title: Effects of preparation method, shear force, and exposure to collagen on release of growth factors from equine platelet-rich plasma.
abstract: OBJECTIVE
  To test the hypotheses that preparation method, exposure to shear force, and exposure to collagen affect the release of growth factors from equine platelet-rich plasma (PRP).
  
  
  METHODS
  PRP obtained from 6 horses.
  
  
  METHODS
  PRP was prepared via 2 preparation methods (tube and automated) and subjected to 6 treatment conditions (resting, detergent, exposure to shear via 21- and 25-gauge needles, and exposure to collagen [10 and 20 μg/mL]). Concentrations of platelet-derived growth factor, isoform BB (PDGF-BB); transforming growth factor β, isoform 1 (TGFβ₁); and insulin-like growth factor, isoform 1 (IGF-1) were quantified by use of ELISAs. Statistical analysis was conducted via repeated-measures ANOVA.
  
  
  RESULTS
  Platelet numbers were significantly higher in tube-prepared PRP than in automated-prepared PRP Growth factor concentrations did not differ significantly between preparation methods. Mean PDGF-BB concentration ranged from 134 to 7,157 pg/mL, mean TGFβ₁ concentration ranged from 1,153 to 22,677 pg/mL, and mean IGF-1 concentration ranged from 150 to 280 ng/mL. Shear force did not affect growth factor concentrations. Dose-dependent increases in PDGF-BB and TGFβ₁ were detected in response to collagen, but equalled only 10% of the estimated total platelet content. Concentrations of IGF-1 were not significantly different among treatments and negative or positive control treatments. Serum concentrations of PDGF-BB and TGFβ₁ exceeded concentrations in PRP for most treatment conditions.
  
  
  CONCLUSIONS
  Release of growth factors from equine PRP was negligible as a result of the injection process alone. Investigation of platelet-activation protocols is warranted to potentially enhance PRP treatment efficacy in horses.
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. jamietextor@gmail.com
authors.forename: Jamie A
authors.initials: JA
authors.lastname: Textor
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Norris
authors.forename: Fern
authors.initials: F
authors.lastname: Tablin
mesh_terms: D000818:Animals; D003094:Collagen / Q000737:chemistry*; D006736:Horses / Q000097:blood*; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D053657:Platelet-Rich Plasma / Q000502:physiology*
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D003094:Collagen