Exosomes

How it works

Exosomes are extracellular vesicles: membrane-wrapped packets, tens of nanometres across, that cells release carrying proteins, lipids and RNA. They are a genuine and important part of how cells communicate, and the underlying biology is real and actively researched.

The cosmetic proposition is that applying vesicles harvested from cultured cells delivers those signals into skin, prompting fibroblasts to behave as they would in younger or healing tissue. The immediate difficulty is physical. The stratum corneum is a formidable barrier to anything of that size, and how much intact vesicle reaches living tissue after being spread on unbroken skin is not established.

The evidence

This is where a reader deserves plain language. There is no agreed definition of what a topical exosome product must contain, no standard for characterising or quantifying it, and no requirement to disclose the source. Products described as exosome-based range from plant-derived vesicles to conditioned media from human or animal cell culture, and two products using the word may have almost nothing in common.

Published independent trials applying these preparations to intact human skin and measuring an outcome are scarce. Most of what circulates is laboratory work, manufacturer data or clinic reports alongside a procedure that would itself produce change. Separately, medicines regulators have warned about unapproved injected exosome products and have reported serious adverse events, which is a different route of administration but a fair signal about how unsettled the field is.

Suitability

• Hard to justify for anyone on current published evidence
• Not appropriate on broken skin or immediately after a procedure without a clinician's direction
• Not suitable for anyone avoiding animal- or human-derived material unless the source is documented
• Anyone drawn to it would be better served by retinoids, sun protection and vitamin C, which have the trial record this does not

Concentration

There is no meaningful figure, and a stated particle count is not one. Without a standard method for counting, characterising and verifying vesicle integrity in a finished cosmetic, a number on a box is unverifiable rather than informative. This entry leaves it blank because inventing a threshold for a category that has not agreed on a measurement would be worse than saying nothing.

Conflicts & combinations

Nothing documented, and given how little is standardised, an absence of documented interactions says little. The practical caution is procedural rather than chemical: applying an unstandardised biological preparation to skin that has been microneedled, lasered or otherwise breached bypasses the barrier that keeps most cosmetic risk theoretical. That is a decision for a clinician, and it is where the reported harms have clustered.