title: Strain induced esophageal growth in a novel rodent model.
abstract: OBJECTIVE
  Longitudinal esophageal strain has been shown to increase esophageal length but the contribution of tissue hyperplasia to this growth is unknown. We used a novel model of esophageal stretch to determine the cellular response to the strain stimulus.
  
  
  METHODS
  Male Sprague-Dawley rats underwent transection of the distal esophagus. The distal stump was ligated and stretched over a silicone tube. The proximal esophageal stump was anastomosed to the stomach to restore continuity. After two, four, or seven days, the silicone tube was removed and the esophageal segment was measured and compared to its initial length. Sham animals had only a thin piece of silicone tubing placed. Standardized histologic sections were evaluated for wall thickness. Immunofluorescence with DAPI, Ki-67, and Myogenin antibodies was used to assess nuclear density, proliferation indices, and myoblast differentiation indices.
  
  
  RESULTS
  Experimental animals demonstrated a significant increase in esophageal length compared to sham controls at four and seven days with no difference at two days. There was significant lengthening between four and seven days among the experimental animals. There was no change in wall thickness between experimental and sham animals at any time point. Nuclear density was increased at all time points, although this only reached significance at day four. Proliferation indices were significantly increased relative to sham controls at all time points. Esophageal strain induced significantly increased myoblast differentiation.
  
  
  CONCLUSIONS
  In this novel rat model of esophageal strain, lengthening is associated with stable esophageal wall thickness, increased nuclear density, increased cellular proliferation, and increased myogenin expression. These data suggest that true tissue hyperplasia may contribute to the increased length seen after esophageal strain.
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: nora.fullington@umassmemorial.org.
authors.forename: Nora M
authors.initials: NM
authors.lastname: Fullington
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: kristina.potanos@baystatehealth.org.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Potanos
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: rcauley@partners.org.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Cauley
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: patty.purcellm@gmail.com.
authors.forename: Patricia
authors.initials: P
authors.lastname: Purcell
authors.affiliation: Department of Plastic Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: david.zurakowski@childrens.harvard.edu.
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: steven.fishman@childrens.harvard.edu.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Fishman
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: khashayar.vakili@childrens.harvard.edu.
authors.forename: Khashayar
authors.initials: K
authors.lastname: Vakili
authors.affiliation: Department of Surgery, Boston Children's Hospital, Boston, MA, 02115, USA. Electronic address: heung.kim@childrens.harvard.edu.
authors.forename: Heung Bae
authors.initials: HB
authors.lastname: Kim
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D004947:Esophagus / Q000254:growth & development* / Q000473:pathology; D006965:Hyperplasia; D008297:Male; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley
keywords: Esophagus; Growth; Lengthening; Strain; Stretch; Tension