title: Expansion thoracoplasty affects lung growth and morphology in a rabbit model: a pilot study.
abstract: BACKGROUND
  Thoracic insufficiency syndrome represents a novel form of postnatal restrictive respiratory disease occurring in children with early-onset scoliosis and chest wall anomalies. Expansion thoracoplasty improves lung volumes in children with thoracic insufficiency syndrome; however, how it affects lung development is unknown.
  
  
  OBJECTIVE
  Using a rabbit model of thoracic insufficiency syndrome, we evaluated the effect of expansion thoracoplasty on the response of biologic mechanisms in the alveolar microstructure.
  
  
  METHODS
  Using archived material from a previous experiment, 10 4-week-old New Zealand rabbits were divided into three groups: normal (n = 3), disease (n = 3), and treated (n = 4). Left ribs four to eight were tethered in seven rabbits at age 5 weeks to induce hypoplasia of the left hemithorax (disease). At age 10 weeks, four of these rabbits were treated by expansion thoracoplasty (treated). At age 24 weeks, lungs were excised and processed. Alveolar density and parenchymal airspace were measured on histologic sections. Immunohistochemistry was performed for vascular endothelial growth factor receptor 2 (angiogenesis), KI-67 (cell proliferation), and RAM-11 (macrophages).
  
  
  RESULTS
  Alveolar walls were poorly perfused and airspace fraction was larger (emphysematous) in disease rabbits than normal or treated rabbits. Immunohistochemistry provided inconclusive evidence to support the concept that pulmonary hypoplasia is induced by thoracic insufficiency syndrome and controlled by expansion thoracoplasty.
  
  
  CONCLUSIONS
  Treatment of thoracic insufficiency syndrome by expansion thoracoplasty may prevent emphysematous changes in the alveolar microstructure, thereby enhancing gas exchange.
authors.affiliation: Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: J Casey
authors.initials: JC
authors.lastname: Olson
authors.forename: Kyle C
authors.initials: KC
authors.lastname: Kurek
authors.forename: Hemal P
authors.initials: HP
authors.lastname: Mehta
authors.forename: Matt L
authors.initials: ML
authors.lastname: Warman
authors.forename: Brian D
authors.initials: BD
authors.lastname: Snyder
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D019394:Ki-67 Antigen; D008168:Lung / Q000098:blood supply / Q000254:growth & development / Q000473:pathology / Q000601:surgery*; D008264:Macrophages / Q000473:pathology; D018919:Neovascularization, Physiologic; D009687:Nuclear Proteins / Q000378:metabolism; D010865:Pilot Projects; D011817:Rabbits; D012131:Respiratory Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D012272:Ribs / Q000000981:diagnostic imaging / Q000254:growth & development / Q000601:surgery; D013905:Thoracoplasty; D000074482:Thyroid Nuclear Factor 1; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014157:Transcription Factors / Q000378:metabolism; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D019394:Ki-67 Antigen; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors; D040301:Vascular Endothelial Growth Factor Receptor-2