Mechanism of action
GHK (glycyl-L-histidyl-L-lysine) binds copper(II) ions with high affinity, and most of its reported activity is attributed to this copper complex. No classical membrane receptor has been identified; the peptide appears to act through copper delivery into cells and broad modulation of gene transcription. Gene-expression analyses associate GHK with altered expression of a large number of human genes, including many involved in tissue remodeling and repair (Pickart & Margolina 2018). In vitro, GHK-Cu stimulates collagen synthesis in dermal fibroblast cultures (Maquart et al. 1988) and promotes production of glycosaminoglycans and other extracellular matrix components. In fibroblast cultures, GHK-Cu also increased MMP-2 expression and the secretion of the tissue inhibitors TIMP-1 and TIMP-2 (Siméon et al. 2000), which is discussed as a mechanism of wound remodeling in preclinical models. Antioxidant and anti-inflammatory effects have additionally been described in cell and animal studies.
State of evidence
The evidence base for GHK-Cu is predominantly preclinical. Most published data come from in vitro systems, such as fibroblast cultures and gene-expression profiling, and from animal wound-healing models. Human data are limited to small topical studies in the cosmetic context, typically on facial skin, which were often industry-affiliated, short, and not designed as registered controlled drug trials. There is no systematic clinical development programme: no phase 1, 2 or 3 trials of systemic GHK-Cu administration have been published, and the substance holds no regulatory approval as a medicinal product. Systemic pharmacokinetics in humans are not reliably characterized: no published human study of the plasma half-life of GHK-Cu is available, and the figures circulating in secondary literature contradict one another. Consequently, neither efficacy nor safety in humans has been established, and findings from cell and animal models cannot be extrapolated to humans. Note also that a substantial share of the review literature on GHK-Cu originates from the substance's discoverer, who also markets it commercially; independent confirmation is correspondingly scarce. GHK-Cu therefore remains a research compound.
Storage and handling
Lyophilized peptides are generally handled according to well-documented principles: store cool, dry and protected from light. After reconstitution, peptide solutions are typically kept refrigerated at 2-8 °C in laboratory practice and used within a few days. These are generic peptide-handling notes, not product-specific stability data for GHK-Cu.
Questions about the research
- What is GHK-Cu studied for in research?
- GHK-Cu is studied mainly in skin and wound research, for example with regard to collagen synthesis, extracellular matrix remodeling and gene expression in repair processes. The data base consists largely of cell culture and animal models, supplemented by small topical studies in the cosmetic context. No conclusions about effects in humans can be drawn from this.
- What is the state of the evidence on GHK-Cu?
- The evidence is predominantly preclinical: in vitro data and animal models dominate, while controlled clinical trials of systemic administration are lacking. There is neither a systematic clinical development programme nor approval as a medicinal product. Efficacy and safety in humans have not been established.
Sources
- Pickart & Margolina, Int J Mol Sci 2018DOI: 10.3390/ijms19071987PMID: 29986520
- Pickart et al., Oxid Med Cell Longev 2012DOI: 10.1155/2012/324832PMID: 22666519
- Pickart et al., BioMed Res Int 2015DOI: 10.1155/2015/648108PMID: 26236730
- Siméon et al., Life Sci 2000DOI: 10.1016/s0024-3205(00)00803-1PMID: 11045606
- Maquart et al., FEBS Lett 1988DOI: 10.1016/0014-5793(88)80509-xPMID: 3169264
- Pickart & Thaler, Nat New Biol 1973PMID: 4349963