# The chemical afterlife — LumiDerm Skin Clinic

> LumiDerm Skin Clinic explores what ingredients become around skin cells: NAD breakdown, retained copper, collagen synthesis and visible outcomes.

**Skin chemistry after arrival**

Ingredients arrive with names. Skin experiments give them fates: breakdown products, retained copper and changes in what cells make. Following those fates is delightfully untidy.

## NAD at a fibroblast’s surface

Cells are unceremonious hosts. In [human skin fibroblast cultures, added NAD was broken down outside the cells](https://pubmed.ncbi.nlm.nih.gov/11135366/). Enzymes at the cell surface produced nicotinamide, nicotinamide mononucleotide and purine metabolites. Adenosine was the principal breakdown product taken up by the cells and further metabolized to intracellular ATP. I expected intact material to supply the plot. Dismantling supplies a better one.

An ingredient can have an afterlife in chemistry. Its products enter reactions under different names, making the original name a surprisingly incomplete account of what happened. This experiment concerns cultured human skin cells, with NAD added outside them. It gives the afterlife a specific setting.

LumiDerm suggests lighting up skin; I prefer the surprise of what happens after an arrival. The [NAD essay](/metabolic-fate) starts with those busy cell surfaces and follows the products of breakdown. The cells have complicated the guest list.

## A dermal depot

Copper supplies a different sort of trace. In a study of human skin outside the body, copper applied as a GHK-Cu tripeptide [passed through dermatomed skin and accumulated in a dermal depot](https://pmc.ncbi.nlm.nih.gov/articles/PMC3016279/). Over 48 hours, the investigators reported both permeation and retention. A depot is material retained in a tissue; here, the measured material was copper.

The word retained has a pleasing physical weight. Where the NAD experiment follows breakdown products into cells, the skin-layer experiment locates a metal in prepared tissue. I call the latter an afterimage: something remains, and its significance becomes the next subject of curiosity.

The [copper-depot page](/copper-depot) sets the reported amounts beside each other. Chemical form and tissue response would make fascinating companions to that measurement. A retained amount gives those questions somewhere to begin.

## Cellular production and visible skin

An ingredient can also leave a response to examine. GHK-Cu [increased collagen synthesis in human fibroblast cultures without changing cell number](https://pubmed.ncbi.nlm.nih.gov/3169264/). Fibroblasts make supporting material in tissue. This experiment catches them changing an activity, which is why the [collagen essay](/collagen) concentrates on production.

The [skin-regeneration review](https://pmc.ncbi.nlm.nih.gov/articles/PMC4508379/) describes improvements in laxity, clarity, fine lines, wrinkle depth and density in the clinical studies it discusses. Those findings bring the question back to visible skin. Persistence would be particularly interesting: the same feature assessed again after application ends.

My enthusiasm has acquired a taste for leftovers. A breakdown product, copper in a tissue and an altered cellular activity each make a better subject than an undifferentiated claim of renewal. The [visible-changes essay](/skin-claims) considers the cosmetic outcomes, while the [reading list](/references) gathers the experiments and reviews behind the collection.

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LumiDerm Skin Clinic is my notebook of published research on ingredients’ chemical afterlives; it is not a business and offers no medical advice.