Comparing the regenerative injectables

6.4.1The category is a marketing artefact

Regenerative is a word that has been applied to a set of treatments that arrived at roughly the same time and appeal to the same impulse: the wish for a treatment that improves tissue rather than filling it. That impulse is entirely reasonable. The category built on it groups materials that a biochemist would not put in the same room.

The practical consequence is that a patient comparing options within the category is comparing things on a dimension that does not exist. What follows sets out what each one actually is.

6.4.2Polynucleotides

Covered throughout this document. Fragmented purified fish DNA in buffer, degraded within weeks, no reversal agent, plausible mechanism, thin evidence for the central claim about lasting effect.

6.4.3Platelet rich plasma

Your own blood is drawn, centrifuged to concentrate the platelet fraction, and the resulting plasma is reinjected. Because it is autologous, the material is by definition compatible with you, which removes an entire class of concerns and introduces others.

Preparation varies enormously between systems and between operators, which is the central difficulty with the evidence: two studies of platelet rich plasma may be studying materially different preparations. The category has been studied in several fields including orthopaedics and hair loss, with mixed results and considerable heterogeneity. It also involves handling blood, which brings its own procedural requirements.

6.4.4Exosome products

Preparations of extracellular vesicles, marketed for injection or for application after procedures that breach the skin. The regulatory position is the important issue here rather than the biology. In several jurisdictions regulators have taken the view that products of this kind fall within medicines or biological product frameworks and have raised concerns about products marketed outside them.

A patient considering an exosome product should establish, first, what the product actually is, who makes it and what its regulatory status is in the United Kingdom. That question comes before any question about effect, and the answer is frequently less clear than the marketing.

6.4.5Hyaluronic acid skin boosters

Thin, minimally cross linked or uncross linked hyaluronic acid injected in multiple small deposits to hydrate rather than to shape. Bacterially fermented, so not animal derived. Reversible with hyaluronidase. The water binding effect is undisputed physical chemistry, and claims of biostimulation beyond that vary by product and sit on the same kind of ground as the polynucleotide claim.

6.4.6Collagen stimulators

Poly L lactic acid and calcium hydroxylapatite are synthetic materials injected to provoke a tissue response over months. They are a genuinely different proposition: they persist for a substantial period, they are not reversible with hyaluronidase, they are used at deeper planes, and they can produce nodules. They are not skin quality treatments in the same sense and are generally used for volume and structure.

6.4.7What can and cannot be compared

You can compare origin, persistence, reversibility, regulatory route, and the general shape of each evidence base. Those are real, checkable differences.

What cannot be compared, on current evidence, is effectiveness. Head to head trials between these categories, adequately powered, blinded and with long enough follow up, are what would allow it, and they are not what the field has produced. Any table you are shown that ranks these treatments against each other on results is a table someone constructed rather than measured.

6.4.8A framework rather than a ranking

• If reversibility matters most to you, hyaluronic acid is the only one of these with a specific corrective agent.
• If avoiding animal derived material matters, hyaluronic acid and the synthetic stimulators are not animal derived; polynucleotides are.
• If you want the most established evidence base, the water binding effect of hyaluronic acid is the least disputed thing in this list, which is a modest claim rather than a grand one.
• If regulatory clarity matters, ask about status product by product. This is where exosome products most often produce an unsatisfying answer.
• If you want volume or structural change, none of the skin quality treatments in this list is the relevant category.
• If the appeal is the regenerative idea itself, that is the part with the least secure evidence across the whole category, not only for polynucleotides.

6.4.9The uncomfortable summary

The regenerative injectable category as a whole is characterised by plausible mechanisms, enthusiastic marketing, small and heterogeneous evidence bases, and a shortage of head to head comparison. Polynucleotides are neither the best nor the worst evidenced member of it.

A person choosing between them on the basis of the published record is choosing between options none of which has been established to the standard the claims imply. That is a legitimate thing to do with your own money, provided you know it is what you are doing.