It may not have an aesthetic-sounding appeal to most people, but salmon sperm is indeed one of the novel ingredients featured in products for human skin. These products also reportedly enhance and promote skin regeneration.1 This column will focus on the innovative approach to skin care involving purified polynucleotides derived from salmon sperm.
The Properties and Activities of PDRNs, PNs
PDRNs contain DNA fragments primarily derived from Pacific or chum salmon (Oncorhynchus keta), and salmon trout (Oncorhynchus mykiss) sperm cells.2 Through preclinical and clinical trials, PDRN has demonstrated a wide range of salutary functions, including antiallodynic, antiapoptotic, anti-inflammatory, antimelanogenetic, antiosteonecrotic, antiosteoporotic, antiulcerative, bone-regenerative, tissue damage–preventive, and wound-healing activities through adenosine A2A receptor and salvage pathways activation. Indeed, PDRNs have been shown in vitro to spur the proliferation of preadipocytes and, in vivo, to be effective in treating wounds and ulcers.3,4 In particular, atrophic, hypertrophic, surgical, and various acne scars have been treated with such injections.2,5,6 PDRN is thought to affect cutaneous health more directly by facilitating angiogenesis, cellular functions, especially fibroblast stimulation, collagen production, soft-tissue regeneration, and skin revitalization. Further, it has been used successfully to treat hyperpigmentation.7
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PNs, derived from the same fish species as PDRNs, have been used effectively to ameliorate skin elasticity, hydration, pore size, thickness, wrinkles, as well as pigmentation and, specifically, in treating periorbital rhytides and postsurgical scars.5,6,8 Beyond skin rejuvenation, PNs have been recognized for effectiveness in treating stretch marks and achieving vulvovaginal revitalization; guidelines for its use have been established and implemented in recent years.6,9,10 In South Korea, PNs have become a popular treatment for facial erythema even though preclinical and clinical data are sparse.11 Nevertheless, the use of these novel substances is thought to foster tissue regeneration and a more natural rejuvenation than achieved through more traditional fillers.6
Skin Rejuvenation
Park and colleagues conducted a small study with five patients in 2016 in which long-chain polynucleotide filler was used for skin rejuvenation. Over a 2-week period, five Korean women received four injections of the filler (0.05 mL) on one side of the face. No adverse side effects were reported. In the patients in their 30s, pore and skin thickness significantly improved with treatment. For patients in their 40s, observable improvements were noted in melanin, sagging, skin tone, and wrinkles. Despite the small study size, the investigators concluded that this intradermal injection material is a safe and effective product for skin rejuvenation therapy.1 The product is also available in Europe and reportedly spurs the regeneration of damaged tissues and yields a more natural appearance.1
A Hybrid HA-PN Filler
Given that the most common filling agent, hyaluronic acid (HA), is associated with multiple side effects, JH Kim and colleagues set out in 2020 to compare HA with a new HA-PN dermal filler that has displayed notable biocompatibility and promoted tissue regeneration. The investigators observed that the combination filler provoked greater cell migration in a wound healing assay and was more effective in promoting collagen production in human and mouse fibroblasts. To their knowledge, this was the first study showing the efficacy, safety, and durability of a hybrid HA-PN filler. They concluded that fillers containing both HA and PN were more effective than HA alone in suppressing cutaneous aging and may represent the next step in the evolution of dermal filling agents.12