title: Leukocyte concentration and composition in platelet-rich plasma (PRP) influences the growth factor and protease concentrations.
abstract: BACKGROUND
  Platelet-rich plasma (PRP) therapy has become an increasingly popular treatment for orthopaedics and sports-related injuries, and various clinically available PRP preparation methods exist. However, the differences in PRP quality among numerous preparation methods remain unclear. Specifically, the benefit of including leukocytes in the PRP product remains controversial, and few studies have been conducted to evaluate the effects of the interaction between platelets and leukocytes on the growth factor concentrations. The aim of the present study was to compare the biological characteristics of PRPs focusing on the leukocyte concentration and composition.
  
  
  METHODS
  Leucocyte rich (LR)-PRP, leucocyte poor (LP)-PRP, and pure-PRP were prepared from the peripheral blood of 6 healthy male volunteers (mean age: 31.3 years). The concentrations of platelets, leukocytes, erythrocytes, growth factors (transforming growth factor-beta 1: TGF-β1; fibroblast growth factor-basic: FGF-b; platelet-derived growth factor-BB: PDGF-BB; vascular endothelial growth factor: VEGF) and matrix metalloproteinase-9 (MMP-9) from each of the PRP samples were measured. Considering the interaction between platelets and leukocytes, correlations between platelets/leukocytes and growth factors/MMP-9 were analyzed using partial correlation coefficients.
  
  
  RESULTS
  The platelet concentration did not differ among the three PRP preparation methods. Conversely, the leukocyte concentration was dramatically different: 14.9 ± 4.5 (10(3)/μl) in LR-PRP, 2.4 ± 1.3 (10(3)/μl) in LP-PRP, 0.2 ± 0.2 (10(3)/μl) in pure-PRP. The platelet concentration positively correlated with all growth factors. On the other hand, the leukocyte concentration positively correlated with PDGF-BB and the VEGF concentration, while it negatively correlated with FGF-b. Regarding catabolic factors, the MMP-9 concentration strongly correlated with the leukocyte concentration, while there was no correlation between the platelet and MMP-9 concentrations.
  
  
  CONCLUSIONS
  These findings demonstrate that leukocytes strongly influence the quality of PRPs. Therefore, modifying the PRP preparation method according to the pathology is essential to achieve better clinical results with PRP therapy.
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Yohei
authors: Y
authors: Kobayashi
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan. Electronic address: ysaita@juntendo.ac.jp.
authors: Yoshitomo
authors: Y
authors: Saita
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Hirofumi
authors: H
authors: Nishio
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Hiroshi
authors: H
authors: Ikeda
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Yuji
authors: Y
authors: Takazawa
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Masashi
authors: M
authors: Nagao
authors: Department of Hematology, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Tomoiku
authors: T
authors: Takaku
authors: Department of Hematology, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Norio
authors: N
authors: Komatsu
authors: Department of Orthopaedics, Juntendo University, Faculty of Medicine, Tokyo, Japan.
authors: Kazuo
authors: K
authors: Kaneko
mesh_terms: D000328:Adult; D015331:Cohort Studies; D004906:Erythrocyte Count; D005346:Fibroblast Growth Factors / Q000097:blood; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D010447:Peptide Hydrolases / Q000378:metabolism*; D010976:Platelet Count; D010982:Platelet-Derived Growth Factor / Q000032:analysis*; D053657:Platelet-Rich Plasma / Q000737:chemistry / Q000166:cytology*; D011786:Quality Control; D055815:Young Adult
chemical_list: D010982:Platelet-Derived Growth Factor; D005346:Fibroblast Growth Factors; D010447:Peptide Hydrolases