Author: Anoma Ranaweera, Medical Writer, Auckland, New Zealand, 2013.
Platelet-rich plasma (PRP), also termed autologous platelet gel, plasma rich in growth factors (PRGF), platelet concentrate (PC), is an increased concentration of autologous platelets suspended in a small amount of plasma after centrifugation and used for injection into a wound or a particular skin condition.
Blood consists of approximately 93% red blood cells (RBC), 1% white blood cells (WBC) and 6% platelets, all suspended in plasma. In platelet-rich plasma, the RBC count is lowered to 5, since they are less useful in the healing process, while the platelet count is increased to 94%.
This leads to a plasma super-rich in platelets, at a much higher percentage than would be found in normal blood concentrations with 1,000,000 platelets/mL of plasma.
PRP is ‘autologous’, meaning that it comes from the patient's own body.
Blood is withdrawn from a patient’s arm by syringe.
Platelets are probably best known as components of the blood clotting system. When injury disrupts a blood vessel and causes bleeding, platelets are activated and help with the formation of a clot that stems the flow of blood.
In addition, every platelet is also a biochemical storehouse of regulatory, signalling and growth-factor molecules that participate in recovery and healing of tissue in response to injury.
As an autologous preparation, PRP is safer to use than allogenic or homologous preparations and is free from concerns over transmissible diseases such as HIV, hepatitis, West Nile fever, and Creutzfeldt-Jakob disease.
PRP requires no special considerations regarding antibody formation, effectively preventing the risk of graft vs. host disease and leading to better acceptance by patients.
PRP effects soft tissue healing via growth factors released after platelet degranulation. These growth factors initiate and enhance physiological processes that contribute to tissue recovery and healing after injury.
Growth-factor molecules associated with platelets include:
These growth factors aid healing by:
There is accumulating evidence that PRP can help in the following skin conditions:
PRP is immunologically neutral and poses no danger of allergy, hypersensitivity or foreign-body reactions.
Sterile technique must be used at every stage of PRP preparation and application. Sterile technique is especially important if a patient has an underlying medical condition that predisposes to infection.
The PRP may be injected intralesionally or perilesionally or mixed with autologous thrombin at a 9:1 ratio, forming a platelet gel and used topically.
When administered by intradermal injection, a brief period of inflammation at wound sites may be experienced. Nerve trauma is another potential complication.
The following medical conditions are a contraindication for use of PRP:
Available data are largely based on case series. These studies have demonstrated:
Case studies conducted in a number of countries have also shown that for patients who may have moderate wrinkling due to exposure to sunlight and/or simply due to age can benefit from PRP treatment.
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