title: Polydioxanone biodegradable stent placement in a canine urethral model: analysis of inflammatory reaction and biodegradation.
abstract: OBJECTIVE
  To investigate the inflammatory reaction and perform quantitative analysis of biodegradation after placement of a polydioxanone (PDO) biodegradable stent in a canine urethral model.
  
  
  METHODS
  PDO biodegradable stents were placed in the proximal and distal urethra of nine male mongrel dogs. The dogs were euthanized 4 weeks (group A; n = 3), 8 weeks (group B; n = 3), or 12 weeks (group C; n = 3) after stent placement. The luminal diameter of the stent-implanted urethra was assessed by follow-up retrograde urethrography, and histologic findings were obtained after the dogs were killed. Stents were removed after euthanasia, and their surface morphology and molecular weight were evaluated. Hematologic examination was performed to evaluate inflammatory reaction.
  
  
  RESULTS
  Stent placement was technically successful in all dogs. The average luminal diameter gradually decreased. The average number of epithelial layers (2.93 vs 4.42; P < .001), the average thickness of papillary projection (0.80 mm vs 1.28 mm; P < .001), and the average thickness of submucosal fibrosis (0.34 mm vs 0.49 mm ; P < .001) were significantly increased in group B versus group A. There were no significant differences between group B and group C. The average inflammatory cell infiltration did not differ significantly in the three groups. Molecular weight losses were 54% in group A and 84% in group B. In group C, PDO stents were completely decomposed.
  
  
  CONCLUSIONS
  An experimental study in a canine urethral model has demonstrated acceptable inflammatory reaction with gradually increasing granulation tissue but no luminal obstruction within 12 weeks.
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Jung-Hoon
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea. Electronic address: hysong@amc.seoul.kr.
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Song
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Shin
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Jin Hyoung
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Jun
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Young Chul
authors.initials: YC
authors.lastname: Cho
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Soo Hwan
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Poongnap 2-dong, Songpa-gu, Seoul 138-736, Republic of Korea.
authors.forename: Jihong
authors.initials: J
authors.lastname: Park
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D004285:Dogs; D005355:Fibrosis; D005549:Foreign-Body Reaction / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D006097:Granulation Tissue; D007249:Inflammation / Q000000981:diagnostic imaging / Q000209:etiology* / Q000473:pathology; D008297:Male; D023421:Models, Animal; D008970:Molecular Weight; D016687:Polydioxanone / Q000737:chemistry*; D011474:Prosthesis Design; D011859:Radiography; D015607:Stents / Q000009:adverse effects*; D013499:Surface Properties; D013997:Time Factors; D014521:Urethra / Q000000981:diagnostic imaging / Q000473:pathology
chemical_list: D016687:Polydioxanone