Page 86 - Athletic Health Handbook
P. 86
Preparation and, thus, slows platelet activation so components of articular cartilage
that the platelets release growth factors repair. Finally, Fukumoto et al9
Platelet-rich plasma is made from slowly over a seven day period.3 demonstrated that IGF-I has a
anti-coagulated blood. Citrate is synergistic effect with TGF-beta
first added to whole blood to inhibit Platelet Biology promoting mesenchymal stem
the clotting cascade. The blood then cell chondrogenesis.
undergoes two centrifugation steps: Platelets are cytoplasmic fragments of
Ⅲ Separation of the red and white megakaryocytes and have no nuclei. There have also been several in
They do contain organelles and vivo animal studies demonstrating
blood cells from the plasma granules, including the important the potential benefits of PRP and its
and platelets alpha-granules. Alpha-granules components on soft tissue healing.
Ⅲ Further concentration contain more than 30 growth Aspenberg and Virchenko10 found
of the platelets factors fundamental to hemostasis that a platelet concentrate injected
This second centrifugation and tissue healing. Important into the hematoma six hours after
produces the PRP which then needs growth factors in the alpha-granules the creation of an Achilles tendon
to be clotted to allow for platelet include platelet-derived growth defect in a rat resulted in increased
activation and the release of the factor (PDGF), transforming growth tendon callus strength and stiffness
growth factors. Two main activation factor-beta (TGF-beta), vascular compared to controls. Kajikawa et al11
techniques exist: endothelial growth factor (VEGF), showed that the injection of PRP
Ⅲ The use of bovine thrombin to epidermal growth factor (EGF), and into rat patellar tendons resulted in
activate the clotting mechanism insulin-like growth factor 1 (IGF-1).4 increased levels of types I and III
after the second centrifugation PDGF stimulates cell replication, collagen and macrophages, which
Ⅲ The use of CaCl2 during the angiogenesis, and fibroblasts. is indicative of tendon repair and
second centrifugation step VEGF promotes angiogenesis remodeling. In a porcine model,
to initiate the formation of and neovascularization. TGF-beta Murray et al12 demonstrated that
autogenous thrombin from regulates fibroblasts and collagen transected ACLs treated with a
prothrombin in the plasma. production. IGF-1 stimulates collagen-PRP hydrogel at the
myoblasts and fibroblasts and transaction site healed with higher
Vial of blood after the first centrifugation mediates skeletal muscle repair and load at yield, maximum load,
process. The “buffy coat” contains growth. EGF stimulates mesenchymal and linear stiffness at four weeks
the platelet-rich plasma. and epithelial cells and potentiates compared to controls after suture
other growth factors. All of these repair of the ligaments. In a goat
The first technique results in activities contribute to the repair of model, Spindler et al13 found that
the release of 70 percent of the tendon, skeletal muscle, and bone. application of a collagen-platelet
pre-synthesized growth factors aggregate around a patellar tendon
within 10 minutes and 95 percent Laboratory Studies autograft reconstruction resulted
within one hour.1 The platelets then in improvements in knee laxity
continue to synthesize and secrete Several cell culture studies have compared to grafts treated in a
additional factors for the remainder of demonstrated the enhancement collagen scaffold alone. Finally,
their lifespan (8–12 days). The second properties of PRP and its constituents. in a canine model, Yasuda et al14
mechanism results in the formation De Mos et al5 and Anitua et al6 noted showed that beagles undergoing ACL
of a dense fibrous matrix during the a dose-related increase in the number reconstruction with autogenous
second centrifugation phase which of tenocytes and increase in collagen patellar tendon grafts treated with a
entraps the intact platelets. This, in production in child and young adult fibrin sealant containing TGF-B and
turn, results in the production of human tenocytes cultured with PRP. epidermal growth factor (EGF) had
only a small amount of thrombin Similarly, Klein et al7 found increased less anterior-posterior knee translation,
collagen production by rabbit foot greater graft cross-sectional area,
tenocytes grown with TGF-beta, a and greater graft stiffness and load
key component of PRP. Also, Barry at failure than those beagles whose
et al8 have shown that mesenchymal grafts were not treated or those just
cells cultured with TGF-beta produced treated with fibrin without the
significantly more proteoglycans growth factors.
and type II collagen which are key

   81   82   83   84   85   86   87   88   89   90   91