title: Platelet-rich plasma increases proliferation of tendon cells by modulating Stat3 and p27 to up-regulate expression of cyclins and cyclin-dependent kinases.
abstract: OBJECTIVE
  To investigate effects of platelet-rich plasma on tendon cell proliferation and the underlying molecular mechanisms.
  
  
  METHODS
  Platelet-rich plasma was prepared manually by two-step centrifugation. Proliferation was evaluated in cultured rat tendon cells by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. Cell cycle progression was assessed by flow cytometry. Messenger RNA expression of proliferating cell nuclear antigen (PCNA), cyclin E1, A2 and B1, and cyclin-dependent kinases (Cdks) 1 and 2 was assessed by real-time polymerase chain reaction. Protein expression of the above cyclins and Cdks and of signal transducer and activator of transcription (Stat) 3 and p27 was evaluated by western blotting.
  
  
  RESULTS
  Platelet-rich plasma used in the present study had concentrations of platelets, TGF-β1 and PDGF over 3-fold higher than normal whole blood. Platelet-rich plasma enhanced tendon cell proliferation (P = 0.008) by promoting G1 /S phase transition in the cell cycle, and increased expression of PCNA, cyclin E1, A2 and B1, Cdks1 and 2, and phosphorylated Stat3, while inhibiting p27 expression.
  
  
  CONCLUSIONS
  Platelet-rich plasma contains high concentrations of TGF-β1 and PDGF that increase tendon cell proliferation by modulating Stat3/p27(Kip1), which enhances expression of cyclin-Cdk complexes that promote cell cycle progression. These results provide molecular evidence for positive effects of platelet-rich plasma on tendon cell proliferation, which can be useful in clinical applications of tendon injury.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Linkou, 333, Taiwan.|Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: T-Y
authors.initials: TY
authors.lastname: Yu
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: J-H S
authors.identifier: http://orcid.org/0000-0003-3432-0208
authors.initials: JH
authors.lastname: Pang
authors.affiliation: Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Linkou, 333, Taiwan.
authors.forename: K P-H
authors.initials: KP
authors.lastname: Wu
authors.affiliation: Graduate Institute of Clinical Medical Sciences, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: L-P
authors.initials: LP
authors.lastname: Lin
authors.affiliation: Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Linkou, 333, Taiwan.
authors.forename: W-C
authors.initials: WC
authors.lastname: Tseng
authors.affiliation: Department of Physical Medicine and Rehabilitation, Chang Gung Memorial Hospital, Linkou, 333, Taiwan.|College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan.
authors.forename: W-C
authors.initials: WC
authors.lastname: Tsai
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase; D049109:Cell Proliferation; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000235:genetics*; D016213:Cyclins / Q000235:genetics*; D010982:Platelet-Derived Growth Factor / Q000378:metabolism; D053657:Platelet-Rich Plasma / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D013710:Tendons / Q000166:cytology*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D015854:Up-Regulation
chemical_list: C493962:Cdkn1b protein, rat; D016213:Cyclins; D010982:Platelet-Derived Growth Factor; D012333:RNA, Messenger; D050796:STAT3 Transcription Factor; D016212:Transforming Growth Factor beta; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016203:CDC2 Protein Kinase; C548796:Cdk1 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases