title: Evaluation of submucosally injected polyethylene glycol-based hydrogel and bovine cross-linked collagen in the canine urethra using cystoscopy, magnetic resonance imaging and histopathology.
abstract: OBJECTIVE
  To (1) investigate the tissue response to a novel urethral bulking agent, polyethylene glycol carboxymethyl cellulose hydrogel (PEG-CMC) injected submucosally in the canine urethra and (2) compare PEG-CMC with bovine collagen (BC), the current standard for urethral bulking.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Purpose-bred female hound dogs (n = 8).
  
  
  METHODS
  Standardized submucosal urethral injections of BC and PEG-CMC were performed in 8 female dogs. Injection sites were evaluated by cystoscopy on days 0 (n = 8), 30 (n = 4), and 90 (n = 4), magnetic resonance imaging on days 0 (n = 8), 30 (n = 8), and 90 (n = 4) and by histopathology on days 30 (n = 4) and 90 (n = 4).
  
  
  RESULTS
  Both PEG-CMC and BC were detectable on MRI as hyperintense foci on T2-weighted images. Grossly, PEG-CMC formed more prominent blebs than BC. On follow-up cystoscopic examination, 6/8 PEG-CMC injection needle tracts were visible, and 3 of these sites had mucosal erosions. Histopathologic scores for foreign body reaction and inflammation were significantly higher for PEG-CMC compared with BC (P < 0.005). BC elicited a lymphoplasmacytic reaction whereas PEG-CMC incited a granulomatous response.
  
  
  CONCLUSIONS
  The overall physical characteristics and histologic response associated with PEG-CMC support its use as a urethral bulking agent; however, the current formulation needs to be adjusted for clinical use.
authors: Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors: Julia P
authors: JP
authors: Sumner
authors: Robert J
authors: RJ
authors: Hardie
authors: Jamie N
authors: JN
authors: Henningson
authors: Randi
authors: R
authors: Drees
authors: Mark D
authors: MD
authors: Markel
authors: Dale
authors: D
authors: Bjorling
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000008:administration & dosage; D002266:Carboxymethylcellulose Sodium / Q000008:administration & dosage* / Q000737:chemistry; D002417:Cattle; D003094:Collagen / Q000008:administration & dosage* / Q000737:chemistry; D003558:Cystoscopy / Q000662:veterinary; D004285:Dogs / Q000502:physiology*; D005260:Female; D020100:Hydrogels / Q000008:administration & dosage / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D011092:Polyethylene Glycols / Q000008:administration & dosage* / Q000737:chemistry; D019736:Prostheses and Implants; D014521:Urethra / Q000473:pathology / Q000502:physiology*
chemical_list: D001672:Biocompatible Materials; D020100:Hydrogels; D011092:Polyethylene Glycols; D003094:Collagen; D002266:Carboxymethylcellulose Sodium