title: Quantitative histologic evidence of amifostine-induced cytoprotection in an irradiated murine model of mandibular distraction osteogenesis.
abstract: BACKGROUND
  Head and neck cancer management requires adjuvant radiotherapy. The authors have previously demonstrated the damaging effect of a human equivalent dose of radiation on a murine mandibular model of distraction osteogenesis. Using quantitative histomorphometry, the authors' specific aim was to objectively measure amifostine radioprotection of the cellular integrity and tissue quality of an irradiated and distracted regenerate.
  
  
  METHODS
  Sprague-Dawley rats were assigned randomly into two groups: radiotherapy/distraction osteogenesis and amifostine/radiotherapy/distraction osteogenesis, which received amifostine before radiotherapy. Both groups received a fractionated human equivalent dose of radiation prior to left mandibular osteotomy with fixator placement. Distraction to 5.1 mm was followed by a 28-day consolidation period. Quantitative histomorphometry was performed on left hemimandibles for osteocytes, empty lacunae, bone volume-to-tissue volume ratio, and osteoid volume-to-tissue volume ratio.
  
  
  RESULTS
  Amifostine/radiotherapy/distraction osteogenesis exhibited bony bridging as opposed to radiotherapy/distraction osteogenesis fibrous unions. Quantitative histomorphometry analysis revealed statistically significant higher osteocyte count and bone volume-to-tissue volume ratio in amifostine-treated mandibles compared with irradiated mandibles. There was a corresponding decrease in empty lacunae and the ratio of osteoid volume-to-tissue volume between both groups.
  
  
  CONCLUSIONS
  The authors have successfully established the significant osseous cytoprotective and histoprotective capacity of amifostine for distraction osteogenesis in the face of radiotherapy. The amifostine-sparing effect on bone cellularity correlated with increased bony unions and elimination of fibrous union. The authors posit that the demonstration of similar efficacy of amifostine in the clinic may allow the successful implementation of distraction osteogenesis as a viable reconstructive option for head and neck cancer in the future.
authors.affiliation: Ann Arbor, Mich. From the University of Michigan Medical School, and the Department of Orthopedic Surgery, University of Michigan.
authors.forename: Catherine N
authors.initials: CN
authors.lastname: Tchanque-Fossuo
authors.forename: Alexis
authors.initials: A
authors.lastname: Donneys
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Razdolsky
authors.forename: Laura A
authors.initials: LA
authors.lastname: Monson
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Farberg
authors.forename: Sagar S
authors.initials: SS
authors.lastname: Deshpande
authors.forename: Deniz
authors.initials: D
authors.lastname: Sarhaddi
authors.forename: Behdod
authors.initials: B
authors.lastname: Poushanchi
authors.forename: Steven A
authors.initials: SA
authors.lastname: Goldstein
authors.forename: Steven R
authors.initials: SR
authors.lastname: Buchman
mesh_terms: D004999:Amifostine / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D004334:Drug Administration Schedule; D016267:External Fixators; D007091:Image Processing, Computer-Assisted; D008334:Mandible / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects / Q000601:surgery; D063168:Mandibular Osteotomy; D010011:Osteocytes / Q000187:drug effects / Q000473:pathology / Q000528:radiation effects; D019857:Osteogenesis, Distraction / Q000295:instrumentation / Q000379:methods*; D011833:Radiation Injuries, Experimental / Q000209:etiology / Q000517:prevention & control*; D011837:Radiation-Protective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D011837:Radiation-Protective Agents; D004999:Amifostine