reviewed april 2026|next review october 2026|88 physicians psi has verified|537589 published studies
GHK
GHK (glycyl-histidyl-lysine) is the base tripeptide from which GHK-Cu derives its biological activity, naturally released during collagen degradation and first identified by Pickart (1973) as a factor in human plasma that stimulated liver cell growth.
Evidence landscape: 537589 published studies
537,589 published items (very broad query). 16 human studies and 145 animal studies.
- 16 Human
- 145 Animal
- 39 Reviews
- 537389 Other research
GHK was first identified by Loren Pickart in 1973 as a factor in human plasma that stimulated liver cell growth in aging tissue. This discovery launched the entire copper peptide research field.
GHK is naturally (the body's own) released during collagen degradation. It functions as a matrikine signal peptide, signaling fibroblasts that tissue repair is needed.
GHK retains some biological activity independent of copper in cell culture. Whether these copper-independent effects are meaningful in vivo is the central open question. The published literature overwhelmingly studies the copper-bound form.
PSI Assessment
GHK is the three-amino-acid sequence at the foundation of the entire copper peptide family. First identified by Pickart in 1973 in human plasma, it is naturally (the body's own) released during collagen degradation and functions as a matrikine signal. With copper, it becomes GHK-Cu, the most extensively studied copper peptide (186 studies, 4,000+ gene modulation). Without copper, GHK retains some biological activity in cell culture models, but the published research overwhelmingly involves the copper-bound form. Whether the unmodified peptide has therapeutic or cosmetic utility independent of copper is the central open question.
Same three amino acids as GHK-Cu. Without copper: retains matrikine signaling, loses copper delivery. First identified in 1973 in human plasma.
GHK (Gly-His-Lys) is the base tripeptide that complexes with copper to form GHK-Cu. It was first identified by Pickart in 1973 as a factor in human plasma that stimulated hepatocyte growth. The tripeptide is naturally (the body's own) released during collagen degradation and functions as a matrikine, signaling fibroblasts and other cells that tissue repair is needed. GHK has high affinity for copper(II) (logK = 16.44), and in blood it rapidly complexes with available copper. The question of whether GHK has meaningful copper-independent effects is active. Cell culture data shows matrikine signaling activity without copper, but the published research overwhelmingly involves the copper-bound form. The relative contribution of peptide sequence signaling versus copper delivery to GHK-Cu's effects is not quantified.
What the evidence supports
GHK was first identified by Pickart in 1973 as a growth factor in human plasma. The tripeptide is naturally released during collagen degradation and functions as a matrikine signal. GHK retains some biological activity independent of copper binding in cell culture models. The sequence is the foundation for the entire copper peptide family.
What is not yet established
Whether GHK without copper delivers meaningful biological effects in vivo. The published research overwhelmingly involves the copper-bound form. The relative contribution of matrikine signaling versus copper delivery to GHK-Cu's documented effects. Whether GHK alone has therapeutic or cosmetic utility independent of copper.
Research Evidence
The findings below cover the Pickart discovery, the copper-independent activity question, and the relationship to GHK-Cu.
Evidence by condition
Evidence dimensions for GHK. The matrikine signaling mechanism is established. Copper-independent in vivo effects are not demonstrated.
| Condition | Mechanism | Animal evidence | Human evidence | Replication |
|---|---|---|---|---|
| Signal Peptide Biology | ||||
| Collagen Signaling | ||||
| Copper-Independent Effects |
GHK was first identified by Pickart in 1973 as a growth factor in human plasma. The discovery that this tripeptide stimulated liver cell growth in aging tissue launched the copper peptide research field.
The original discovery focused on the GHK-Cu complex. Whether Pickart's growth-stimulatory effect required copper or was peptide-intrinsic was not separated in the initial work.
Cell culture studies show GHK retains matrikine signaling activity independent of copper binding. The peptide stimulates fibroblast migration and collagen synthesis signaling without copper in some experimental conditions.
Cell culture results do not confirm in vivo utility. The relative contribution of matrikine signaling versus copper delivery to GHK-Cu's documented effects across 4,000+ genes is not quantified.
The published GHK literature is dominated by the copper-bound form (GHK-Cu, 186 studies). Dedicated studies of the copper-free peptide are a small fraction of the total evidence base.
Tripeptide-1 (the INCI cosmetic name for GHK) and palmitoyl tripeptide-1 (the palmitoylated form) inherit their scientific reputation from GHK-Cu research. Whether the copper-free forms deliver equivalent effects is not established.
16 Human|145 Animal|39 Reviews
View all 537589 indexed studiesHow GHK Works
GHK (glycyl-histidyl-lysine) is a naturally occurring (the body's own) tripeptide released during collagen degradation that functions as a matrikine signal and has high affinity for copper(II) (logK = 16.44), forming the GHK-Cu complex.
Naturally binds copper in blood. Together as GHK-Cu they activate tissue repair.
For a more detailed view of the biology, here is what researchers have observed at the molecular level.
High affinity for Cu(II) ions. Apo-peptide can modulate TGF-beta signaling independently.
What is GHK being studied for?
Researchers are studying GHK across several health conditions. Each condition below is labeled with the strength of evidence that exists for that specific use, not for GHK overall. This means a compound can have human studies for one condition but only animal data for another.
Signal Peptide Biology
·Animal StudiesGHK is a matrikine naturally (the body's own) released during collagen degradation. The signaling mechanism is well-characterized. First identified in human plasma in 1973.
Limitations: The matrikine biology is established for the GHK sequence. Whether this translates to therapeutic or cosmetic utility without copper is the open question.
Collagen Signaling
·Animal StudiesGHK stimulates collagen production in fibroblast cultures. The matrikine mechanism signals fibroblasts that tissue repair is needed.
Limitations: Whether collagen signaling from the copper-free peptide produces clinically meaningful effects in vivo is not established. The copper-bound form is the clinically relevant compound.
Copper-Independent Effects
·PreclinicalCell culture data shows some GHK biological activity without copper binding. The matrikine signaling pathway is copper-independent at the receptor level.
Limitations: In vivo copper-independent effects are not demonstrated. The published research overwhelmingly involves GHK-Cu. The relative contribution of matrikine signaling versus copper delivery is not quantified.
Safety and Regulatory Status
FDA Status: Not regulated as a drug. Used as a cosmetic ingredient. The copper-bound form (GHK-Cu) is the compound with regulatory significance.
Availability: Available in cosmetic products. More commonly used in copper-bound (GHK-Cu) or palmitoylated (palmitoyl tripeptide-1) forms.
Class context: Naturally occurring (the body's own) tripeptide. The foundation of the copper peptide family. Present in human plasma with levels declining approximately 60% between the 20s and 60s.
Naturally occurring (the body's own) peptide present in human plasma. Excellent safety profile consistent with its natural origin. No safety concerns from topical application.
Peptide Structure
Technical molecular data for researchers and clinicians.
Questions and Comparisons
Questions the evidence raises for a GHK discussion.
Comparison and Related Research
GHK is most often compared with GHK-Cu (copper-bound, full mechanism), palmitoyl tripeptide-1 (palmitoylated GHK), and tripeptide-1 (same molecule under INCI naming).
Related compounds
Frequently Asked Questions
References
Each citation links to the original study on PubMed, the U.S. National Library of Medicine database.
- 1.Review of GHK biological activities covering the original 1973 discovery in human plasma, copper-binding properties (logK = 16.44), matrikine signaling function, and the question of copper-independent biological activity of the base tripeptide sequence.Pickart L, 2008 in J Biomater Sci Polym Ed. View on PubMed
- 2.Review examining GHK-Cu and the GHK sequence in the context of aging, oxidative stress, and tissue protection. The paper discussed both copper-dependent and copper-independent activities of the tripeptide.Pickart L et al., 2012 in Oxid Med Cell Longev. View on PubMed
Medical Disclaimer
This content is for educational and informational purposes only and does not constitute medical advice. The information presented reflects published research as indexed by PSI and should not be used to make treatment decisions. Always consult a qualified healthcare provider before starting, stopping, or modifying any treatment.