DRJ Dent Res J Dental Research Journal Dental Research Journal 1735-3327 2008-0255 Wolters Kluwer India Pvt. Ltd. India DRJ-14-427 10.4103/1735-3327.218568 Letter to Editor Plasma rich in growth factors in dogs: Two sides of the same coin Anitua Eduardo Prado Roberto Orive Gorka Regenerative Medicine Department, BTI - Biotechnology Institute; University Institute for Regenerative Medicine and Oral Implantology - UIRMI (UPV/EHU-Fundación Eduardo Anitua), Vitoria, Spain Regenerative Medicine Department, BTI - Biotechnology Institute; University Institute for Regenerative Medicine and Oral Implantology - UIRMI (UPV/EHU-Fundación Eduardo Anitua), Vitoria, Spain Regenerative Medicine Department, BTI - Biotechnology Institute; University Institute for Regenerative Medicine and Oral Implantology - UIRMI (UPV/EHU-Fundación Eduardo Anitua), Vitoria, Spain Address for correspondence:Gorka Orive, BTI - Biotechnology Institute, Jacinto Quincoces Kalea, 39, 01007, Vitoria, Spain gorka.orive@ehu.es Nov–Dec 2017 14 6 427 428 Copyright: © Dental Research Journal 2017

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<p>Dear Editor,</p> <p>We have read with interest the recent article in Dental Research Journal entitled “Socket preservation using freeze-dried bone allograft (FDBA) with and without plasma rich in growth factors (PRGF) in dogs” by Samandari et al. <sup> <xref ref-type="bibr" rid="ref1">1</xref> </sup>The aim of this study was to compare the effect of the combined use of PRGF and FDBA on bone formation versus FDBA alone or control group filled with blood clot. This research was carried out in experimental sockets in four dogs.</p> <p>We would like to make some considerations regarding the use of PRGF in dogs. In the materials and methods section of this paper, Samandari et al. describe the preparation of PRGF in dogs using BTI-Biotechnology Institute's Technology. The authors provide centrifugation conditions of 2000 rpm for 8 min. In addition, they divide the plasma column into three fractions and use the one closest to the leukocytes (fraction 3).</p> <p>First, we would like to point out that the centrifugation parameters referenced by the authors are not accurate, since the centrifuge PRGF system IV is a medical device that presents fixed centrifuge programs, and their modification by the user is not possible. In addition, the authors separate three fractions in plasma despite it has been extensively shown in humans that three fractions are not necessary since just the two fractions protocol presents a similar biological effect. <sup> <xref ref-type="bibr" rid="ref2">2</xref> </sup>Furthermore, the protocol for humans has recently evolved, and in the light of scientific evidence, it has been reduced both the amount of anticoagulant and the activator. <sup> <xref ref-type="bibr" rid="ref3">3</xref> </sup></p> <p>Second, we do not observe that the authors have performed a characterization of the product, nor do they refer to another previous publication that has carried out the PRGF characterization in dogs. We definitely believe that it is fundamental to know the product that is applied in the treatment.</p> <p>To the best of our knowledge, there are at least another three studies <sup> <xref ref-type="bibr" rid="ref4">4</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref5">5</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref6">6</xref> </sup>in which PRGF has been applied in dogs during 2016, in addition to the cited study. <sup> <xref ref-type="bibr" rid="ref1">1</xref> </sup>These studies use different protocols for obtaining PRGF but have in common that none of them characterizes the PRGF obtained in dogs. Our aim here is not to criticize the design or the conclusions of the different investigations, but only to highlight the great variability of protocols used and, especially the lack of characterization, reported in those studies. This is, especially, relevant and should be taken into account when comparing the results of different studies and thus avoiding the irreproducibility of many of them or when the advances found in animal experimentation are extrapolated to humans. <sup> <xref ref-type="bibr" rid="ref7">7</xref> </sup>, <sup> <xref ref-type="bibr" rid="ref8">8</xref> </sup>We encourage the different authors to carry out the characterization of the PRGF or to present it in their publications if they have already performed it.</p> <p>Platelet-rich plasma (PRP) was originally developed in humans, and then, its use has spread in veterinary. It would be desirable not to fail again on mistakes of the past and try to achieve a standardization of veterinary products. <sup> <xref ref-type="bibr" rid="ref9">9</xref> </sup>As any biomedical product, PRGF technology is permanently evolving, but it preserves a clear and consistent philosophy: it is a type of PRP obtained from small volumes of blood through a single centrifugation and subsequent fractionation of the plasma. <sup> <xref ref-type="bibr" rid="ref10">10</xref> </sup>It is moderately enriched in platelets and does not contain leukocytes or erythrocytes (classified as pure-PRP). In addition, the activation is performed solely with calcium chloride. <sup> <xref ref-type="bibr" rid="ref10">10</xref> </sup>All these premises must be followed to affirm that PRGF technology is being used.</p> <p>As it is already known, the blood of each animal species has different characteristics that do not necessarily coincide with the human one. <sup> <xref ref-type="bibr" rid="ref11">11</xref> </sup>Recently, we assayed the human PRGF protocol in a model of peri-implant gap bone in rabbits but having previously characterized the rabbit-based PRGF and thus observing that it was similar to the human one. <sup> <xref ref-type="bibr" rid="ref12">12</xref> </sup>However, in another research carried out in a sheep model of nerve regeneration, the PRGF protocol was adapted to obtain a PRGF with similar characteristics to those of humans. <sup> <xref ref-type="bibr" rid="ref13">13</xref> </sup></p> <p>The translation of PRGF from humans to dogs is dealing with two sides of the same coin. On the one side, human and dogs are different species; but on the other side, we need to properly transfer and translate our 20 years' experience in humans to the treatment of canine injuries. In summary, we encourage researchers to use PRGF technology both in research with animal models as well as in veterinary treatments but always characterizing the obtained product since we should not leave our knowledge to get lost in translation.</p> <p>Financial support and sponsorship</p> <p>Nil.</p> <p>Conflicts of interest</p> <p>E. A. is the Scientific Director of and R. P. and G. 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