# What makes a good peptide for repair?

> Good Peptide — An interest in repair — Good Peptide follows GHK-Cu through collagen, skin delivery, hair and gene research, looking for the particular work behind the praise.

**The repair question**

The untidiness of repair appeals to me. GHK-Cu gives that curiosity somewhere to go: collagen, copper, a stubborn skin barrier and a few results worth arguing over.

## Collagen at the workbench

A good peptide sounds like a settled judgment. Give it a job, though, and the interesting questions begin. Making collagen? Getting through skin? Helping a follicle grow? I’m willing to admire a small, well-described success. A general certificate of goodness feels much harder to earn.

GHK-Cu starts here with a beautifully particular experiment. In [human fibroblast cultures, it increased collagen synthesis without changing cell number](https://pubmed.ncbi.nlm.nih.gov/3169264/). Fibroblasts are cells that make connective-tissue material. The cells were doing more of the measured work; the culture had not simply acquired more workers. That distinction is enough to make me interested.

The [collagen essay](/collagen) begins at that bench and follows the broader remodeling argument. It is the best place to start if the attraction of GHK-Cu is the possibility of repair.

## Skin puts up a barrier

Then comes the awkward physical question: how does the material reach its destination? A [skin-layer experiment measured copper passing through human skin outside the body and copper retained within it](https://pmc.ncbi.nlm.nih.gov/articles/PMC3016279/). A [later review identifies poor permeability as a central problem for GHK](https://pmc.ncbi.nlm.nih.gov/articles/PMC11830136/).

That combination draws me into the practical details. There is an actual barrier in this story, with actual material on either side of it. The [delivery essay](/skin-barrier) spends time there, where an elegant cellular result meets the less accommodating business of getting through skin.

## A follicle and a long list of genes

The hair literature has a detail that changes the entire conversation: the [controlled human trial used GHK together with 5-aminolevulinic acid](https://pmc.ncbi.nlm.nih.gov/articles/PMC4969472/). I can appreciate its result while leaving the credit shared. The [hair essay](/hair-trial) also meets a copper-peptide cousin whose initials deserve close attention.

At a different scale, a [gene-expression analysis reports broad changes in cellular activity](https://pmc.ncbi.nlm.nih.gov/articles/PMC6073405/). I’d put the changes relevant to repair ahead of the list’s sheer size. The [gene-data essay](/gene-data) gets into the threshold behind the headline figure.

Good is a useful word when it invites this sort of curiosity. My enthusiasm for GHK-Cu grows around particular tasks and remains provisional about the larger promises.

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At Good Peptide I follow published repair research with curiosity and a willingness to revise a verdict, without offering medical advice or a treatment service.