Platelet Rich Plasma (PRP):
working definition of platelet rich plasma (PRP) refers to a 5 ml volume of plasma that contains a concentration of 1,000,000-platelets/micro
liter 1. This definition is based on the scientific proof of the concentration considered optimal for bone and
soft tissue healing enhancement. PRP must be distinguished from platelet concentrate, which is a pure composition of platelets
without any plasma, and thus doesn’t clot2, 3. The process of processing PRP from blood involves a double
centrifugation technique: the hard spin and soft spin. The first spin also called as hard spin separates the red blood cells
(RBC) from plasma, resulting in a platelet poor plasma (PPP) media containing the platelets, the white blood cells (WBC) and
occasional RBCs. The second spin also known as the soft spin produces PRP from PPP by increasing the platelet concentration.
This PRP is a combination of both a fresh clot and the supernatant. The PRP can be applied in various forms: as biologic membranes,
mixed with the bone graft, sprayed on soft tissue or applied on the surface of the graft. The important precaution that should
be taken with use of PRP is that clotting of PRP should be done only at the time of use as the clotting activates the platelets,
which begin to secrete the growth factors almost immediately. As much as 70% of the stored growth factors are released in
first 10 min and the rest almost completely in first hour.
contains seven known growth factor: platelet derived growth factor aa (PDGF aa), PDGF bb, PDGF ab, Transforming growth factor
(TGF) beta 1, TGF beta 2, vascular endothelial growth factor (VEGF), and epithelial growth factors. PRP contains these seven
growth factor within a normal clot acting as carrier. The clot in turn is composed of fibrin, Fibronectin and vitronectin4,
which help in cell migration, osseointegration and wound epithelialization. The growth factors present in PRP are proteins
that serve as signaling molecules for target cells and orchestrate a large number of physiologic events including cell division,
matrix synthesis and tissue differentiation. These agents have been also shown to be involved in the reparative process like
inhibit apoptosis and promote proliferation of cells in particular the capillary endothelium and arterial smooth muscles by
activating the survival signal pathways 8 and is also chemo attractant to macrophages and fibroblasts9-11.
It has been shown to act in syngerism with IGF I to promote mitogenesis of mesenchymal cells.12. Insulin like growth
factors I and II stimulate cell differentiation13. Epidermal growth factors along with PDGF have shown to increase
DNA synthesis and cell replication14. TGF Beta has shown to increase the cell differentiation15 and
has a direct stimulatory effect on bone collagen synthesis, while the fibro blast growth factor serve to initiate neo angiogenesis16
which is essential for new bone formation.
beneficial effect of PRP have been reported both in vitro as demonstrated by increased mitotic activity in osteoblasts like
cells17 and in vivo in sinus surgies, alveolar ridge augmentation and periodontal surgeries18-20. Platelet
derived growth factors were also reported to be secreted by platelets during the early phases of the fracture healing in mice
and humans21, 22 . Marx et al in 1998 proposed that the local application of growth factors in form of platelet
rich plasma (PRP) enhances the maturation of bone graft.1 Monoclonal antibody assessment of cancellous cellular
bone marrow grafts have shown mesenchymal cells of the graft are responsive to the growth factors and addition of platelet
rich plasma containing the growth factors increased the radiographic maturation rates 1.62 to 2.16 times that of graft alone
in a series of maxillofacial reconstruction23 Pre clinical animal studies also showed them to be effective in healing
the tibial osteotomy site in rabbits24.
How ever similar results were not replicated in humans where platelet
gel (AGF) alone or in combination with autologus bone graft failed to increase the fusion rates. In a retrospective study
of 76 consecutive patients who underwent one to three level instrumented posterior lumbar fusions using autologus iliac crest
bone graft mixed with AGF, the fusion rates were lower compared to the control group in which only autologus bone graft was
used.25 Other series evaluating the effect of AGF in transforaminal interbody fusions also failed to demonstrate
any clinical effect26, 27. Weiner and walker showed a detrimental effect of AGF on intertransverse arthrodesis
when combined with autologus bone graft28. In maxillofacial surgery too, histo-morphometric analysis of the effect
of PRP alone failed to demonstrate any positive effect of PRP on augmentation of bone formation on organic bovine bone or
autologus bone graft in bone defects in maxillofacial region.29
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JE, Georgeff KR. Platelet rich plasma : growth Factor enhancement for bone garfts. Oral surg oral med oral pathol oral radiol
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et al. The effect of platelet release on wound healing in animla models. J Am Acad Dermatol 22:781-791, 1990.
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Early growth responsive- 1- dependent manganese superoxide dismutase gene transcription mediated by platelet derived growth
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E:. Early induction of plateletderived growth factors and ligands and receptors in acute renal allograft rejection. Transplantation
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beta enhances fracture healing in rabbit tibiae. Acta Orthop Scand 64:533-556, 1993.
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D:. Platelet derived growth factor and transforming growth factor beta in invertebrate immune and neuroendocrine interactions:
another sign of conservation in evolution. Comp Biochem C Toxicol Pharmacol 129:295-306, 2001.
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WJ. Dual control of cell growth by somatomedins and platelet derived growth factor. Proc Natl Acad Sci USA 76:1279-1283, 1979.
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II promoter expression in cultured rodent osteoblasts and adult rat bone. Endocrinology 139:2287-2292, 1998.
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sphingosine kinase activity by platelet derived growth factor. FEBS Lett. 503:85-90, 2001.
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16. Plandit AS FD, Caulfield J, et al. Stimulation of angiogenesis
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Reichert TE, wagner W. Wachstumstimulation von humanen osteoblastnahnlichen zellen durch Thrombozytenkonzentrate in vitro.
Mund keifer Gesichtshir. 6:168-174, 2002.
18. Kassolis JD RP, Reynolds
MA. Alveolar ridge and sinus augmentation utilising platelet rich plasma in combination with freeze dried bone allograft:
Case series. J Periodontol 71:1654-1661., 2000.
19. Anitua E. Platelet rich plasma in growth factors: preliminary
results off use in the preperation of future sites for implants. Int J oral Maxillofac Implants 14:529-535, 2000.
20. Vojislav l CP, Wein lander
M, Vasilic N, Kenney EB. Comparison of platelet rich plasma, bovine porous bone mineral, and guided tissue regeneration versus
platelet rich plasma and bovine porous bone mineral in the treatment of intrabony defects: a reentry study. J Periodontol
21. Andrew JG HJ, Freemont
AJ, Marsh DR. Platelet derived growth factor expression in normally healing human fractures. Bone 16:455-460, 1995.
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Georgeff KR. Platelet rich plasma: Growth factor enhancement for bone grafts. Oral surgery oral medicine oral pathology oral
radiology and endodontics 85:638-646, 1998.
24. Nash TJ HC, Martin C, Steele J, Jhonson KA, Hicklin DJ.
Effect of platelet derived growth factor on tibial osteotomies in rabbit. Bone 5:203-208, 1994.
25. Yoram Anekstein Sg, Ronaldo Puno, Leah Carreon. Platelet
gel (AGF) fails to increase fusion rate. The spinal Journal 3s:89s, 2003.
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spinal fusions. J Spinal Disord Tech 17:380-384, 2003.
27. Hee HT MM, Holt RT, Myers L:. Do autologus growth factors
enhance transforaminal lumbar interbody fusion?. European spine Journal 12:400-407, 2003.
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in lumbar intertransverse fusions.[see comment]. Spine 28:1968-1970, 2003.
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Miller, sandra Freitag, David C. Rueger, Yahya Acil, Hendrix Terheyden. Bone Formation in the presence of platelet rich plasma
vs. bone morphogenic protein -7. Bone 34:80-90., 2004.