Polynucleotides are DNA fragments, usually from salmon or trout. Exosomes are tiny vesicles that cells release to carry messages. They are often mentioned in the same breath, but they are different ingredients with different origins.
What are polynucleotides?
Polynucleotides are chains of nucleotides, the building blocks of DNA. In aesthetics they are usually purified from fish DNA, most often salmon or trout. They are used in injectable treatments and in some topical products.
A 2025 systematic review in the Journal of Cosmetic Dermatology looked at published evidence on polynucleotides in aesthetic medicine. As with many newer treatments, the authors highlight the need for more high-quality research.
What are exosomes?
Exosomes are extracellular vesicles, tiny packages that cells use to carry proteins and other molecules to neighbouring cells. They are part of a larger group of substances that cells release, known as the secretome.
Side-by-side comparison
| Polynucleotides | Exosomes | |
|---|---|---|
| What they are | DNA fragments | Extracellular vesicles released by cells |
| Usual source | Salmon or trout DNA | Cultured cells |
| How they are used | Injectable and topical | Mostly topical and in-clinic |
| Part of the secretome? | No | Yes |
Where does secretome fit?
Secretome is the complete set of substances cells release: growth factors, peptides, cytokines and extracellular vesicles, including exosomes. If exosomes are one voice in a conversation between cells, secretome is the whole conversation. Read our full guide to secretome vs exosomes.
Which is right for you?
These ingredients are used in different ways and for different reasons, and many clinics offer more than one. The best person to advise you is a qualified practitioner who has assessed your skin and knows your treatment plan.
If you are having treatments such as microneedling, laser or peels, ask your clinic what aftercare they recommend and why. Always follow the aftercare advice your practitioner gives you.
Frequently asked questions
Are polynucleotides the same as exosomes?
No. Polynucleotides are DNA fragments, usually from fish. Exosomes are vesicles released by cells.
Where do polynucleotides come from?
In aesthetics they are usually purified from salmon or trout DNA.
Are polynucleotides part of the secretome?
No. The secretome is made up of substances cells release, such as growth factors, peptides, cytokines and extracellular vesicles.
Are polynucleotides injected?
They are used in both injectable treatments and some topical products.
How are exosome products used?
Exosomes are found in topical skincare and in some in-clinic treatments. Ask your practitioner exactly how any product will be used and what it contains.
Which is better, polynucleotides or exosomes?
They are different ingredients used in different ways. A qualified practitioner who has assessed your skin is best placed to advise.
Can you have both?
Some clinics use more than one approach. Your practitioner can advise what suits your skin and treatment plan.
What is the difference between exosomes and secretome?
Exosomes are one part of the secretome. Secretome is the full mix of signals a cell releases.
Sources
Having a treatment? Ask your clinic about Sekretome aftercare.
