title: Extraluminal distraction enterogenesis using shape-memory polymer.
abstract: OBJECTIVE
  Although a few techniques for lengthening intestine by mechanical stretch have been described, they are relatively complex, and the majority involve placement of an intraluminal device. Ideally, techniques applicable to humans would be easy to perform and extraluminal to avoid the potential for mucosal injury. This study of distraction enterogenesis used an extraluminal, radially self-expanding shape-memory polymer cylinder and a simple operative approach to both elongate intestine and grow new tissue.
  
  
  METHODS
  Young Sprague Dawley rats (250-350 g) underwent Roux-en-Y isolation of a small intestinal limb and were divided in three groups: no further manipulation (Control 1, C1); placement of a nonexpanding device (Control 2, C2); or placement of a radially expanding device by the limb (Experimental, Exp). For C2 and Exp animals, the blind end of the limb was wrapped around the radially expanding cylindrical device with the limb-end sutured back to the limb-side. Bowel length was measured at operation and at necropsy (14 days) both in-situ and ex-vivo under standard tension (6g weight). Change in length is shown as mean ± standard deviation. A blinded gastrointestinal pathologist reviewed histology and recorded multiple measures of intestinal adaptation. The DNA to protein ratio was quantified as a surrogate for cellular proliferation. Changes in length, histologic measures, and DNA:protein were compared using analysis of variance, with significance set at P<0.05.
  
  
  RESULTS
  The length of the Roux limb in situ increased significantly in Exp animals (n=8, 29.0 ± 5.8mm) compared with C1 animals (n=5, -11.2 ± 9.0mm, P<0.01). The length of the Roux limb ex vivo under standard tension increased in the Exp group (25.8 ± 4.2mm) compared with the C2 group (n=6, -4.3 ± 6.0, P<0.01). There were no differences in histologic measures of bowel adaptation between the groups, namely villous height and width, crypt depth, crypt density, and crypt fission rate (all P ≥ 0.08). Muscularis mucosal thickness was also not different (P=0.25). There was no difference in DNA:protein between groups (P=0.47).
  
  
  CONCLUSIONS
  An extraluminally placed, radially expanding shape-memory polymer cylinder successfully lengthened intestine, without damaging mucosa. Lack of difference in muscularis thickness and a constant DNA:protein ratio suggests that this process may be related to actual growth rather than mere stretch. This study demonstrated a simple approach that warrants further study aiming at potential clinical applicability.
authors: Center for Advanced Intestinal Rehabilitation (CAIR), Boston Children's Hospital and Harvard Medical School, Boston, MA; Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Jeremy G
authors: JG
authors: Fisher
authors: Center for Advanced Intestinal Rehabilitation (CAIR), Boston Children's Hospital and Harvard Medical School, Boston, MA; Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Eric A
authors: EA
authors: Sparks
authors: Center for Advanced Intestinal Rehabilitation (CAIR), Boston Children's Hospital and Harvard Medical School, Boston, MA; Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Faraz A
authors: FA
authors: Khan
authors: Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Beatrice
authors: B
authors: Dionigi
authors: Department of Pathology, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Hao
authors: H
authors: Wu
authors: Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Joseph
authors: J
authors: Brazzo
authors: Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Dario
authors: D
authors: Fauza
authors: Center for Advanced Intestinal Rehabilitation (CAIR), Boston Children's Hospital and Harvard Medical School, Boston, MA; Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA.
authors: Biren
authors: B
authors: Modi
authors: MedShape, Inc., Atlanta, GA.
authors: David L
authors: DL
authors: Safranski
authors: Center for Advanced Intestinal Rehabilitation (CAIR), Boston Children's Hospital and Harvard Medical School, Boston, MA; Department of Surgery, Boston Children's Hospital and Harvard Medical School, Boston, MA. Electronic address: tom.jaksic@childrens.harvard.edu.
authors: Tom
authors: T
authors: Jaksic
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D049109:Cell Proliferation; D007421:Intestine, Small / Q000166:cytology / Q000254:growth & development*; D023421:Models, Animal; D009130:Muscle, Smooth / Q000254:growth & development; D011108:Polymers; D017207:Rats, Sprague-Dawley; D012778:Short Bowel Syndrome / Q000601:surgery; D015626:Tissue Expansion / Q000295:instrumentation* / Q000379:methods*
chemical_list: D011108:Polymers
keywords: Biological markers; Citrulline; Intestinal adaptation; Intestinal failure; Short bowel syndrome