title: A large animal model of the fetal tracheal stenosis/atresia spectrum.
abstract: BACKGROUND
  Treatment of congenital tracheal stenosis/atresia remains essentially unresolved. Previous models of this disease entity have been restricted to rodents and the chick. We sought to establish the principles of a large, surgical animal model of this spectrum of fetal anomalies.
  
  
  METHODS
  Fetal lambs (n = 8) underwent open surgery at 90-112 days gestation. Their cervical tracheas were encircled by a biocompatible polytetrafluoroethylene wrap, so as to extrinsically restrict their external diameter by 25%. Survivors (n = 7) were killed at different time points post-operatively before term. The manipulated tracheal segments were compared with their respective proximal portions (controls). Analyses included morphometry, histology and quantitative extracellular matrix measurements.
  
  
  RESULTS
  At necropsy, the typical gross appearance of tracheal stenosis/atresia was present in all manipulated tracheal segments. Histological findings included the virtual disappearance of the membranous portion of the trachea, along with infolding, fragmentation, and/or posterior fusion of cartilaginous rings, often with disappearance of the airway mucosa. There were significant decreases in diameter (P < 0.001) and total collagen levels (P = 0.005) on the manipulated trachea compared with the control portions. No significant differences were observed in overall elastin or glycosaminoglycan contents. A significant time-dependent increase in elastin was noted on the control, but not the experimental side.
  
  
  CONCLUSIONS
  In a surgical ovine model, controlled extrinsic compression of the fetal trachea leads to morphological and biochemical findings compatible with the congenital tracheal stenosis/atresia spectrum. This simple and easily reproducible prenatal model can be instrumental in the development of emerging therapies for these congenital anomalies.
authors.affiliation: Department of Surgery, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Christopher G B
authors.initials: CG
authors.lastname: Turner
authors.forename: Justin D
authors.initials: JD
authors.lastname: Klein
authors.forename: Azra
authors.initials: A
authors.lastname: Ahmed
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.forename: Dario O
authors.initials: DO
authors.lastname: Fauza
mesh_terms: D000818:Animals; D001672:Biocompatible Materials; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D004549:Elastin / Q000378:metabolism; D005109:Extracellular Matrix / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005333:Fetus / Q000601:surgery; D005465:Fluorocarbon Polymers; D038081:Organogenesis; D011247:Pregnancy; D012756:Sheep; D014132:Trachea / Q000002:abnormalities* / Q000473:pathology*; D014135:Tracheal Stenosis / Q000473:pathology*
chemical_list: D001672:Biocompatible Materials; D005465:Fluorocarbon Polymers; C010946:polytetrafluoroethane; D003094:Collagen; D004549:Elastin