title: Tenocytes of chronic rotator cuff tendon tears can be stimulated by platelet-released growth factors.
abstract: BACKGROUND
  Bone-to-tendon healing after rotator cuff repairs is mainly impaired by poor tissue quality. The tenocytes of chronic rotator cuff tendon tears are not able to synthesize normal fibrocartilaginous extracellular matrix (ECM). We hypothesized that in the presence of platelet-released growth factors (PRGF), tenocytes from chronically retracted rotator cuff tendons proliferate and synthesize the appropriate ECM proteins.
  
  
  METHODS
  Tenocytes from 8 patients with chronic rotator cuff tears were cultured for 4 weeks in 2 different media: standard medium (Iscove's Modified Dulbecco's Media + 10% fetal calf serum + 1% nonessential amino acids + 0.5 μg/mL ascorbic acid) and media with an additional 10% PRGF. Cell proliferation was assessed at 7, 14, 21, and 28 days. Messenger (m)RNA levels of collagens I, II, and X, decorin, biglycan, and aggrecan were analyzed using real time reverse-transcription polymerase chain reaction. Immunocytochemistry was also performed.
  
  
  RESULTS
  The proliferation rate of tenocytes was significantly higher at all time points when cultured with PRGF. At 21 days, the mRNA levels for collagens I, II, and X, decorin, aggrecan, and biglycan were significantly higher in the PRGF group. The mRNA data were confirmed at protein level by immunocytochemistry.
  
  
  CONCLUSIONS
  PRGFs enhance tenocyte proliferation in vitro and promote synthesis of ECM to levels similar to those found with insertion of the normal human rotator cuffs.
  
  
  CONCLUSIONS
  Biologic augmentation of repaired rotator cuffs with PRGF may enhance the properties of the repair tissue. However, further studies are needed to determine if application of PRGF remains safe and effective in long-term clinical studies.
  
  
  METHODS
  Basic Science Study, Cell Biology.
authors.affiliation: Orthopedic Sports Medicine, Department of Orthopedic Surgery and Traumatology, University of Bern, Inselspital, CH- 3010 Bern, Switzerland.
authors.forename: Sven
authors.initials: S
authors.lastname: Hoppe
authors.forename: Mauro
authors.initials: M
authors.lastname: Alini
authors.forename: Lorin M
authors.initials: LM
authors.lastname: Benneker
authors.forename: Stefan
authors.initials: S
authors.lastname: Milz
authors.forename: Pascal
authors.initials: P
authors.lastname: Boileau
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Zumstein
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002908:Chronic Disease; D003094:Collagen / Q000096:biosynthesis; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011509:Proteoglycans / Q000096:biosynthesis; D017006:Rotator Cuff / Q000601:surgery; D000070636:Rotator Cuff Injuries; D013708:Tendon Injuries / Q000473:pathology* / Q000601:surgery; D013710:Tendons / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology* / Q000601:surgery; D014945:Wound Healing / Q000187:drug effects
chemical_list: D016326:Extracellular Matrix Proteins; D010982:Platelet-Derived Growth Factor; D011509:Proteoglycans; D003094:Collagen