J Oral Maxillofac Surg 62:489-496, 2004 Platelet-Rich ...

1 CLINICAL CONTROVERSIES IN ORAL AND MAXILLOFACIAL SURGERY: PART TWOJ Oral Maxillofac Surg62:489-496, 2004 Platelet-Rich plasma : evidence to SupportIts UseRobert E. Marx, DDS* Platelet-Rich plasma (PRP) is an autologous concentra-tion of human platelets in a small volume of , the term PRP is preferred to autologousplatelet gel, plasma - rich growth factors (PRGFs), or amere autologous platelet concentrate. Because it is aconcentration of platelets, it is also a concentration ofthe 7 fundamental protein growth factors proved tobe actively secreted by platelets to initiate all woundhealing. These growth factors include the 3 isomeresof platelet -derived growth factor (PDGF , PDGF ,and PDGF ), 2 of the numerous transforminggrowth factors- (TGF 1 and TGF 2), vascular endo-thelial growth factor, and epithelial growth factor.

2 Allof these growth factors have been documented toexist in ,2 Because these concentrated plate-lets are suspended in a small volume of plasma , PRP ismore that just a platelet concentrate; it also containsthe 3 proteins in blood known to act as cell adhesionmolecules for osteoconduction and as a matrix forbone, connective tissue, and epithelial cell adhesion molecules are fibrin itself, fi-bronectin, and development via centrifugation has beengreatly simplified so that it can be used in the officesetting as well as the operating room. However, thecentrifugation process must be sterile and preciselysuited to platelet separation from red blood cells andtheir sequestration in high concentrations withoutlysing the platelets or damaging them so that they nolonger can actively secrete their growth , not all currently marketed PRP devices areequal; some do not concentrate viably active plateletsin sufficient numbers to produce a healing enhance-ment.

3 This has led to and explains most of the criti-cisms regarding the efficacy of PRP. In addition, therehave been some research efforts to study PRP inanimal models that have a blood volume that is toosmall to produce PRP; therefore, these studies haveused donor blood. This of course is homologous, notautologous, and therefore is not true PRP. The use ofdonor animal blood platelets imparts an overt im-mune reaction and leads to false-negative results thatmay falsely be ascribed to PRP is always autologous and is not homolo-gous. An example of this confusion is the use oflyophilized donor platelets. Homologous platelets arenot viable and could not possibly secrete bioactivegrowth factors.

4 Homologous platelets are also anti-genic due to their abundance of cell , antiplatelet antibodies could develop fromthis product and second set reactions would substances offer no useful comparison to autologous PRP, clinicians must read theliterature and assess the results of studies relating toPRP as to whether a Food and Drug Administration(FDA)-cleared device produced the PRP and whetherplatelet concentrations and growth factors were doc-umented. At the time of this writing, only 2 officedevices used to develop PRP have been cleared by theFDA (Smart PReP; Harvest Technologies Inc, Ply-mouth, MA; and the platelet Concentration CollectionSystem [PCCS]; 3i Implant Innovations, Inc, WestPalm Beach, FL).

5 2A study conducted in our laborato-ries and repeated by the Center for Blood Research inBoston, MA, indicated that of all of the devices tested,these 2 FDA-cleared PRP devices produced the great-est platelet concentrations and, most important, re-lease of a therapeutic level of bioactive growth factors(Tables 1 and 2). Studies suggesting that there is nobenefit from PRP can often be traced to poor-qualityPRP produced by inadequate devices. Studies byWeibrich and Klies,3for instance, documented theinadequacy of such devices. They found this oneparticular device to be deficient in developing thera-peutic levels of platelets compared with other devicesand was not cleared by the Certification Europe orga-nization, which is the European counterpart to the US*Professor of Surgery and Chief, Department of Oral and Maxil-lofacial Surgery, University of Miami School of Medicine and Jack-son Memorial Hospital, Miami, correspondence and reprint requests to Dr Marx: De-partment of Oral and Maxillofacial Surgery, University of MiamiJackson Memorial Hospital, 9380 SW 150th St, Suite 190, Miami, FL33157.

6 E-mail: 2004 American Association of Oral and Maxillofacial Surgeons0278-2391/04/6204-0018$ Our own testing concurs with , the clinician must look at such PRP-nega-tive literature to assess whether PRP with therapeuticplatelet levels was really prudent clinician who uses PRP or the clinicianjudging whether the healing enhancement of PRPwould offer a benefit to his or her patients shouldassess the literature with scientific scrutiny and askthe following critical Does PRP Work?PRP works via the degranulation of the granulesin platelets, which contain the synthesized and pre-packaged growth factors. The active secretion ofthese growth factors is initiated by the clotting pro-cess of blood and begins within 10 minutes afterclotting.

7 More than 95% of the presynthesized growthfactors are secreted within 1 , PRPmust be developed in an anticoagulated state andshould be used on the graft,flap, or wound, within 10minutes of clot initiation. Studies that have not usedanticoagulated whole blood, which is then clotted toactivate the PRP, are not really studies of PRP andtherefore are misleading. Related to this, PRP hasbeen shown to remain sterile and the concentratedplatelets viable for up to 8 hours once developed inthe anticoagulated state and placed on a sterile surgi-cal table. Like most growth factors such as bonemorphogeneic protein (BMP) and similar to collagen,the growth factors within the granules of plateletsare incomplete because they must be soluble.

8 As theclotting process activates the platelets, the growthfactors are secreted from the cell through the cellmembrane. In this process, the granules fuse to theplatelet cell membrane where the protein growthfactor is completed to a bioactive state by the additionof histones and carbohydrate side chains to theseproteins. Therefore, platelets damaged or renderednonviable by PRP processing will not secrete bioac-tive growth factors and may result in secreted growth factors immediately bind tothe external surface of cell membranes of cells in thegraft,flap, or wound via transmembrane have shown that adult mesenchymal stemTable 2. platelet YIELDS PER DEVICED eviceMean PRPV olume(mL)Mean PlateletConcentration 103 PlateletYield (%)Increase AboveBaseline (%)Laboratory Centrifuge (Anitua Protocol) 12935 168190 Laboratory Centrifuge (Landesberg Protocol) 14130 Sealed Technology Centrifuge* 26739 Surgical 24533 Curasan 19229 28461 Technologies SmartPReP ,086 22762 *Clinaseal Sealed Technology Centrifuge; Salvin Dental Specialties Inc, Charlotte, NC.

9 ACE Surgical, Brockton, MA. AG Curasan, Kleinostheim, 1. GROWTH FACTOR YIELDS PER DEVICED eviceMean PRPV olume(mL)PDGF- (ng/mL)TGF- (ng/mL)Laboratory Centrifuge (Anitua Protocol) Centrifuge (Landesberg Protocol) Sealed Technology Centrifuge* Surgical Curasan 27144 Technologies SmartPReP *Clinaseal Sealed Technology Centrifuge; Salvin Dental Specialties Inc, Charlotte, NC. ACE Surgical, Brockton, MA. AG Curasan, Kleinostheim, support OF Platelet-Rich plasma cells, osteoblasts,fibroblasts, endothelial cells, andepidermal cells express the cell membrane receptorsto growth factors in transmembrane re-ceptors in turn induce an activation of an endogenousinternal signal protein, which causes the expressionof (unlocks) a normal gene sequence of the cell suchas cellular proliferation, matrix formation, osteoidproduction, collagen synthesis, etc.

10 The importanceof this knowledge is that the PRP growth factorsnever enter the cell or its nucleus, they are not mu-tagenic, and they act through the stimulation of nor-mal healing, just much faster. Therefore, PRP has noability to induce tumor formation and has never ,5 After the initial burst of PRP-related growth factors,the platelets synthesize and secrete additional growthfactors for the remaining 7 days of their life the platelet is exhausted and dies off, the mac-rophage, which has arrived in the region via thevascular in-growth stimulated by the platelets, as-sumes the function of wound healing regulation bysecreting some of the same growth factors as well asothers.