Usefulness of photocrosslinkable chitosan for endoscopic cancer treatment in alimentary tract.

Endoscopic mucosal resection (EMR), an established treatment for superficial cancer in the stomach, colon, and esophagus, involves extracting the lesion with the aid of high-frequency current (as in snare polypectomy), following saline injection into the submucosal layer. Of interest in this study was the ability of photocrosslinkable chitosan, which is converted to a hydrogel (like a soft rubber) by 30-s ultraviolet irradiation, to expand the submucosal layer when used as an injection material. Photocrosslinkable-chitosan solution or normal saline (0.3 mL) was injected into the submucosal layer of the rat stomach, and the thickness of this layer was measured at various time points thereafter. In these two groups, the values obtained were 3.8 and 2.0 mm, respectively (means; n = 5 each group; p < 0.005), at 30 min after the injection. The cumulative blood loss measured at 20 min after mucosal incision was 113 mg (photocrosslinkable-chitosan solution), versus 1682 mg (saline) (means, n = 10 each group; p < 0.001). Histologic observation revealed that chitosan, which was retained within the submucosal layer, filled the ulcer base and completely surrounded the bleeding focus. Thus, the photocrosslinkable chitosan developed holds promise for use in EMR as a submucosal injection agent that avoids complications. (c) 2004 Wiley Periodicals, Inc.