a reduced brain swelling, better neurological assessment results, greater neuron survival, and changes in inflammatory and extracellular matrix markers.

The study also indicated the involvement of the Akt/miR-146a-3p/AQP4 pathway.

This suggests a link between the signaling responsible for cell survival and the regulation of water transport after hemorrhage.

The results come from an animal model and the accompanying mechanistic studies. They do not confirm the efficacy of GHK in the treatment of hemorrhagic stroke in humans [26].

Local copper trpeptide complex in non-ischemic wounds in rats

Canapp and colleagues investigated the local copper trpeptide complex labeled as Iamin 2% in 24 male Sprague-Dawley rats with experimentally induced ischemic lesions [27].

The comparison groups received either the gel base alone or no treatment.

After 13 days, the reduction in wound area was approximately 64.5% in the active preparation group, 45.6% in the gel base group, and 28.2% in the no treatment group.

Biopsy measurements also indicated lower levels of selected inflammatory markers and markers associated with tissue degradation in treated wounds.

Including the group receiving the base of the preparation itself is important, because the carrier can also affect the healing conditions.

Nevertheless, the mouse model of ischemia does not allow the confirmation of equivalent efficacy in human wounds [27].

Recombinant GHK and copper-induced cardiotoxicity in zebrafish

Hsiao and colleagues obtained recombinant tripeptides related to GHK and studied their interactions with copper in the larvae of the striped bream [28].

In larvae exposed to copper present in the water, peptide preparations were associated with less bradycardia and less frequent irregular heartbeats.

The study described activity at concentrations as low as 1 nM, without comparable changes in other cardiovascular parameters evaluated.

The researchers interpreted the results in the context of copper binding and protection against toxicity associated with its presence.

This is an experimental toxicological observation in a small aquatic organism model, and not evidence that GHK-Cu protects the human heart against common cardiovascular diseases [28].

Human hair studies: the combination of 5-ALA and GHK

Lee and colleagues evaluated the formulation combining 5-aminolevulinic acid (5-ALA) and GHK, referred to as ALAVAX, in 45 men with androgenic alopecia [29].

The study lasted six months and compared different concentrations of the drug with a placebo.

According to the source, a significant improvement in the number of hair was observed in the group receiving the medium-concentration preparation, defined as 50 mg/ml, compared to the higher-concentration group and placebo.

Participants also reported satisfaction with the intervention used, although the length and thickness of the hair did not differ significantly between the groups.

No adverse reactions were reported in the study.

Since the test preparation contained both 5-ALA and GHK, the contribution of GHK alone cannot be determined.

The results should also not be presented as evidence regarding GHK-Cu [29] alone.

GHK-Cu in cosmetic skin studies: evidence in humans and its limitations

A 2018 review summarized the research on GHK-Cu and cosmetic indicators of skin aging [30].

In one of the cited studies, 71 women who used a face cream for 12 weeks were observed. Changes in skin density and thickness, its firmness, clarity, and fine wrinkles were described.

Another study, involving 41 women, examined an eye cream used for 12 weeks.

An improvement in the appearance of wrinkles and skin density parameters was observed compared to the selected comparator products.

The review also discussed a study of collagen production in the thigh skin, in which about 70% women using the GHK-Cu preparation showed an increase in collagen-related parameters.

Studies on skin firmness, hydration and elasticity were also presented.

In a separate eight-week study with the nanolipid carrier formulation, a reduction in the volume and depth of wrinkles was described compared to the control serum and Matrixyl 3000 product.

The results are important for research into cosmetic formulations, but they do require taking into account several limitations.

The review combines studies using different preparations, comparison groups, populations, and measurement methods.

The positive result obtained for the finished cream cannot be attributed entirely to GHK-Cu without an appropriate controlled study.

Similarly, improvements in wrinkle parameters or skin thickness do not confirm an overall anti-aging effect [30].

Conclusions: what do the available evidence confirm?

GHK and GHK-Cu were studied in many different experimental systems.

The most frequently recurring mechanisms involve remodeling of the extracellular matrix, processes related to collagen, activity of keratinocytes and fibroblasts, angiogenesis, and inflammatory and oxidative signaling.

In small studies involving humans, specific topical preparations for chronic wounds and cosmetic applications for the skin were also evaluated.

Other areas, such as pulmonary fibrosis, diabetic neuropathy, hemorrhagic brain injury, models of Alzheimer's disease, and copper toxicity related to cardiac function, rely primarily on cellular or animal studies.

Some of the neurological studies cited in the source are in the preprint status, and in several experiments GHK was used without confirmation that the substance under study is equivalent to GHK-Cu.

Multicomponent preparations, liposomal carriers and modified peptides introduce additional differences that should not be overlooked.

Overall, the studies provide valuable hypotheses regarding the biology of copper-binding peptides.

However, the wide range of mechanisms studied should not be equated with equally strong clinical evidence for all proposed uses.

Before translating many experimental results into established clinical conclusions, larger, well-controlled studies involving humans, more accurate formulation characterization, and evaluation of long-term safety are necessary.

Scientific and editorial note: The article presents the published and preliminary results of the research for educational purposes only. Experimental concentrations, doses used in animals, and routes of administration are described as elements of original research, and not as instructions for use in humans. The bibliography derived from the source material has not been independently verified.

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