The Science Behind Platelet Rich Plasma (PRP) Therapy

The Science Behind Platelet Rich Plasma (PRP)

Article by Corey W Hunter, MD, FIPP

Platelet-Rich Plasma (PRP) is most concisely defined as a volume of plasma that contains a concentrate of platelets (PLT) above that of baseline blood levels.[1]PRP, while considered experimental to most third-party payers, has been used for over 30 years as an aid in recovery following certain surgical, orthopedic and dental procedures with thousands of research articles having been published over that time on the safety and efficacy of its application. It is an autologous blood product which can be injected into virtually any damaged area of the body to deliver PLT-derived Growth Factors (PDGF) to promote healing.[2] Given the autologous nature of PRP, potential side effects or complications are theoretically reduced – moreover, as it is one’s own blood simply being re-administered, many view PRP as a holistic treatment methodology.

In order to understand the conceptual benefit of PRP, one must review the phases of healing. In an acute injury, platelets aggregate forming a plug at a site of injury, followed by fibrin clot. Platelets aggregate are then activated and induce inflammatory responses from monocytes, neutrophils, and lymphocytes. (2014 Golebiewska – Platelet Secretion). Degranulation of alpha granules then release seven fundamental growth factors, which initiate the healing process.1 This stage is triggered by the clotting process of blood and typically occurs within 10-15 minutes after, with more than 95% secreted within the first hour.[3] The proliferative phase begins, stimulating fibroblast to create new connective tissue (collagen), which then replaces the fibrin clot. Endothelial cells promote angiogenesis, which is required to supply nutrients to the healing region. Remodeling and scar maturation is the final stage of healing.

Interrupted wound healing occurs when there is inadequate blood supply to an injured area. This is one of the theories of chronic musculoskeletal injury. Tendons, ligaments, and joints have poor blood supply in comparison to bone, skin, and other tissues. This fact dictates their ability to heal in a timely manner and makes them prone to reinjury. PRP has been proposed as a means to “kickstart” a stalled healing mechanism in chronically inflamed tissues that have substandard blood supply. The concept is to recreate the cascade that occurs after an acute injury by artificially transplanting a platelet rich volume to an injured area with circulatory deficiency.

The popularity of PRP has been steadily growing, particularly amongst boutique and contemporary medical practices with some of the most novel applications at the time of this publication dwelling mostly within the cosmetic and elective realms (i.e. facelifts, hair regrowth, and improving one’s libido). These modalities lack evidence and typically rely mostly on anecdotal data. As it pertains to Pain Management and conventional medicine, there is a great deal of acceptance with its use for ligament, tendon, and musculoskeletal pathologies. Numerous studies have shown PRP to be effective in the treatment and management of tendonopathy and ligamentous injuries, with the most persuasive data to date being on lateral epicondylitis (tennis elbow).[4] Another popular application for PRP is osteoarthritis (OA) – particularly knee OA.[5-8]

The thinking behind PRP is that since PLT’s are the body’s nature mechanism for healing, if one were to concentrate and direct these healing agents into a particular area of injury, one could effectively focus and even accelerate the restoration process. Inherent to a concentration of PLT’s are the 7 fundamental protein growth factors proved to be actively secreted by PLT’s to initiate the healing process.1 PRP works via the activation and subsequent degranulation of the alpha granules in the PLT’s – these contain the synthesized and prepackaged growth factors.
Despite the lack of coverage by insurance companies, PRP has become a burgeoning industry with newer customized kits and more advanced equipment for obtaining PRP becoming readily available. Conventionally, PRP was created through manual laboratory preparation – standard blood collection, transferring to conical vials, centrifuging to separate the blood and extraction of the PLT-rich portion. Commercially available systems are now widely accessible with the promise of greater ease while offering more theoretical precision, higher PLT yields, and consistency.[9]

Comparing PRP systems

All PRP is not made equally