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Platelets · plasma phase · preparation
Platelet-rich plasma
PRP is not a single standardized active substance, but a group of autologous blood preparations. What matters is the actual composition, the preparation protocol and the specific clinical question.
- Platelets
- Growth factors
- Centrifugation
- Leukocytes
- Fibrin
- Evidence base
- Safety
AutologousObtained from the blood of the same person in whom it is used.
No fixed formulaPreparation and cellular composition vary considerably.
RCF, not RPM aloneThe effective centrifugal force also depends on the rotor radius.
Mechanism ≠ efficacyBiological plausibility does not replace clinical evidence.
Platelet-rich plasma, usually abbreviated as PRP, is obtained from the patient’s own blood. The abbreviation stands for “Platelet-Rich Plasma”.
Compared with the original blood, PRP contains an increased concentration of platelets. These platelets are involved in haemostasis, cell communication and early repair processes. This does not automatically mean that a PRP preparation heals every injury or fully restores damaged tissue.
What is platelet-rich plasma?
PRP is a plasma fraction prepared from autologous blood. Autologous means that the blood is collected from and subsequently used in the same person.
After collection, the blood is centrifuged. Its components separate according to density. A large proportion of the red blood cells is separated from the desired plasma fraction, while platelets are concentrated in a smaller plasma volume.
Key principle
The term PRP describes a product group, not an identical substance in every setting.
Three levels that must be assessed separately
An increased platelet concentration describes only one part of the composition. Further characteristics are needed for a professional assessment.
ProductWhich cells, proteins and fibrin structures does the preparation contain?
ProcessHow were blood collection, centrifugation and fraction withdrawal performed?
ApplicationFor which indication, in which tissue and with which endpoint was it studied?
No universally valid ideal concentration
No internationally binding minimum or target concentration has been established for all PRP applications. Platelet count alone is insufficient for characterization.
What role do platelets play?
Platelets are small, anucleate components of blood. When a vessel is injured, they adhere to the damaged site, become activated and aggregate. In this way, they contribute to haemostasis and the formation of an initial wound seal.
Activated platelets adhere, aggregate and support the formation of an early clot.
Platelets store proteins and signalling molecules that can be released locally after activation.
Cytokines and growth factors can influence the activity of different cells.
Fibrin, fibronectin and other proteins can form a temporary biological matrix.
Processes under investigation include neovascularization, matrix production and modulation of inflammatory processes.
Frequently cited signalling proteins
“Self-healing” is an oversimplified description
PRP is a complex blood preparation. Its biological properties do not result from a single growth factor, but from the interaction of different cellular and plasma components.
How is PRP prepared?
Preparation begins with venous blood collection. Depending on the system, the blood is placed in a tube containing an anticoagulant to prevent premature clotting during processing.
Initial volume, tube and fill level influence the subsequent process.
The type and quantity of anticoagulant form part of product characterization.
RCF, run time, rotor design, acceleration and braking determine the separation.
The layer withdrawn and the final volume influence cell concentration and composition.
Rotational speed in revolutions per minute is not sufficient to transfer a protocol to another centrifuge. At the same RPM, different relative centrifugal forces are generated depending on the rotor radius.
Single spin and double spin are only broad process terms
Two protocols with the same number of centrifugation steps can produce different final products because of differences in RCF, run time, rotor, tube and withdrawal technique.
Why is not all PRP the same?
Two preparations may both be called PRP while differing substantially in cell content, protein composition, fibrin structure and biological activity.
Variable matrix of a PRP preparation
Composition mattersVariablePlatelet dose
What varies?
Concentration, total number and ratio to baseline blood.
Professional interpretation
A higher concentration is not automatically more favourable for every indication.
VariableLeukocytes
What varies?
Leukocyte-poor and leukocyte-rich PRP are biologically different preparations.
Professional interpretation
The desired composition depends on the tissue, indication and research question.
VariableErythrocytes
What varies?
The proportion of red blood cells depends, among other factors, on separation and the layer withdrawn.
Professional interpretation
Contamination with erythrocytes can alter biological properties and the local response.
VariableActivation and fibrin
What varies?
Activator, onset of clotting, fibrin density and release profile.
Professional interpretation
PRP and PRF should therefore not be used as interchangeable terms.
VariableFinal volume
What varies?
The same cell count may be present in different plasma volumes.
Professional interpretation
For comparisons, the total number of platelets applied is often more informative than a single concentration value.
How is PRP thought to act in tissue?
After contact with tissue or an activator, platelets may become activated. Stored signalling substances are released and coagulation processes are initiated.
Activation
Platelets respond to local tissue signals, coagulation factors or added activators.
Release
Granules release growth factors, cytokines, chemokines and other proteins.
Local signalling response
Cells in the target tissue may alter their migration, proliferation, matrix production or inflammatory response.
Clinical endpoint
Whether this leads to a measurable change in pain, function or tissue structure must be studied for each indication.
Biological plausibility is not proof of efficacy
Laboratory findings, animal models and clinical outcomes in humans answer different questions. They must not be treated as equivalent.
In which medical fields is PRP studied?
PRP and related platelet-based preparations are being investigated in numerous medical fields. The evidence differs by indication and cannot be transferred in a blanket manner.
Joints, tendons and musculoskeletal disorders
Frequently studied areas include knee osteoarthritis and individual tendinopathies. In knee osteoarthritis, meta-analyses report average changes in pain and function. This does not demonstrate complete regeneration of degraded cartilage.
indication-dependentheterogeneous protocols
Androgenetic alopecia
Some studies describe changes in hair density or hair count. Small samples, differing treatment schedules and incompletely described preparations limit the strength of the evidence.
Skin structure and scars
PRP is studied alone and in combination with microneedling, laser or other procedures. Systematic reviews assess the evidence base as methodologically inconsistent.
Different blood products, different applications
PRF membranes, autologous serum, platelet-based eye drops and injectable PRP are not identical. A result for one preparation does not automatically prove the effect of another.
Particular caution with far-reaching claims
For reproductive medicine, neurological or so-called intimate rejuvenation treatments, the evidence sometimes consists only of small studies, case series or experimental applications. Such procedures should not be presented as generally established standard therapy.
How should the evidence be interpreted?
A study result can only be interpreted meaningfully if the PRP preparation used, the indication, the comparison group and the measurement method are adequately described.
Three questions before applying findings elsewhere
- Which PRP? Platelet count, leukocytes, erythrocytes, fibrin, activation and final volume.
- For which indication? Results for knee osteoarthritis, hair loss or skin structure are not interchangeable.
- Which endpoint? Pain, function, cell count, photographic assessment and tissue structure are different outcomes.
75
randomized trials in a systematic review
Among 5,726 participants, major differences were found in preparation, concentration, application and quality control.
Baseline blood
Platelet dose
Leukocytes
Erythrocytes
Anticoagulant
Activation
RCF
Run time
Final volume
Route of administration
Comparison group
Follow-up
Is PRP therapy risk-free?
No. Obtaining the preparation from the patient’s own blood may reduce the risk of certain immune reactions. It does not make the procedure generally risk-free.
Possible adverse events
- Pain, tenderness or temporary irritation
- Swelling, redness and bruising
- Bleeding or injury to adjacent structures
- Infection or contamination during the processing chain
- Temporary worsening of symptoms
The actual risks also depend on the body region, route of administration, professional qualifications, hygiene standards and individual circumstances.
Using autologous blood does not automatically mean risk-free. Sterile processing and appropriate professional application remain key safety factors.
Whether a procedure may be considered for a specific person requires medical assessment. Relevant factors may include blood count, coagulation, acute infections, comorbidities and medication.
Why are standardized protocols important?
The term “PRP treatment” is too imprecise for reproducible documentation. Technically sound protocols should record the essential product and process characteristics.
1
Initial volume
Amount of blood collected and fill level of the tube.
2
Preparation system
Tube, additives, anticoagulant and, where applicable, separation gel.
3
Centrifugation
RCF, run time, rotor type, acceleration and braking behaviour.
4
Obtained fraction
Withdrawal layer, final volume and further processing.
5
Cell composition
Platelets, leukocytes and erythrocytes in the final product.
6
Application parameters
Volume, route of administration, number of sessions and intervals.
Comparability begins before application
Without transparent product characterization, different PRP preparations may incorrectly appear to be the same procedure in studies.
Technical context of PRP preparation
The tube system, anticoagulant, separation gel, RCF, rotor radius, run time and fraction withdrawal influence the preparation obtained. The following links are provided for technical context and do not constitute a recommendation for a specific treatment.
Technical module: plan preparation transparently
For professional users, system compatibility, the manufacturer’s protocol and documented centrifugation parameters are decisive.
PRP tubes compared
Overview of tubes with sodium citrate, separation gel or no additives, with clear differentiation between systems.
View PRP tubes →Vi PRP-PRO
Sterile borosilicate vacuum tube with 0.8 ml sodium citrate and thixotropic separation gel.
- Blood collection volume
- approx. 9 ml
- Standard protocol
- 1,200 × g · 7 minutes
- Plasma yield
- approx. 4–4.5 ml as a reference value
Hettich EBA 200 MD
Compact centrifuge with an integrated eight-place fixed-angle rotor for professional medical work environments.
- Capacity
- maximum 8 × 15 ml
- Maximum
- 6,000 rpm · 3,461 × g
- Rotor
- E3694 · fixed-angle
RCF, RPM and rotor radius
The calculator supports conversion between relative centrifugal force and rotational speed. The respective manufacturer’s specifications remain decisive.
Open RCF/RPM calculator →Centrifugation guide →
Frequently asked questions about platelet-rich plasma
Is PRP simply blood plasma?
No. Plasma is the liquid component of blood. PRP is a specifically prepared plasma fraction with a platelet concentration increased relative to the original blood.
Does PRP contain stem cells?
PRP is not stem cell therapy. Its main cellular components are platelets and, depending on the method, varying amounts of leukocytes and erythrocytes.
Does a higher platelet count mean a stronger effect?
Not necessarily. The optimal concentration depends on the indication and has not been conclusively defined for many applications. “More is better” is not a reliable general rule.
Are PRP and PRF the same?
No. Both are obtained from autologous blood, but differ in coagulation, fibrin structure, cellular composition and preparation.
Can PRP fully regenerate damaged tissue?
Such a blanket claim is not supported. Symptoms or functional measures may change in individual indications. This is not equivalent to complete anatomical restoration.
How long may an effect last?
There is no universally valid time period. Duration and extent vary according to indication, preparation, treatment plan and individual circumstances.
Professional summary
Platelet-rich plasma is not a single active substance with a fixed composition. It is a group of autologous blood preparations whose properties are determined by the baseline blood, tube system, centrifugation, withdrawal technique and further processing.
Platelets carry proteins and signalling molecules involved in haemostasis, cell communication and tissue responses. This biological basis explains why PRP is studied in different medical fields, but does not by itself prove clinical efficacy.
A sound professional assessment must therefore always clarify which PRP was prepared, for which indication it was used and which clinical endpoint was actually measured.
Sources and further reading
- The use of platelets in regenerative medicine and proposal for a new classification system: guidance from the SSC of the ISTH
- Systematic Review of Platelet-Rich Plasma in Medical and Surgical Specialties: Quality, Evaluation, Evidence, and Enforcement
- Experts Achieve Consensus on Statements Regarding PRP Treatments for Musculoskeletal Pathology
- Classification of platelet concentrates for topical and infiltrative use
- Efficacy of intra-articular PRP compared with placebo in knee osteoarthritis: systematic review and meta-analysis
- The role of platelet-rich plasma in androgenetic alopecia: a systematic review
- Platelet rich plasma for facial rejuvenation: an overview of systematic reviews
- Adverse events related to platelet-rich plasma therapy and future issues to be resolved
- The concentration of platelets in PRP does not affect pain outcomes in lateral epicondylitis: systematic review and meta-analysis
- NICE: Platelet-rich plasma injections for knee osteoarthritis – recommendations
Medical notice: This article presents biological principles, published study results and technical context for information purposes. It does not recommend for or against any specific treatment and does not replace medical examination, diagnosis or an individual treatment decision. Product references relate exclusively to technical aspects of PRP preparation.