GHK-Cu references, including the awkward result

The experiments I’d reopen first

Maquart’s collagen cultures and Simeon’s copper-dependent MMP-2 work anchor the mechanism argument. Their value lies in the particular responses they measured. The SPARC paper adds an endogenous source of angiogenic peptides and a qualification to the idea that every response requires prior copper binding.

For human outcomes, the combination hair trial and the post-laser trial pull the reputation in different directions. One reports hair-count gains with another ingredient in the formulation; the other reports higher satisfaction without a significant objective redness benefit. I consider the latter essential company for the favorable skin findings.

The skin-penetration experiment belongs between a claim about a molecule and a claim about a topical preparation. The 2025 anti-wrinkle review revisits that delivery difficulty. The bibliography below retains the full study record, including rat behavioral work, biomaterial experiments and reviews that should not be mistaken for human systemic trials.