Note: To access the videos accompanying this report, visit the March issue of Arthroscopy at www.arthroscopyjournal.org.
Arthroscopy: The Journal of Arthroscopic & Related Surgery
Current Concepts With Video IllustrationsPlatelet-Rich Plasma: A Milieu of Bioactive Factors
Section snippets
PRP Production
PRP is a plasma suspension that contains all components of whole blood in varying amounts (Videos 1 and 2, available at www.arthroscopyjournal.org). According to the Red Cross, PRP by definition contains a minimum of 200,000 platelets/μL. Preparation processes take advantage of differing density gradients of the components in blood to concentrate platelets. Centrifugation of whole venous blood containing an anticoagulant results in a plasma supernatant with a gradient of cellular concentration.
Platelets
Platelets (thrombocytes) range from 2 to 3 μm in size while circulating for 7 to 10 days at concentrations of 150 to 400 × 103/μL. They are anucleate cytoplasmic fragments of multinucleated megakaryocytes located in bone marrow. Platelets are most often thought of primarily for their hemostatic and coagulation functions; however, proteomic studies have shown that platelets contain over 800 proteins with numerous post-translational modifications, such as phosphorylation, resulting in over 1,500
Plasma
Plasma is defined as the yellow-colored liquid component of blood in which blood cells are suspended. Approximately 200 proteins have been documented in plasma, including albumin, immunoglobulins, complement, and clotting factors.53 Because plasma transiently contains many proteins released from cells and metabolic processes throughout the body, the presence of as many as 679 proteins has been documented.54 Biomarkers of bone turnover can be found in plasma as well, including osteocalcin and
Leukocytes
Mammalian leukocytes are classified as granulocytes (neutrophils, eosinophils, and basophils) or mononuclear cells (lymphocytes and monocytes or macrophages). Phagocytic cells such macrophages are essential to the in vivo healing process.66 A murine model was used to show that macrophages were essential for debridement of damaged ligamentous tissue and for cytokine release that mediates the repair process.66 The presence of leukocytes can result in proinflammatory cellular signaling and local
Erythrocytes
The centrifugation process used to generate PRP typically reduces or eliminates the presence of erythrocytes (red blood cells). Because some red blood cells are often present, they are worth discussing. The main function of erythrocytes is to carry oxygen, which is essential for tissue repair. As such, red blood cells lack most cellular organelles, including a nucleus, endoplasmic reticulum, and mitochondria. They contain about 750 proteins compared with the estimated 20,000 or more proteins of
Clinical Relevance
Knowing the components of PRP being used will help elicit the important factors in various applications of this regenerative therapy (Table 4). As an example, 5 recent articles in Arthroscopy evaluated anterior cruciate ligament reconstruction and compared PRP-augmented procedures with controls.77, 78, 79, 80, 81 Magnetic resonance imaging evaluation times ranged from 3 to 24 months postoperatively, and results of these trials were variable. Several letters to the editor and the authors'
Conclusions
PRP is a useful regenerative therapy to address many musculoskeletal injuries. It is important to understand that PRP is more than just platelets and that it contains many bioactive factors that act in anabolic, catabolic, proinflammatory, and anti-inflammatory pathways. Some components are also involved in the modulation of the immune response. The precise combination and concentration of platelets, leukocytes, and other plasma components best for musculoskeletal healing are not presently
References (85)
- et al.
Platelet-rich plasma concentrate to augment bone fusion
Foot Ankle Clin
(2010) - et al.
Platelet alpha-granules: Basic biology and clinical correlates
Blood Rev
(2009) - et al.
The use of platelet-rich plasma in arthroscopy and sports medicine: Optimizing the healing environment
Arthroscopy
(2010) - et al.
Evaluation of factors that can modify platelet-rich plasma properties
Oral Surg Oral Med Oral Pathol Oral Radiol Endod
(2008) - et al.
Inhibition of oxidative-stress-induced platelet aggregation by androgen at physiological levels via its receptor is associated with the reduction of thromboxane A2 release from platelets
Steroids
(2007) - et al.
Propofol: A review of its non-anaesthetic effects
Eur J Pharmacol
(2009) - et al.
A review of the effects of insulin-like growth factor and platelet derived growth factor on in vivo cartilage healing and repair
Osteoarthritis Cartilage
(2006) - et al.
Temporal and spatial expression of TGF-beta1 in an Achilles tendon section model after application of platelet-rich plasma
Foot Ankle Surg
(2010) - et al.
Does a single application of PRP alter the expression of IGF-I in the early phase of tendon healing?
J Foot Ankle Surg
(2011) - et al.
Proteomic analysis of platelet alpha-granules using mass spectrometry
J Thromb Haemost
(2007)
Potential roles of growth factor PDGF-BB in the bony repair of injured growth plate
Bone
5-HT and bone biology
Curr Opin Pharmacol
Insulin-like growth factor-I improves cellular and molecular aspects of healing in a collagenase-induced model of flexor tendinitis
J Orthop Res
Neutrophils, from marrow to microbes
Immunity
Neutrophil granules and secretory vesicles in inflammation
Microbes Infect
Granules of the human neutrophilic polymorphonuclear leukocyte
Blood
In-depth analysis of the membrane and cytosolic proteome of red blood cells
Blood
Nitric oxide inhibition of IGF-1 stimulated proteoglycan synthesis: Role of cGMP
J Orthop Res
Nitric oxide decreases IGF-1 receptor function in vitro; glutathione depletion enhances this effect in vivo
Osteoarthritis Cartilage
Effects of platelet concentrate and a bone plug on the healing of hamstring tendons in a bone tunnel
Arthroscopy
Comparison of magnetic resonance imaging findings in anterior cruciate ligament grafts with and without autologous platelet-derived growth factors
Arthroscopy
Ligamentization of tendon grafts treated with an endogenous preparation rich in growth factors: Gross morphology and histology
Arthroscopy
Magnetic resonance imaging evaluation of the integration and maturation of semitendinosus-gracilis graft in anterior cruciate ligament reconstruction using autologous platelet concentrate
Arthroscopy
Concerns about the effects of platelet concentrate
Arthroscopy
Poor standardization in platelet-rich therapies hampers advancement
Arthroscopy
But he isn't wearing anything at all! “The Emperor's New Clothes” (Kejserens Nye Klaeder by Hans Christian Andersen)
Arthroscopy
Growth factor confusion
Arthroscopy
Chronic wounds treated with a physiologically relevant concentration of platelet-rich plasma gel: A prospective case series
Ostomy Wound Manage
Is platelet concentrate advantageous for the surgical treatment of periodontal diseases?A systematic review and meta-analysis
J Periodontol
What's new in orthopaedic research
J Bone Joint Surg Am
Platelet rich plasma (PRP) enhances anabolic gene expression patterns in flexor digitorum superficialis tendons
J Orthop Res
Platelet-rich plasma on calcium phosphate granules promotes metaphyseal bone healing in mini-pigs
J Orthop Res
Platelet-rich plasma treatment for ligament and tendon injuries
Clin J Sport Med
Antimicrobial activity of platelet-leukocyte gel against Staphylococcus aureus
J Orthop Res
Positive effect of an autologous platelet concentrate in lateral epicondylitis in a double-blind randomized controlled trial: Platelet-rich plasma versus corticosteroid injection with a 1-year follow-up
Am J Sports Med
Use of platelet rich plasma to treat plantar fasciitis: Design of a multi centre randomized controlled trial
BMC Musculoskelet Disord
Comparison of surgically repaired Achilles tendon tears using platelet-rich fibrin matrices
Am J Sports Med
Temporal growth factor release from platelet-rich plasma, trehalose lyophilized platelets, and bone marrow aspirate and their effect on tendon and ligament gene expression
J Orthop Res
Shedding light in the controversial terminology for platelet-rich products: Platelet-rich plasma (PRP), platelet-rich fibrin (PRF), platelet-leukocyte gel (PLG), preparation rich in growth factors (PRGF), classification and commercialism
J Biomed Mater Res A
Platelet rich plasma injection grafts for musculoskeletal injuries: A review
Curr Rev Musculoskelet Med
Does it matter which platelet-rich plasma we use?
Equine Vet Educ
Platelet products prepared by different methods of sedimentation undergo platelet activation differently during storage
Transfusion
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The authors report that they have no conflicts of interest in the authorship and publication of this article.