Copper peptide GHK-Cu is a naturally occurring copper complex of a glycyl-L-histidyl-L-lysine peptide. Since it has three amino acids it is called tripeptide. The GHK-Cu tripeptide has strong affinity for copper(II) and was first isolated from human plasma. It can be found also in saliva and urine.
Overview
The copper peptide GHK-Cu is a naturally occurring human tripeptide. In plasma, the level of GHK-Cu is about 200 ng/ml at age 20. By the age of 60, the level drops to 80 ng/ml. Scientific studies conducted in different research laboratories around the world have established that human tripeptide GHK-Cu possesses a plethora of biological actions including activation of wound healing, attraction of immune cells, antioxidant and anti-inflammatory effects, stimulation of collagen and glycosaminoglycan synthesis in skin fibroblasts and promotion of blood vessels growth. Recent studies indicate its important role in stem cell biology and anti-tumor defense. Since GHK-Cu plays an important role in skin biology, it is widely used in cosmetics as a reparative and anti-aging ingredient.[2]
[edit]History
Copper peptide GHK-Cu was isolated from human plasma albumin in 1973 by Loren Pickart.[3] Pickart noticed that liver tissue obtained from patients aged 60 to 80 years had an increased level of fibrinogen. However, when liver cells from old patients were incubated in the blood from the younger group, the older cells started functioning in nearly the same way as the younger liver tissue.[4][5] It turned out that this effect was due to a small peptide factor that behaved similarly to the synthetic peptide glycyl-L-histidyl-L-lysine (GHK). Pickart proposed that this activity in human plasma albumin was a tripeptide glycyl-L-histidyl-L-lysine and that it might function by chelating metal ions.
In 1977, David Schlesinger of the Harvard University Chemistry Department confirmed that the growth modulating peptide isolated by Pickart was a glycyl-L-histidyl-L-lysine peptide.[7]
Further research established that GHK peptide has a strong affinity for copper and exists in two forms ***8211; GHK and GHK-Cu. On the basis of the available data, Pickart proposed that GHK-Cu functions by modulating copper intake into cells.
Wound healing
Biochemical studies
In the late 1980s, copper peptide GHK-Cu started attracting attention as a promising wound healing agent. Pioneers in this field were J.P Borel and F. Maquart from Université de Reims Champagne-Ardenne (France). Between 1988 and 2000, they found that GHK-Cu stimulated the synthesis of collagen in the skin fibroblasts, increased accumulation of total proteins, glycosaminoglycans and DNA in the dermal wounds in rats. They also found out that the GHK sequence is present in collagen and suggested that the GHK peptide is released after tissue injury. [9] [10] They proposed a class of an emegency response molecules called matrikines, which are released from the extracellular matrix at the site of an injury [11]. GHK-Cu also increased synthesis of decorin ***8211; a small proteoglycan involved in the regulation of collagen synthesis, wound healing regulation and anti-tumor defense.[12]
The same group established that GHK-Cu stimulated both the synthesis of metalloproteinases, the enzymes which break down dermal proteins, and their inhibitors (anti-proteases). The fact that GHK-Cu not only stimulates the production of dermal components, but also regulates their breakdown suggests its regulatory role in the skin remodeling process.
Wound healing in animals
A series of animal experiments established pronounced wound healing activity of copper peptide GHK-Cu. In the dermal wounds of rabbits GHK-Cu facilitated wound healing, causing better wound contraction, faster development of granular tissue and improved angiogenesis. It also elevated the level of antioxidant enzymes.[14] [15]
GHK-Cu has been found to induce a systemic enhancement of healing in rats, mice, and pigs; that is, the GHK-Cu peptide injected in one area of the body (such as the thigh muscles) improved healing at distant body areas (such as the ears). These treatments strongly increased healing parameters such as collagen production, angiogenesis, and wound closure in both wound chambers and full thickness wounds.[16]
Biotinylated GHK-Cu was incorporated into a collagen membrane, which was used as a wound dressing. This GHK-Cu enriched material stimulated wound contraction and cell proliferation, as well as increased expression of antioxidant enzymes. The same material was tested for wound healing in diabetic rats. GHK-Cu treatment resulted in faster wound contraction and epithelization, higher level of glutathione and ascorbic acid, increased synthesis of collagen, and activation of fibroblasts and mast cells.[17] Ischemic open wounds in rats treated with GHK-copper healed faster and had decreased concentration of metalloproteinases 2 and 9 as well as of TNF-beta (a major inflammatory cytokine) compared with vehicle alone or with untreated wounds.[18]
Human trials
A 2% GHK gel showed promising results in treatment of 120 diabetic patients, increasing the percentage of ulcer closure from 60.8% to 98.5%, and decreasing the percentage of infection from 34% to 7%. The rate of healing was three times greater with GHK.[19] However, a 0.4% GHK-Cu cream failed to reach therapeutic goal in treatment of venous ulcers.[20] It is possible that that failure was due to a presence of bacterial film on hospital wounds that led to a fast degradation of the peptide. Recently, a second generation of breakdown resistant copper peptides was developed.[21]
Current research
DNA repair
Radioactive anti-cancer treatment slows cell replication by breaking DNA strands. A recent study showed GHK-Cu's ability to restore function of irradiated fibroblasts to that of intact cells. The researchers used cultured human fibroblasts obtained from cervical skin that was either intact or exposed to radioactive treatment (5000 rad). At a very low (1 nanomolar) concentration, GHK-Cu stimulated irradiated fibroblasts growth and increased their production of growth factors bFGF and VGF to the point where it became even higher than that of both the irradiated and intact control cells.[22]
Nerve regeneration
In 2005, Ahmed et al. demonstrated that GHK promotes nerve regeneration. Axon regeneration was studied using collagen tubes with incorporated peptides. GHK increased migration of hematogenous cells into collagen tube, production of nerve growth factors, expression of integrins and the rate of regeneration of myelinated nerve fibers. In addition, GHK also increased axon count and proliferation of Schwann cells compared to the control.[23]
Effect on stem cells
In 2009, a group of researchers from the Seoul National University (Republic of Korea) demonstrated that the copper-peptide GHK-Cu stimulated proliferation of keratinocytes and increased expression of integrins and p63 protein in the epidermal stem cells. Since p63 is considered to be an important marker of stem cell and anti-senescence protein, the authors concluded that GHK-copper is able to revive the proliferative potential of epidermal stem cells and increase their ability to repair tissue.[24]
Anti-cancer effect
In 2010, Hong Y. et al. demonstrated that GHK-Cu is able to reverse the expression of certain genes involved in metastatic spreading of colon cancer. GHK-Cu was effective at a very low concentration - 1mkM.[25]
Genomic studies
Recent genomic research suggests that GHK directly modulates gene expression, which may explain the diversity of its biological actions. Iorio et al. used a repository of transcriptional responses to compounds, the Connectivity Map (cMap)[26], and MANTRA software to explore networks of compounds producing similar transcriptional responses. GHK, as one of the compounds studied, increased mRNA production in 268 genes while suppressing 167.[27]
[edit]Cosmetic use
Facial studies
Copper peptide GHK-Cu is widely used in anti-aging cosmetics (INCI name: Copper tripeptide-1).[28] Several controlled facial studies confirmed anti-aging, firming and anti-wrinkle activity of copper peptide GHK-Cu.
Abdulghani et al. established that facial cream containing GHK-Cu increased collagen in photoaged skin of 20 female volunteers, performing better than vitamin C and retinoic acid.[29]
Leyden et al. conducted a 12-week facial study of GHK-Cu containing face and eye cream, reporting significant improvement of skin laxity, clarity and appearance, reduced fine lines and the depths of wrinkles and increased skin density and thickness comparing to placebo. GHK-Cu eye cream performed better than vitamin K cream.[30]
Finkley et al. conducted 12 week facial study on 67 women and reported that GHK-Cu cream applied twice daily improved aged skin appearance, increased thickness, reduced wrinkles and strongly stimulated dermal keratinocyte proliferation as determined by histological analysis of biopsies. The same study found copper peptide GHK-Cu to be non-toxic and non-irritating.[31]
Hair growth
Copper peptide GHK-Cu and its analogues were found to strongly stimulate hair growth. The efficiency of synthetic analog of GHK-Cu was similar to that of 5% minoxidil.[32] A commercial product GraftCyte was clinically proven to improve hair transplantation,[33] outcome. Another hair product that contains copper-peptide GHK-Cu is Tricomin.
Biological chemistry
Copper binding
Research of the copper binding properties of GHK and two synthetic peptides, in which histidine was replaced with a synthetic amino acid, established that the amino acid glycine plays major role in copper binding, while lysine can interact with copper only at alkaline pH. At physiological pH, lysine is able to interact with a cellular receptor. The ability of GHK to interact both with copper and with a cellular receptor allows it to transfer copper into and from cells. The small size of GHK permits speedy traveling in extracellular space and its easy access to cellular receptors.
Biological significance
Copper is a transitional metal that is vital for all eukaryotic organisms from microbes to humans. A dozen enzymes (cuproenzymes) use changes in copper oxidation state to catalyze important biochemical reactions including cellular respiration (cytochrome c oxidase), antioxidant defense (ceruloplasmin, superoxide dismutase (SOD), detoxification (metallothioneins), blood clotting (blood clotting factors V and VIII), melanin production (tyrosinase) and the connective tissue formation (lysyl peroxidase). Copper is required for iron metabolism, oxygenation, neurotransmission, embryonic development and many other essential biological processes. Another function of copper is signaling ***8211; for example, stem cells require a certain level of copper in the media to start their differentiation into cells needed for repair. Thus, GHK-Cu***8217;s ability to bind copper and to modulate its tissue level is a key factor determining its biological activity.[36]
Overview
The copper peptide GHK-Cu is a naturally occurring human tripeptide. In plasma, the level of GHK-Cu is about 200 ng/ml at age 20. By the age of 60, the level drops to 80 ng/ml. Scientific studies conducted in different research laboratories around the world have established that human tripeptide GHK-Cu possesses a plethora of biological actions including activation of wound healing, attraction of immune cells, antioxidant and anti-inflammatory effects, stimulation of collagen and glycosaminoglycan synthesis in skin fibroblasts and promotion of blood vessels growth. Recent studies indicate its important role in stem cell biology and anti-tumor defense. Since GHK-Cu plays an important role in skin biology, it is widely used in cosmetics as a reparative and anti-aging ingredient.[2]
[edit]History
Copper peptide GHK-Cu was isolated from human plasma albumin in 1973 by Loren Pickart.[3] Pickart noticed that liver tissue obtained from patients aged 60 to 80 years had an increased level of fibrinogen. However, when liver cells from old patients were incubated in the blood from the younger group, the older cells started functioning in nearly the same way as the younger liver tissue.[4][5] It turned out that this effect was due to a small peptide factor that behaved similarly to the synthetic peptide glycyl-L-histidyl-L-lysine (GHK). Pickart proposed that this activity in human plasma albumin was a tripeptide glycyl-L-histidyl-L-lysine and that it might function by chelating metal ions.
In 1977, David Schlesinger of the Harvard University Chemistry Department confirmed that the growth modulating peptide isolated by Pickart was a glycyl-L-histidyl-L-lysine peptide.[7]
Further research established that GHK peptide has a strong affinity for copper and exists in two forms ***8211; GHK and GHK-Cu. On the basis of the available data, Pickart proposed that GHK-Cu functions by modulating copper intake into cells.
Wound healing
Biochemical studies
In the late 1980s, copper peptide GHK-Cu started attracting attention as a promising wound healing agent. Pioneers in this field were J.P Borel and F. Maquart from Université de Reims Champagne-Ardenne (France). Between 1988 and 2000, they found that GHK-Cu stimulated the synthesis of collagen in the skin fibroblasts, increased accumulation of total proteins, glycosaminoglycans and DNA in the dermal wounds in rats. They also found out that the GHK sequence is present in collagen and suggested that the GHK peptide is released after tissue injury. [9] [10] They proposed a class of an emegency response molecules called matrikines, which are released from the extracellular matrix at the site of an injury [11]. GHK-Cu also increased synthesis of decorin ***8211; a small proteoglycan involved in the regulation of collagen synthesis, wound healing regulation and anti-tumor defense.[12]
The same group established that GHK-Cu stimulated both the synthesis of metalloproteinases, the enzymes which break down dermal proteins, and their inhibitors (anti-proteases). The fact that GHK-Cu not only stimulates the production of dermal components, but also regulates their breakdown suggests its regulatory role in the skin remodeling process.
Wound healing in animals
A series of animal experiments established pronounced wound healing activity of copper peptide GHK-Cu. In the dermal wounds of rabbits GHK-Cu facilitated wound healing, causing better wound contraction, faster development of granular tissue and improved angiogenesis. It also elevated the level of antioxidant enzymes.[14] [15]
GHK-Cu has been found to induce a systemic enhancement of healing in rats, mice, and pigs; that is, the GHK-Cu peptide injected in one area of the body (such as the thigh muscles) improved healing at distant body areas (such as the ears). These treatments strongly increased healing parameters such as collagen production, angiogenesis, and wound closure in both wound chambers and full thickness wounds.[16]
Biotinylated GHK-Cu was incorporated into a collagen membrane, which was used as a wound dressing. This GHK-Cu enriched material stimulated wound contraction and cell proliferation, as well as increased expression of antioxidant enzymes. The same material was tested for wound healing in diabetic rats. GHK-Cu treatment resulted in faster wound contraction and epithelization, higher level of glutathione and ascorbic acid, increased synthesis of collagen, and activation of fibroblasts and mast cells.[17] Ischemic open wounds in rats treated with GHK-copper healed faster and had decreased concentration of metalloproteinases 2 and 9 as well as of TNF-beta (a major inflammatory cytokine) compared with vehicle alone or with untreated wounds.[18]
Human trials
A 2% GHK gel showed promising results in treatment of 120 diabetic patients, increasing the percentage of ulcer closure from 60.8% to 98.5%, and decreasing the percentage of infection from 34% to 7%. The rate of healing was three times greater with GHK.[19] However, a 0.4% GHK-Cu cream failed to reach therapeutic goal in treatment of venous ulcers.[20] It is possible that that failure was due to a presence of bacterial film on hospital wounds that led to a fast degradation of the peptide. Recently, a second generation of breakdown resistant copper peptides was developed.[21]
Current research
DNA repair
Radioactive anti-cancer treatment slows cell replication by breaking DNA strands. A recent study showed GHK-Cu's ability to restore function of irradiated fibroblasts to that of intact cells. The researchers used cultured human fibroblasts obtained from cervical skin that was either intact or exposed to radioactive treatment (5000 rad). At a very low (1 nanomolar) concentration, GHK-Cu stimulated irradiated fibroblasts growth and increased their production of growth factors bFGF and VGF to the point where it became even higher than that of both the irradiated and intact control cells.[22]
Nerve regeneration
In 2005, Ahmed et al. demonstrated that GHK promotes nerve regeneration. Axon regeneration was studied using collagen tubes with incorporated peptides. GHK increased migration of hematogenous cells into collagen tube, production of nerve growth factors, expression of integrins and the rate of regeneration of myelinated nerve fibers. In addition, GHK also increased axon count and proliferation of Schwann cells compared to the control.[23]
Effect on stem cells
In 2009, a group of researchers from the Seoul National University (Republic of Korea) demonstrated that the copper-peptide GHK-Cu stimulated proliferation of keratinocytes and increased expression of integrins and p63 protein in the epidermal stem cells. Since p63 is considered to be an important marker of stem cell and anti-senescence protein, the authors concluded that GHK-copper is able to revive the proliferative potential of epidermal stem cells and increase their ability to repair tissue.[24]
Anti-cancer effect
In 2010, Hong Y. et al. demonstrated that GHK-Cu is able to reverse the expression of certain genes involved in metastatic spreading of colon cancer. GHK-Cu was effective at a very low concentration - 1mkM.[25]
Genomic studies
Recent genomic research suggests that GHK directly modulates gene expression, which may explain the diversity of its biological actions. Iorio et al. used a repository of transcriptional responses to compounds, the Connectivity Map (cMap)[26], and MANTRA software to explore networks of compounds producing similar transcriptional responses. GHK, as one of the compounds studied, increased mRNA production in 268 genes while suppressing 167.[27]
[edit]Cosmetic use
Facial studies
Copper peptide GHK-Cu is widely used in anti-aging cosmetics (INCI name: Copper tripeptide-1).[28] Several controlled facial studies confirmed anti-aging, firming and anti-wrinkle activity of copper peptide GHK-Cu.
Abdulghani et al. established that facial cream containing GHK-Cu increased collagen in photoaged skin of 20 female volunteers, performing better than vitamin C and retinoic acid.[29]
Leyden et al. conducted a 12-week facial study of GHK-Cu containing face and eye cream, reporting significant improvement of skin laxity, clarity and appearance, reduced fine lines and the depths of wrinkles and increased skin density and thickness comparing to placebo. GHK-Cu eye cream performed better than vitamin K cream.[30]
Finkley et al. conducted 12 week facial study on 67 women and reported that GHK-Cu cream applied twice daily improved aged skin appearance, increased thickness, reduced wrinkles and strongly stimulated dermal keratinocyte proliferation as determined by histological analysis of biopsies. The same study found copper peptide GHK-Cu to be non-toxic and non-irritating.[31]
Hair growth
Copper peptide GHK-Cu and its analogues were found to strongly stimulate hair growth. The efficiency of synthetic analog of GHK-Cu was similar to that of 5% minoxidil.[32] A commercial product GraftCyte was clinically proven to improve hair transplantation,[33] outcome. Another hair product that contains copper-peptide GHK-Cu is Tricomin.
Biological chemistry
Copper binding
Research of the copper binding properties of GHK and two synthetic peptides, in which histidine was replaced with a synthetic amino acid, established that the amino acid glycine plays major role in copper binding, while lysine can interact with copper only at alkaline pH. At physiological pH, lysine is able to interact with a cellular receptor. The ability of GHK to interact both with copper and with a cellular receptor allows it to transfer copper into and from cells. The small size of GHK permits speedy traveling in extracellular space and its easy access to cellular receptors.
Biological significance
Copper is a transitional metal that is vital for all eukaryotic organisms from microbes to humans. A dozen enzymes (cuproenzymes) use changes in copper oxidation state to catalyze important biochemical reactions including cellular respiration (cytochrome c oxidase), antioxidant defense (ceruloplasmin, superoxide dismutase (SOD), detoxification (metallothioneins), blood clotting (blood clotting factors V and VIII), melanin production (tyrosinase) and the connective tissue formation (lysyl peroxidase). Copper is required for iron metabolism, oxygenation, neurotransmission, embryonic development and many other essential biological processes. Another function of copper is signaling ***8211; for example, stem cells require a certain level of copper in the media to start their differentiation into cells needed for repair. Thus, GHK-Cu***8217;s ability to bind copper and to modulate its tissue level is a key factor determining its biological activity.[36]
