The biology
Platelets store growth factors including PDGF, TGF-beta, VEGF and EGF in their alpha granules. On activation they release these locally, initiating the signalling that recruits cells and builds new matrix during repair.
PRP therapy exploits that mechanism by concentrating platelets from a patient's own blood and delivering a high local dose to tissue where repair has stalled.
Preparation
A small blood volume is drawn into an anticoagulated tube or kit and centrifuged to separate red cells, plasma and the platelet layer. The platelet-rich fraction is collected and injected, usually within the same appointment.
Protocols differ in spin speed and duration, whether leucocytes are included, and how the layer is harvested. Those choices change platelet yield by several-fold, which is the main reason clinical results vary between studies.
Why closed systems matter
Open pipetting exposes plasma to room air and depends on operator technique. Closed single-use devices separate inside the kit, reducing contamination risk and producing a more reproducible concentration between operators and sessions.
For a therapy whose dose is the concentration delivered, reproducibility is not a convenience feature — it is the difference between comparable and non-comparable treatments.
Clinical use
PRP is used in tendinopathy and osteoarthritic joint injection, as an adjunct in chronic and post-surgical wounds, and in dermatological and hair-restoration protocols. Evidence strength varies by indication, and patients should be counselled accordingly.
This article is general educational information for healthcare professionals and is not clinical advice or a treatment recommendation. Always refer to the current instructions for use and local clinical guidance.