title: In vitro immunological and biological evaluations of the angiogenic potential of platelet-rich fibrin preparations: a standardized comparison with PRP preparations.
abstract: BACKGROUND
  Platelet-rich fibrin (PRF), a platelet-rich plasma (PRP) derivative mainly composed of fibrin networks, has been increasingly demonstrated to be effective in wound healing in clinical and pre-clinical animal studies. However, there has still been a concern that major growth factors may significantly be loss from PRF during its preparation through the slow clotting process. To address this concern, we compared the angiogenic potential of PRF and PRP by standardization of procedures based on volume ratios.
  
  
  METHODS
  PRP, PRF, and platelet-poor plasma (PPP) were prepared from the peripheral blood of healthy donors. PRF preparations were squeezed or homogenized to produce exudate (PRFexu) or extract (PRFext), respectively. Concentrations of the angiogenic factors and their bioactivities were determined using ELISA kits, a scratch assay using endothelial cells and a chicken chorioallantoic membrane (CAM) assay.
  
  
  RESULTS
  In PRP and PRF preparations, both VEGF and PDGF-BB were significantly more concentrated than PPP. In the scratch assay, PRFexu and PRFext were the most effective for wound closure. In the CAM assay, PRF membranes were the most effective for neovascularization.
  
  
  CONCLUSIONS
  It is suggested that PRF preparations efficiently preserve the angiogenic factors and function not only as a scaffolding material but as a reservoir of angiogenic factors in wound healing.
authors.affiliation: Division of Oral Bioengineering, Institute of Medicine and Dentistry, Niigata University, Niigata, Japan.|Division of Periodontology, Institute of Medicine and Dentistry, Niigata University, Niigata, Japan.
authors.forename: Mito
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Division of Oral Bioengineering, Institute of Medicine and Dentistry, Niigata University, Niigata, Japan. kawase@dent.niigata-u.ac.jp.|Advanced Research Center, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan. kawase@dent.niigata-u.ac.jp.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Kawase
authors.affiliation: Division of Periodontology, Institute of Medicine and Dentistry, Niigata University, Niigata, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Okuda
authors.affiliation: Division of Periodontology, Department of Developmental and Surgical Sciences, University of Minnesota School of Dentistry, Minneapolis, MN, USA.
authors.forename: Larry F
authors.initials: LF
authors.lastname: Wolff
authors.affiliation: Division of Periodontology, Institute of Medicine and Dentistry, Niigata University, Niigata, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Yoshie
keywords: Angiogenesis; Endothelial cells; Fibrin; Plasma; Platelets