In a guinea‑pig skin wound model, the copper‑bound tripeptide GHK‑Cu (and similar synthetic versions) slowed the early re‑organization of the wound and delayed fibroblast activation, but later boosted an enzyme linked to healing. In cultured fibroblasts, a very low concentration (10⁻⁷ M) reduced cell division while increasing collagen production.

The effects of Gly-His-Lys-Cu and of three synthetic analogues (I, II and III) on wound healing of the guinea-pig dorsal skin, as well as on cultured fibroblasts, were examined. Gly-His-Lys-Cu and peptide I-Cu were tested in vivo. Hydroxyproline, proteins, DNA and semicarbazide-sensitive amine oxidase, with a high affinity for benzylamine, were measured, and the histology of the wounds was observed after staining with hematoxylin/eosin. Another set of wounds was treated in parallel with equivalent amounts of copper acetate. Gly-His-Lys-Cu and the analogues caused a decrease of the activity of semicarbazide-sensitive amine oxidase, with a high affinity for benzylamine, 4-8 days after surgery, followed by an increase on day 11 that was higher than in the control group. No significant difference was found between the two peptides. A slower reorganization of the skin and a delayed activation of fibroblasts are the main effects observed with these peptides-Cu complexes. Preliminary studies on cultured fibroblasts were monitored to see whether these peptides had a direct effect on fibroblasts. The products studied at a concentration of 10(-7) M, decreased cell reproduction and increased collagen expression.