| Mazurowska 2007 Talanta Laboratory analytical methods · Skin research · Copper binding | ChemistryNo organism Flynn diffusion cell with a liposome model membrane GHK-Cu (copper complex) | The study identified the copper complexes present at different pH by ESI-MS and measured permeability coefficients through a model stratum corneum membrane that increased with pH. | Artificial membrane, not skin. | Evidence grade D |
| Wang 2017 Wound Repair Regen Collagen and extracellular matrix · Skin research | Animaltopical HUVEC cultures; mouse scald model GHK-Cu (copper complex) | The study measured a 33.1% higher endothelial-cell proliferation rate with GHK-Cu liposomes and compared CD31 and Ki67 staining and healing time in mice treated with liposomal versus free GHK-Cu. | Mice; liposomal formulation; abstract truncated in PubMed. | Evidence grade C |
| Parker 2013 Otolaryngol Head Neck Surg Collagen and extracellular matrix · Skin research | Animaltopical Irradiated rat dorsal skin flaps GHK-Cu (copper complex) · n = 23 (13 test, 10 control) | The study measured ischaemic flap area, caveolin-1 and VEGF staining; mean ischaemic area was 5.0 cm² with GHK-Cu gel and 3.8 cm² with the control ointment. | Rats; the measured ischaemic area was larger in the GHK-Cu group. | Evidence grade C |
| Cangul 2006 Vet Dermatol Collagen and extracellular matrix · Skin research | Animaltopical New Zealand rabbits, full-thickness dorsal wounds GHK-Cu (copper complex) · n = 18 | The study measured unhealed wound area and contraction on days 7, 14 and 21; the copper-complex group had smaller unhealed areas than the untreated group at each time point. | Rabbits; small groups. | Evidence grade C |
| Canapp 2003 Vet Surg Collagen and extracellular matrix · Skin research | Animaltopical Rat full-thickness wounds in an ischaemic skin flap GHK-Cu (copper complex) · n = 24 | The study measured wound area daily for 13 days and TNF-α, MMP-2 and MMP-9 in biopsies; wound area decreased in the gel group but not the vehicle group compared with no treatment. | Rats; abstract truncated in PubMed. | Evidence grade C |
| Buffoni 1995 Arch Int Pharmacodyn Ther Collagen and extracellular matrix · Skin research | Animaltopical Guinea-pig dorsal skin wounds; cultured fibroblasts GHK-Cu (copper complex) | The study measured hydroxyproline, protein, DNA and amine-oxidase activity and observed slower skin reorganisation and delayed fibroblast activation with the copper-peptide complexes. | Guinea pigs; findings run opposite to several other animal reports. | Evidence grade C |
| Jiang 2023 J Cosmet Dermatol Collagen and extracellular matrix · Skin research | Ex vivoCell culture Human dermal fibroblasts; ex vivo skin Multi-ingredient product | The study measured collagen I, IV and VII expression across GHK-Cu and hyaluronic acid ratios and reported collagen IV increases of 25.4-fold in cells and 2.03-fold in ex vivo skin at a 1:9 ratio. | Combination with hyaluronic acid; mRNA in cells and staining in excised skin. | Evidence grade D |
| Lee 2022 Pharmaceutics Skin research | Ex vivotopical Pig and mouse skin in Franz diffusion cells GHK-Cu (copper complex) | The study found that all tested laser modalities increased skin permeation of the peptides in vitro, with non-ablative lasers disrupting the stratum corneum ultrastructure. | Animal skin; delivery outcome only. | Evidence grade D |
| Li 2015 Pharm Res Skin research · Safety and tolerability data | Ex vivotopical Two in vitro skin models; cell and pig models for safety GHK-Cu (copper complex) | The study found that microneedle depth depended on application force and measured 134 ± 12 nmol of peptide and 705 ± 84 nmol of copper permeating through microneedle-treated skin in 9 hours. | Delivery study; does not measure any skin outcome in people. | Evidence grade D |
| Hostynek 2011 Inflamm Res Skin research · Laboratory analytical methods | Ex vivotopical Human skin layers in flow-through diffusion cells GHK-Cu (copper complex) | The study reported the same permeability coefficient (2.43 ± 0.51 × 10⁻⁴ cm/h) and 136.2 µg/cm² copper permeated, with 97 µg/cm² retained in dermatomed skin. | Near-duplicate of the 2010 report by the same group with a different retained-copper figure; measures copper, not intact peptide. | Evidence grade D |
| Hostynek 2010 Inflamm Res Skin research · Laboratory analytical methods | Ex vivotopical Human skin layers in flow-through diffusion cells GHK-Cu (copper complex) | The study measured a permeability coefficient through dermatomed skin of 2.43 ± 0.51 × 10⁻⁴ cm/h, with 136.2 µg/cm² copper permeated over 48 h and 82 µg/cm² retained. | Measures copper, not intact peptide; infinite-dose conditions; excised skin. | Evidence grade D |
| Mazurowska 2008 J Cosmet Sci Skin research | Ex vivotopical Skin barrier models GHK-Cu (copper complex) | The study measured penetration of copper complexes of GHK and of glutathione through the stratum corneum in vitro. | Abstract truncated in PubMed; in vitro barrier model. | Evidence grade D |
| Patel 2025 Cureus Skin research | Humantopical Women with acne scars Multi-ingredient product · n = Not reported in the abstract | The study assessed visible scar change on the Manchester Scar Scale by a dermatologist with a multi-ingredient gel. | No control group; four actives in one gel, so no attribution to the copper peptide. | Evidence grade B |
| Patel 2024 Cureus Hair research · Skin research | Humantopical Adults with mild-to-moderate scalp flaking Multi-ingredient product · n = Not reported in the abstract | The study measured adherent scalp flaking, scalp hydration, hair density and hair thickness over 15 days of a two-product regimen. | No control group; 15 days; two products and several actives, so no attribution to the copper peptide. | Evidence grade B |
| Byun 2016 J Cosmet Laser Ther Skin research · Collagen and extracellular matrix | Humantopical One adult, periocular skin Multi-ingredient product · n = 1 | The case report described photographs and biopsy staining (collagen, fibrillin-1, procollagen type 1) from treated and untreated areas in one person. | One person; five active ingredients plus a device; cannot attribute any finding to GHK-Cu. | Evidence grade B |
| Trookman 2009 J Clin Aesthet Dermatol Skin research | Humantopical Women 22–40 with mild-to-moderate lip dryness Multi-ingredient product · n = 32 | The study measured visual grading, corneometry, lip caliper dimensions and self-assessment over four weeks of a multi-ingredient lip product. | No control group; palmitoyl-GHK is one of many ingredients and not GHK-Cu, so no effect can be attributed to it. | Evidence grade B |
| Miller 2006 Arch Facial Plast Surg Skin research | Humantopical Adults after circumoral CO₂ laser resurfacing GHK-Cu (copper complex) · n = 13 completed | The trial found no significant difference in resolution of post-laser redness, wrinkles or overall skin quality on objective and blinded assessment; only patient-reported satisfaction differed (P = .04). | 13 completers; primary objective measures were null. | Evidence grade A |
| Mulder 1994 Wound Repair Regen Skin research · Collagen and extracellular matrix | Humantopical Adults with neuropathic plantar ulcers GHK-Cu (copper complex) · n = Not reported in the abstract | The trial reported median plantar-ulcer area closure of 98.5% with the gel vs 60.8% with vehicle (p < 0.05), a larger difference in ulcers over 100 mm², and fewer ulcer infections (7% vs 34%). | Sample size not given in the abstract; one 1994 topical gel; the authors note the effect depended on starting immediately after debridement. No independent replication is indexed. | Evidence grade A |
| Bishop 1992 J Vasc Surg Skin research · Collagen and extracellular matrix | Humantopical Adults with venous leg ulcers GHK-Cu (copper complex) · n = 86 evaluable | The trial measured ulcer size: silver sulfadiazine reduced it more than the copper tripeptide cream or placebo, and there was no difference between the copper tripeptide cream and placebo. | Single trial of one 1992 topical formulation; the comparison with placebo was null. | Evidence grade A |
| Ye 2026 Curr Issues Mol Biol Collagen and extracellular matrix · Skin research | In vitroCell culture Dermal fibroblasts Multi-ingredient product | The study measured elastin expression and secretion by dermal fibroblasts exposed to copper tripeptide-1, alongside two other ingredients tested for elastase and scaffold-gene effects. | Cell culture; combination study. | Evidence grade D |
| Hur 2020 J Pept Sci Skin research · Collagen and extracellular matrix | In vitroCell culture Cell cultures and skin delivery models Derivative or conjugate | The study compared GHK with a tetra-arginine conjugate and found faster cellular penetration and higher in vitro collagen biosynthesis with the conjugate. | Conjugate differs from GHK-Cu; the authors attribute part of the effect to the arginine tail itself. | Evidence grade D |
| Li 2016 Sci Rep Skin research · Safety and tolerability data | In vitroCell culture Human keratinocyte model GHK-Cu (copper complex) | The study compared irritation potential at the same concentrations and found GHK-Cu not cytotoxic and without significant change in the irritation markers measured, while the copper salts differed. | Keratinocyte culture model; not a human patch test; tested concentrations are those of the paper. | Evidence grade D |
| Gruchlik 2014 Acta Pol Pharm Skin research | In vitroCell culture Normal human dermal fibroblasts GHK-Cu (copper complex) | The study measured IGF-2-dependent TGF-β1 secretion by dermal fibroblasts exposed to 1 nM GHK, GHK-Cu or copper chloride. | Abstract truncated in PubMed; single cell type. | Evidence grade D |
| Choi 2012 J Pept Sci Skin research | In vitroCell culture Normal human keratinocytes; skin-equivalent models GHK without copper | The study measured keratinocyte proliferation and staining for integrins α6 and β1, p63 and PCNA in skin equivalents cultured with copper-free GHK. | Cultured cells and engineered tissue. | Evidence grade D |
| Gruchlik 2012 Acta Pol Pharm Skin research | In vitroCell culture Normal human dermal fibroblasts (NHDF) GHK-Cu (copper complex) | The study measured TNF-α-dependent IL-6 secretion and reported decreases with GHK, GGH, copper chloride and their copper complexes. | Single cell type; copper chloride alone also changed the readout. | Evidence grade D |
| Pollard 2005 Arch Facial Plast Surg Skin research | In vitroCell culture Primary human dermal fibroblasts, normal and previously irradiated, serum-free GHK-Cu (copper complex) | The study measured faster population-doubling times in normal and irradiated fibroblasts exposed to GHK-Cu than in untreated controls, and their bFGF, TGF-β1 and VEGF output. | Cultured cells from surgical specimens. | Evidence grade D |
| McCormack 2001 Arch Facial Plast Surg Skin research | In vitroCell culture Primary human facial dermal fibroblasts (normal and keloid-derived), serum-free GHK-Cu (copper complex) | The study measured fibroblast viability and secretion of basic FGF and TGF-β1 after copper tripeptide or tretinoin exposure. | Primary cell lines from surgical samples; abstract truncated in PubMed. | Evidence grade D |