GHK-Cu and cellular collagen output
The useful surprise is the unchanged cell count. It sharpens the question about what the cells were doing.
Production and cell number
In the human fibroblast-culture experiment, GHK-Cu stimulated collagen synthesis without a change in cell number. Fibroblasts are cells involved in making the material around them. The result concerns increased production by a culture whose cell count did not change.
That separation earns my respect. A larger population could complicate an apparent increase in total production; here the cell-count observation supports a specific metabolic effect. The paper gives the collagen result a second measurement to stand beside.
This is human cellular material studied in vitro. The defined effect earns my enthusiasm; the appearance of a person’s skin remains an open question. An assay of collagen synthesis and a visible skin outcome ask different questions.
The concentration response in the dish
The study reports stimulation beginning between 10^-12 and 10^-11 M, with a maximum at 10^-9 M. These are concentrations in cell-culture medium. They describe this experiment, with no human regimen implied.
I value a response curve more than an isolated favourable measurement. It offers another way to interrogate the effect: how the response changes across the conditions tested. At the same time, a culture concentration supplies no shortcut to knowing exposure in a person’s skin.
The gene-expression review makes a broad molecular claim about GHK. This collagen experiment tests the copper complex, GHK-Cu, and records a defined cellular outcome. I cannot assume that the broad pattern explains this particular result merely because the names are related. That connection is a further experimental question.
Interpreting the culture experiment
The combination earns my respect: a named substance, a concentration response, increased collagen synthesis and an unchanged cell count. Each part helps locate the finding. An equally precise account of exposure and response in intact skin would satisfy a further curiosity of mine.
The penetration experiment approaches the exposure question from another direction. Instead of adding the substance directly to culture medium, it puts a skin sample between application and detection.