From clinic to cabinet: how polynucleotide skincare is translating injectable results to topical formulas

The injectable polynucleotide origin story

Polynucleotides (PNs) and polydeoxyribonucleotides (PDRNs) entered aesthetic medicine as injectable wound-healing agents used post-procedure and for skin laxity — particularly prominent in South Korea under the name "rejuran healer" injections. Injectable polynucleotides work by providing a scaffold of DNA fragments (from salmon sperm, purified to remove immunogenic proteins) that stimulate fibroblast proliferation, increase collagen synthesis, and support angiogenesis (new blood vessel formation) in the dermis. The results in injectable form are documented and significant: measurable improvement in skin density, texture and hydration depth over a course of monthly treatments. This clinical origin is what drives the high expectations around topical polynucleotide products.

What topical polynucleotides can reasonably achieve without injection

The transition from injectable to topical delivery involves an inherent limitation: polynucleotide molecules are large (the DNA fragment polymers used in injections range from several hundred to several thousand base pairs in molecular weight) and do not penetrate the intact skin barrier efficiently in intact form. However, recent research has demonstrated three things that make topical PN products scientifically interesting rather than simply market-following. First, hydrolysed or low-molecular-weight PN fragments show evidence of partial skin penetration. Second, even surface-level PN application appears to signal fibroblasts through receptor-mediated pathways that may not require full dermal delivery. Third, PN on the skin surface contributes to barrier support and hydration depth through humectant and film-forming properties that improve skin quality independent of the fibroblast mechanism.

Salmon DNA extract versus synthetic polynucleotides in skincare

Most polynucleotide skincare uses salmon-derived DNA extract — highly purified polynucleotides from salmon testes — as the active, the same source used in injectable rejuran products. This marine origin requires manufacturing controls to ensure the removal of proteins that could trigger immune reactions (the purification challenge that limited early injectable PN development). Synthetic polynucleotide sequences, produced through controlled chemistry rather than extraction, are beginning to appear in some formulas — they offer more precise molecular weight control and eliminate the animal sourcing concern for vegan consumers, though the clinical evidence base is currently smaller than for salmon-derived PN.

Toner versus serum delivery format for polynucleotide actives

Polynucleotide actives are delivered in both toner and serum formats in the Korean skincare market, and the format choice involves real functional trade-offs. A PN toner applies the active at the first and most absorptive step of a routine — immediately after cleansing when skin permeability is temporarily increased from the surfactant and water contact. A PN serum typically carries higher concentration in a more complex formula that may include complementary actives (niacinamide, peptides, hyaluronic acid). The sequential approach — PN toner for first delivery, then PN serum for concentrated follow-up — duplicates the application format of the most intensive clinical PN protocols, where building the dermal concentration of PN over time through consistent layered delivery is the mechanism.

Building a Rejuran-centred protocol for skin density and repair

A Rejuran-based skincare protocol places the PN products at the treatment step of both morning and evening routines: after cleansing and any preparatory toning, before heavier moisturisers that would block the active's contact with the skin. Morning application supports the daytime maintenance of fibroblast activity and provides the humectant and surface-repair benefit alongside SPF. Evening application aligns with the skin's peak nocturnal repair window, when cellular division and protein synthesis are most active. The meaningful evaluation period for structural skin density improvement is three to four months of consistent twice-daily application — a timeline that reflects collagen synthesis cycles rather than surface hydration, which is visible within days.