The reproducibility of human platelet-rich plasma with respect to platelet counts and putative cytokine levels

Abstract

Statement of the Problem: Platelet-rich plasma (PRP) has been advocated as a beneficial adjunct to bone grafting procedures in the maxillofacial region. Many questions remain unanswered, however, concerning PRP efficacy when used in combination with bone grafting. This study sought to establish what range of PRP concentrates and cytokine levels could predictably be obtained from healthy volunteers using a commercially available automated centrifuge designed specifically for the collection of PRP. Materials and Methods: Twenty-four blood samples were collected from 15 male and 9 female healthy volunteers. All samples (60 mL for females, 55 mL for males) had a 500 microliter aliquot removed for determination of baseline complete blood counts. A SmartPReP machine (Harvest Technologies) was used according to the manufacturer’s instructions to prepare the PRP. Aliquots of platelet-poor plasma (PPP), PRP, and whole blood were run on the Coulter STKS (Coulter Corporation). Eleven PRP samples underwent cytokine analysis. Levels of platelet derived growth factor AB (PDGF-AB) were determined using a Human PDGF-AB Quantikine Colorimetric Sandwich ELISA kit (R&D Systems). Transforming growth factor beta 1 (TGF-β1) levels were determined using a Human TGF-β1 Colorimetric Sandwich ELISA kit (YesBiotech). Method of Data Analysis: All quantitative measurements were described using summary statistics. Scatterplots and Spearman rank correlation coefficient were used to identify relationships between 1) platelet counts in whole blood and PRP, and 2) growth factor levels and platelet counts. Student’s t tests were also performed to identify any differences in test groups. Results: Analysis of PRP samples showed an average platelet increase of 396%. Significant variation did exist, however, with platelet counts ranging from 363 × 109 cells/L to 1,900 × 109 cells/L. Females did appear to produce a more concentrated PRP product, but this was not statistically significant. An association was demonstrated between the volunteer’s whole blood platelet count and that of the PRP. A high degree of variability was also noted when examining the results of the initial cytokine release levels of PRP and PPP. Although variability did exist, relative cytokine increases in PRP compared to PPP were 151% for TGF-β1 and 415% for PDGF-AB. No correlation was noted between growth factor levels and platelet counts. Conclusion: These initial results demonstrate increases in both platelet counts and cytokine levels. Of concern, however, was the significant variation in these levels among PRP samples obtained from healthy volunteers using a commercially available device. References Marx RE, Carlson ER, Eichstaedt RM, et al: Platelet rich plasma: Growth factor enhancement for bone grafts. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 85:638, 1998 Weibrich G, Kleis WK, Hafner G: Growth factor levels in the platelet rich plasma produced by 2 different methods: Curasan-type PRP kit versus PCCS PRP system. Int J Oral Maxillofac Implants 17:184, 2002