title: Evidence that translocation of collagen fibril segments plays a role in early intrinsic tendon repair.
abstract: BACKGROUND
  Severed tendon repair advances with either a scar through extrinsic repair or regeneration through intrinsic repair. The authors examined whether intrinsic tendon repair reintroduces embryonic fibrillogenesis, whereby preformed collagen fibril segments are incorporated into growing collagen fibers at wound edges.
  
  
  METHODS
  Isolated tendons from 10-day-old chicken embryos were suspended in 1 mg/ml of the antibiotic gentamicin for 90 days, which released fibril segments that were fluorescently tagged with rhodamine. Tendons isolated from 14-day-old chicken embryos were wounded to half their diameter and then maintained as explants in stationary organ culture. Fluorescent-tagged fibril segments were introduced to wounded tendon explants in the presence of high concentrations of neomycin, an antibiotic; cycloheximide, a protein synthesis inhibitor; cytochalasin D, a disruptor of microfilaments; and colchicine, a disruptor of microtubules. At 24 hours, explants were viewed by means of fluorescent microscopy.
  
  
  RESULTS
  Untreated, wounded tendon explants showed the translocation of fluorescent-tagged fibril segments from the explant surface to accumulation at wound edges. In the presence of high concentrations of neomycin, cytochalasin D, or colchicine, fluorescent-tagged fibril segments failed to accumulate at wound edges and were retained on the explant surface. Inhibition of protein synthesis by cycloheximide did not alter the accumulation of fluorescent-tagged fibril segments at wound edges.
  
  
  CONCLUSIONS
  Inhibiting fluorescent-tagged fibril segment accumulation by antibiotics is consistent with their role in releasing fibril segments. Experimental findings show fibril segment translocation and accumulation at wound edges involves microfilaments and microtubules, but not protein synthesis. The experiments support the hypothesis that intrinsic tendon repair advances through the incorporation of fibril segments at wound edges.
authors.affiliation: Hershey, Pa. From the Division of Plastic Surgery, The Pennsylvania State University, College of Medicine.
authors.forename: J Stephen
authors.initials: JS
authors.lastname: Gunn
authors.forename: H Paul
authors.initials: HP
authors.lastname: Ehrlich
mesh_terms: D000818:Animals; D002642:Chick Embryo; D003094:Collagen / Q000502:physiology* / Q000648:ultrastructure; D013708:Tendon Injuries; D013710:Tendons / Q000196:embryology; D014945:Wound Healing
chemical_list: D003094:Collagen