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Background: Previous studies of bioactive molecules in platelet-rich plasma (PRP) have documented growth factor concentrations that promote tissue healing. However, the effects of leukocytes and inflammatory molecules in PRP have not been defined.

Hypothesis: The hypothesis for this study was that the concentration of growth factors and catabolic cytokines would be dependent on the cellular composition of PRP.

Study Design: Controlled laboratory study.

Methods: Platelet-rich plasma was made from 11 human volunteers using 2 commercial systems: Arthrex ACP (Autologous Conditioned Plasma) Double Syringe System (PRP-1), which concentrates platelets and minimizes leukocytes, and Biomet GPS III Mini Platelet Concentrate System (PRP-2), which concentrates both platelets and leukocytes. Transforming growth factor-β1 (TGF-β1), platelet-derived growth factor–AB (PDGF-AB), matrix metalloproteinase-9 (MMP-9), and interleukin-1β (IL-1β) were measured with enzyme-linked immunosorbent assay (ELISA).

Results: The PRP-1 system consisted of concentrated platelets (1.99x) and diminished leukocytes (0.13x) compared with blood, while PRP-2 contained concentrated platelets (4.69x) and leukocytes (4.26x) compared with blood. Growth factors were significantly increased in PRP-2 compared with PRP-1 (TGF-β1: PRP-2 = 89 ng/mL, PRP-1 = 20 ng/mL, P < .05; PDGF-AB: PRP-2 = 22 ng/mL, PRP-1 = 6.4 ng/mL, P < .05). The PRP-1 system did not have a higher concentration of PDGF-AB compared with whole blood. Catabolic cytokines were significantly increased in PRP-2 compared with PRP-1 (MMP-9: PRP-2 = 222 ng/mL, PRP-1 = 40 ng/mL, P < .05; IL-1β: PRP-2 = 3.67 pg/mL, PRP-1 = 0.31 pg/mL, P < .05). Significant, positive correlations were found between TGF-β1 and platelets (r ² = .75, P < .001), PDGF-AB and platelets (r ² = .60, P < .001), MMP-9 and neutrophils (r ² = .37, P < .001), IL-1β and neutrophils (r ² = .73, P < .001), and IL-1β and monocytes (r ² = .75, P < .001).

Conclusion: Growth factor and catabolic cytokine concentrations were influenced by the cellular composition of PRP. Platelets increased anabolic signaling and, in contrast, leukocytes increased catabolic signaling molecules. Platelet-rich plasma products should be analyzed for content of platelets and leukocytes as both can influence the biologic effects of PRP.

Clinical Relevance: Depending on the clinical application, preparations of PRP should be considered based on their ability to concentrate platelets and leukocytes with sensitivity to pathologic conditions that will benefit most from increased platelet or reduced leukocyte concentration.

Background: Clinical studies claim that platelet-rich plasma (PRP) shortens recovery times because of its high concentration of growth factors that may enhance the tissue repair process. Most of these studies obtained PRP using different separation systems, and few analyzed the content of the PRP used as treatment.

Purpose: This study characterized the composition of single-donor PRP produced by 3 commercially available PRP separation systems.

Study Design: Controlled laboratory study.

Methods: Five healthy humans donated 100 mL of blood, which was processed to produce PRP using 3 PRP concentration systems (MTF Cascade, Arteriocyte Magellan, Biomet GPS III). Platelet, white blood cell (WBC), red blood cell, and fibrinogen concentrations were analyzed by automated systems in a clinical laboratory, whereas ELISA determined the concentrations of platelet-derived growth factor β and ββ (PDGF-β, PDGF-ββ), transforming growth factor β1 (TGF-β1), and vascular endothelial growth factor (VEGF).

Results: There was no significant difference in mean PRP platelet, red blood cell, active TGF-β1, or fibrinogen concentrations among PRP separation systems. There was a significant difference in platelet capture efficiency. The highest platelet capture efficiency was obtained with Cascade, which was comparable with Magellan but significantly higher than GPS III. There was a significant difference among all systems in the concentrations of WBC, PDGF-β, PDGF-ββ, and VEGF. The Cascade system concentrated leukocyte-poor PRP, compared with leukocyte-rich PRP from the GPS III and Magellan systems.

Conclusion: The GPS III and Magellan concentrate leukocyte-rich PRP, which results in increased concentrations of WBCs, PDGF-β, PDGF-ββ, and VEGF as compared with the leukocyte-poor PRP from Cascade. Overall, there was no significant difference among systems in the platelet concentration, red blood cell, active TGF-β1, or fibrinogen levels.

Clinical Relevance: Products from commercially available PRP separation systems produce differing concentrations of growth factors and WBCs. Further research is necessary to determine the clinical relevance of these findings.