What do PDRN, polynucleotides and "salmon DNA" mean?
Polynucleotides, shortened to PN, are chains of DNA building blocks purified for use on skin. PDRN, polydeoxyribonucleotide, is the same idea with a narrower definition. A 2026 narrative review in the Journal of Cosmetic and Aesthetic Surgery describes PN as the broader category and PDRN as a subset of it, separated by the size of the fragments.
The "salmon" in the nickname is literal. Both are mainly extracted from salmon, PDRN from the sperm cells and PN from wider gonadal tissue, because salmon tissue is rich in DNA. Plant sources have been tried, but the same review says they lack robust evidence. So "salmon DNA", PDRN and PN are overlapping names for a family of products, and they are not one standard ingredient.
How are they thought to work?
Two mechanisms are proposed. The first is that the fragments bind a receptor on cells called the adenosine A2A receptor, which in laboratory and some human studies is linked to reduced inflammation, collagen production and new blood vessel growth. The second is a salvage pathway, in which the fragments supply nucleotide building blocks to cells under stress. Both are described in the review as mechanisms with in vitro and some in vivo support, which is a step short of a proven clinical effect.
What does the trial evidence show?
A 2026 systematic review in Cureus gathered the randomised trials. It found seven, with 183 participants in total: four on skin rejuvenation, one on scar prevention after thyroid surgery, and two on wound healing. Benefit was strongest in wound healing, with faster closure and shorter healing times. The rejuvenation trials reported improvement in wrinkles and patient satisfaction, with smaller effects.
The review rated three studies at low risk of bias, three with some concerns and one at high risk, and called the overall evidence exploratory. Its authors point to small samples, differing treatment protocols and varied ways of measuring outcomes, and note that the absence of standard formulations makes it harder to compare studies or settle on a protocol. Read fairly, that is a promising early literature, not a settled one.
What are the risks and the gaps?
The same systematic review reported no serious treatment-related adverse events. Reactions were mostly mild and short-lived, and at the injection site, which is what any injection can do. The narrative review is more cautious about what is still unknown: dosing is not standardised, batches can differ, long-term safety data are limited, and regulation differs between regions.
Two practical points follow. Anyone with a known fish allergy should say so at assessment. And because the reviews cover clinical products, they do not tell you anything about a cosmetic serum labelled PDRN. What is in it, at what dose, is a separate question, and it is fair to ask for the product's registration details before paying for either.
Where does the clinic stand?
The Retreat Clinic uses polynucleotides as one component of ProNuLook, alongside high-dose hyaluronic acid and biostimulators. That is all this article claims for them. Whether they belong in a particular plan is decided at consultation, after looking at the skin, and it is separate from a skinbooster, which is usually hyaluronic acid for hydration.
Polynucleotides are also a different category from exosomes, another emerging product that the clinic does not offer, and the reasons are set out in the evidence on exosomes. The consistent position across both is to report what is known, say what is not, and decide suitability one patient at a time.
