Platelet Rich Plasma Therapy

The average platelet concentration of whole blood is 200,000 per μL (normal range 150,000–350,000 per μL). Platelets are small anucleated cytoplasmic fragments of megakaryocytes that are commonly thought of as the responsible agents for hemostasis. Although the platelet is central to the coagulation cascade, it is also essential to tissue healing. The first step of the healing process is clot formation and platelet activation. After platelet activation, many growth and differentiation factors are released from the α-granules, which are storage units found in platelets. Ninety-five percent of the existing factors are released within 10 minutes of clot formation, whereas the rest of the growth factors are released as they are formed over several days.

The potential benefits of PRP are thought to rely on the intrinsic properties and interplay between the concentrated growth factors. Some of these important growth factors include platelet-derived endothelial growth factor, transforming growth factor–β, vascular endothelial growth factor, fibroblast growth factor, epidermal growth factor, and insulin-like growth factor -1. The complex interactions of these growth and differentiation factors, along with adhesive protein factors such as fibronectin and vitronectin, are what is responsible for the healing response; promoting the long regenerative process of chemotaxis, cell proliferation, removal of tissue debris, angiogenesis, extracellular matrix formation, osteoid production, and collagen synthesis.

The working definition of PRP is 1,000,000 per μL platelet count, which is five times the normal concentration found in whole blood. PRP is commonly prepared using a centrifuge. There are different types of centrifuge methods and systems and no study till date has compared the effectiveness of different PRP preparation systems or platelet concentrations against one another for any indication.

Injections are generally avoided in patients with systemic infection or skin infection over puncture site, bleeding disorders or coagulopathy and allergy to local anaesthetics or any of the medications to be administered. In addition PRP therapy should be avoided in patients with history of malignancy. Nonsteroidal antiinflammatory drugs should be avoided 2 weeks prior and at least 2 weeks after the procedure so as to not inhibit the effects of growth factors and the healing response.

The procedure is usually done on an outpatient basis. Patients need to be aware that the outcome of the procedure is variable and they may not receive the desired benefits. Similarly, they must be aware of the transient nature of the therapeutic benefits and that they may need repeated injections. A series of 3 injections with platelet rich plasma is usually recommended at 4-weekly intervals. The procedure involves the following steps:

Step1: collection of blood from the patient through venipuncture

Step2: Centrifugation to separate the whole blood into three layers: RBCs (bottom layer), platelet-poor plasma (top layer) and platelet concentrate that contains WBCs (middle layer)

Step3: Activation of platelet rich plasma with calcium and injection into the damaged tissues

Complications are rare, particularly if the injections are performed using a precise needle-positioning technique. Possible complications include bruising, infection, hematoma, nerve injury and reaction to the injectates. Infection can be avoided with appropriate aseptic precautions. Post-procedural pain flare-up may occur because the injection of PRP induces local inflammation.