title: Experimental study of poly-L-lactic acid biodegradable stents in normal canine bile ducts.
abstract: OBJECTIVE
  This study was designed to clarify the advantages of biodegradable stents in terms of mucosal reaction and biodegradation after placement. We designed a biodegradable stent and assessed stent degradation and changes in the normal bile ducts of dogs.
  
  
  METHODS
  The biodegradable stent is a balloon-expandable Z stent consisting of poly-L-lactic acid (PLLA) with a diameter of 6 mm and a length of 15 mm. We assessed four groups of three beagle dogs each at 1, 3, 6, and 9 months of follow-up. After evaluating stent migration by radiography and stent and bile duct patency by cholangiography, the dogs were sacrificed to remove the bile duct together with the stent. The bile duct lumen was examined macroscopically and histologically, and the stent degradation was examined macroscopically and by scanning electron microscopy (SEM).
  
  
  RESULTS
  Bile duct obstruction was absent and none of the stents migrated. Macroscopic evaluation showed moderate endothelial proliferation in the bile ducts at the implant sites at 3 and 6 months and a slight change at 9 months. Slight mononuclear cell infiltration was histologically identified at all time points and epithelial hyperplasia that was moderate at 3 months was reduced to slight at 6 and 9 months. Stent degradation was macroscopically evident in all animals at 9 months and was proven by SEM in two dogs at 6 months and in all of them at 9 months.
  
  
  CONCLUSIONS
  Our results suggest that PLLA bioabsorbable stents seems to be useful for implantation in the biliary system with further investigation.
authors.affiliation: Department of Radiology, Nara Medical University, Kashihara, Nara, Japan. yamakiyo@zg7.so-net.ne.jp
authors.forename: Kiyosei
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Yoshioka
authors.forename: Kinya
authors.initials: K
authors.lastname: Furuichi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakaguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Anai
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Tanaka
authors.forename: Kengo
authors.initials: K
authors.lastname: Morimoto
authors.forename: Hideo
authors.initials: H
authors.lastname: Uchida
authors.forename: Kimihiko
authors.initials: K
authors.lastname: Kichikawa
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001652:Bile Ducts; D001672:Biocompatible Materials; D002758:Cholangiography; D003287:Contrast Media / Q000008:administration & dosage; D003974:Diatrizoate Meglumine / Q000008:administration & dosage; D004285:Dogs; D019344:Lactic Acid; D008297:Male; D023421:Models, Animal; D011091:Polyesters; D011108:Polymers; D011474:Prosthesis Design; D015607:Stents
chemical_list: D001672:Biocompatible Materials; D003287:Contrast Media; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; D003974:Diatrizoate Meglumine; C033616:poly(lactide)