PRP and PRF: what actually differs
Platelet rich plasma and platelet rich fibrin, how preparation changes composition, and why heterogeneous protocols make the literature hard to pool.
Platelet rich plasma is a fraction of a patient's own blood, prepared by centrifugation to concentrate platelets in plasma. Platelet rich fibrin is prepared without anticoagulant so that a fibrin clot forms, producing a solid or semi-solid material rather than a liquid.
The important point is that neither name specifies a composition. Spin speed, spin time, tube chemistry, whether the buffy coat is included and whether platelets are activated all change what is delivered. Two clinics can both offer PRP and deliver preparations that differ substantially, which is the main reason the published literature is so difficult to pool.
The one genuine advantage
Platelet preparations start from the patient's own blood. That removes an entire class of concern: there is no question of animal or foreign human material, no cell bank provenance question, no manufacturing supply chain, and the immunological questions are minimal. Compared with the sourcing problems that dominate our sourcing section, this is a substantial structural advantage and it deserves stating first.
It also creates the field's characteristic weakness. Because the starting material is the patient, it varies with the patient, and because the preparation is done on site, it varies with the protocol. The product is the protocol.
What actually varies
- Centrifugation parameters. Speed, duration and number of spins determine which components sediment and which remain. A single soft spin and a double spin protocol produce different preparations from the same blood.
- Leucocyte content. Whether the white cell layer is included is a major distinction, sometimes designated in the literature as leucocyte-rich or leucocyte-poor. White cells bring their own signalling profile, and opinion differs on whether their presence is desirable, which varies by indication.
- Anticoagulant and tube chemistry. Determines whether clotting is prevented, and some tube additives influence the separation.
- Activation. Platelets may be activated before delivery, causing release of their granule contents, or left to activate in tissue. This changes the timing of factor release.
- Final volume and concentration factor. How much plasma the platelets end up in determines the concentration delivered.
None of these is hidden or controversial. The problem is that studies frequently report the commercial system used rather than the resulting composition, and often do not report platelet concentration in the final preparation at all. Two trials of PRP may therefore be trials of materially different substances sharing a name.
PRF, and what removing the anticoagulant does
Platelet rich fibrin is prepared without anticoagulant, so clotting proceeds and fibrin forms. The result is a matrix rather than a liquid, containing platelets and often leucocytes within it. The argument made for it is that the fibrin scaffold holds the cells in place and releases factors over a longer period than an injected liquid, which is a coherent argument given the pulse problem discussed in paracrine signalling explained.
Whether the slower release translates into a better clinical outcome in aesthetic indications is a separate question. Liquid variants of fibrin-based preparations exist and blur the categories further. The taxonomy in this area is genuinely untidy, and classification schemes have been proposed in the literature specifically because of that untidiness.
Platelet rich plasma improves skin quality when injected into the dermis for aesthetic indications.
- Proposed mechanism
- Concentrated platelets release growth factors into tissue, modulating fibroblast activity and matrix production.
- What has been shown
- Platelet preparations have been studied across many indications inside and outside aesthetics, with a substantial number of small clinical studies reporting improvement in skin quality measures. Results across studies are inconsistent, and the heterogeneity of preparation protocols makes pooling difficult. Review-level assessments in this area commonly note protocol variability as a limiting factor rather than reporting a settled effect size.
- Highest level reached
- Small human studies
- Main confounders
- Preparation protocol differences between studies. Needle trauma from injection as an independent stimulus. Frequent lack of blinding and of a matched control such as saline injected identically. Short follow up.
GradeEARLY, UNREPLICATED
What would change thisTrials that report final platelet concentration, leucocyte content and activation status as composition data rather than naming a commercial kit, use a saline or vehicle control delivered by identical technique, blind the assessor, and follow up beyond the period during which needling effects alone would be expected to resolve.
The needling confound, again
Injecting anything into dermis with multiple passes is itself an intervention. The needle causes micro-injury, and micro-injury provokes the repair response that these treatments are supposed to enhance. A trial comparing PRP injection against no treatment therefore compares two things at once.
The control that resolves this is saline injected with identical technique, volume and pattern. It is not exotic and it is used in some studies. Where it is used, the interpretive burden shifts appropriately onto the preparation rather than the procedure. Where it is absent, a positive result is compatible with the needling doing the work.
| Item | Why it matters | Frequency in reporting |
|---|---|---|
| Final platelet concentration | Defines the dose of the active component | Often omitted |
| Leucocyte content | Alters the signalling profile substantially | Variably reported |
| Activation status | Determines timing of factor release | Often omitted |
| Volume and injection pattern | Determines tissue exposure and needling dose | Usually reported |
| Control arm | Separates preparation from procedure | Frequently absent or untreated control only |
| Assessor blinding | Appearance endpoints are highly susceptible to expectation | Variably applied |
Where PRP sits relative to vesicle products
It is worth comparing the two directly, because they are often presented as competitors.
PRP has a defined and simple origin, no manufacturing chain, and a large if messy clinical literature. Its weakness is that the delivered composition is unreported and variable, and that most studies cannot separate the preparation from the injection.
Vesicle preparations have a controlled manufacturing origin in principle, which allows standardisation that PRP cannot achieve, but a far smaller clinical literature, an unresolved regulatory position for injection in the UK, and the characterisation problems set out throughout our vesicle science section.
Neither of those profiles is obviously superior. They are different sets of problems, and a reader should resist the framing in which one is presented as the successor to the other. The comparison that would be informative, a head to head trial with proper controls, is not one we can point to.
What we would tell a curious reader
Ask the practitioner what protocol they use and what it produces, not which brand of kit they own. A practitioner who can describe spin parameters, leucocyte handling and activation status is treating the preparation as a variable to be controlled. A practitioner who answers only with a product name is treating it as a purchase. That distinction tells you more about the likely consistency of your treatment than any of the published literature will.
Questions readers ask
What is the difference between PRP and PRF?
PRP is prepared with anticoagulant and delivered as a liquid. PRF is prepared without anticoagulant so a fibrin clot forms, producing a matrix that holds cells and is argued to release factors over a longer period. Liquid fibrin-based variants exist and blur the boundary.
Why do PRP studies disagree with each other?
Largely because the preparations differ. Spin parameters, leucocyte content, activation status and final concentration all vary between protocols and are frequently unreported, so studies sharing a name may be studying materially different substances.
Is PRP safer than a manufactured product?
It removes concerns about animal or foreign human material and about manufacturing supply chains, because the material is the patient's own. It does not remove procedural risks such as infection or injury, and it introduces variability that a manufactured product would not have.
Does the injection itself do something?
Yes. Multiple needle passes into dermis cause micro-injury that provokes a repair response independently of what is injected. This is why a saline control delivered with identical technique is the control that matters.
Is PRP better than exosome treatment?
The two have different problem profiles rather than a clear ranking. PRP has a larger clinical literature but variable composition; vesicle products have better potential for standardisation but a smaller literature and an unresolved regulatory position for injection in the UK.