title: Platelet-Rich Plasma Inhibits Mechanically Induced Injury in Chondrocytes.
abstract: OBJECTIVE
  To investigate the effect of platelet-rich plasma (PRP) on mechanically injured chondrocytes.
  
  
  METHODS
  PRP from bovine whole blood was activated to prepare platelet-rich plasma releasate (PRPr). Bovine articular chondrocytes were subjected to 16%, 0.5-Hz biaxial cyclic tensile strain (CTS) for 48 hours and cultured for another 24 hours without cell stretching as an in vitro model of mechanically injured chondrocytes. Culture medium in the 3 PRP- and CTS-treated groups was supplemented with 10% PRPr at the start of CTS, after 24 hours of CTS, and after 48 hours of CTS, respectively. Gene expression levels of type II collagen, aggrecan, matrix metalloproteinase (MMP)-3, MMP-13, inducible nitric oxide synthase, and cyclooxygenase 2 were quantitatively evaluated. Changes in the content of nitric oxide (NO), prostaglandin E2 (PGE2), MMP-3, and tissue inhibitor of metalloproteinase 1 in the culture medium were also measured.
  
  
  RESULTS
  PRPr increased type II collagen and aggrecan messenger RNA expression; diminished CTS-dependent up-regulation of MMP-3, inducible nitric oxide synthase, and cyclooxygenase 2 gene expression; and reduced CTS-induced overproduction of NO and PGE2 when PRPr was applied early at the start of CTS. The addition of PRPr after 24 hours of CTS only inhibited MMP-3 gene up-regulation and the increase of NO and PGE2 induced by CTS. These changes were not observed when PRPr was supplemented after 48 hours of CTS. PRPr mitigated the increased MMP-3 production and decreased tissue inhibitor of metalloproteinase 1 secretion resulting from CTS in a time-dependent manner.
  
  
  CONCLUSIONS
  PRP treatment ameliorated multiple CTS-mediated catabolic and inflammatory responses in chondrocytes. More beneficial effects were observed with early PRP application.
  
  
  CONCLUSIONS
  Intra-articular PRP injections at the beginning of strenuous exercises may be used to protect chondrocytes from mechanical injury, thus preventing joints from increased wear.
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A.; Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
authors.forename: Xuetao
authors.initials: X
authors.lastname: Xie
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A.
authors.forename: Veronica
authors.initials: V
authors.lastname: Ulici
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Alexander
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A.
authors.forename: Yangzi
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: Department of Orthopaedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
authors.forename: Changqing
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Center for Cellular and Molecular Engineering, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A.. Electronic address: rst13@pitt.edu.
authors.forename: Rocky S
authors.initials: RS
authors.lastname: Tuan
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D007718:Knee Injuries / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D053657:Platelet-Rich Plasma; D013314:Stress, Mechanical
chemical_list: D052247:Nitric Oxide Synthase Type II; D019278:Matrix Metalloproteinase 3