title: Submucosal injection, for endoscopic mucosal resection, of photocrosslinkable chitosan hydrogel in DMEM/F12 medium.
abstract: OBJECTIVE
  We studied the ability of a photocrosslinkable chitosan in DMEM/F12 medium to maintain submucosal thickness and to reduce bleeding after mucosal resection. We also investigated the behavior of chitosan hydrogels with regard to wound healing.
  
  
  METHODS
  The gastric submucosal layer of heparinized rats was injected with the photocrosslinkable chitosan in medium (which was then irradiated with ultraviolet light to form a hydrogel), or with sodium hyaluronate, or hypertonic saline, and three investigations were done, using three different sets of rats. The first and second were measurement of the thickness of the layer, and of the amount of bleeding induced by mucosal resection, respectively. Thirdly, the effects of the chitosan hydrogel on wound healing were examined histologically.
  
  
  RESULTS
  Gastric submucosal layers of chitosan hydrogel-treated animals remained significantly thicker than those of other groups for at least 6 h after injection. The total amount of bleeding 20 min after mechanical mucosal resection was 170.0 +/- 20.0 mg, 678.3 +/- 226.3 mg, and 1020.0 +/- 104.1 mg in the chitosan hydrogel, sodium hyaluronate, and hypertonic saline groups, respectively. Histological study revealed that the focus of bleeding was surrounded by chitosan hydrogel and that almost all the hydrogel was biodegraded within 4 weeks. Furthermore, a discernible, but not statistically significant effect of the chitosan hydrogel on wound healing was observed.
  
  
  CONCLUSIONS
  The chitosan hydrogel produced mucosal elevation after submucosal injection with ultraviolet irradiation, and it significantly reduced bleeding after mucosal resection. Our newly developed chitosan hydrogel in medium might be a promising submucosal agent for endoscopic mucosal resection.
authors.affiliation: Dept. of Surgery II, National Defense Medical College, Tokorozawa, Saitama, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ishizuka
authors.forename: T
authors.initials: T
authors.lastname: Hayashi
authors.forename: M
authors.initials: M
authors.lastname: Ishihara
authors.forename: Y
authors.initials: Y
authors.lastname: Yoshizumi
authors.forename: S
authors.initials: S
authors.lastname: Aiko
authors.forename: S
authors.initials: S
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Yura
authors.forename: Y
authors.initials: Y
authors.lastname: Kanatani
authors.forename: Y
authors.initials: Y
authors.lastname: Nogami
authors.forename: T
authors.initials: T
authors.lastname: Maehara
mesh_terms: D000818:Animals; D048271:Chitosan / Q000008:administration & dosage*; D016099:Endoscopy, Gastrointestinal / Q000009:adverse effects / Q000379:methods*; D005753:Gastric Mucosa / Q000473:pathology*; D006471:Gastrointestinal Hemorrhage / Q000209:etiology; D007267:Injections / Q000009:adverse effects / Q000379:methods*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D048271:Chitosan