Endoscopic submucosal dissection for pig esophagus by using photocrosslinkable chitosan hydrogel as submucosal fluid cushion.

BACKGROUND: Hypertonic saline solution (HS) as a submucosal fluid cushion (SFC) for endoscopic submucosal dissection (ESD) has several disadvantages, including a short effect duration and increased risk of bleeding and perforation. Photocrosslinkable chitosan hydrogel in DMEM/F12 medium (PCH) can be converted into an insoluble hydrogel by UV irradiation for 30 seconds. OBJECTIVE: To evaluate the feasibility, usefulness, and safety of PCH as an SFC for ESD of esophagi, compared with HS and sodium hyaluronate (SH). DESIGN: Survival animal study. SETTINGS: Research laboratory study of 24 pig models in vivo. INTERVENTIONS: Twenty-four pigs were used in the 2 steps: First, ESD of the esophagus was performed with PCH, SH, or HS (each n = 6) as an SFC, and the effects of these agents on wound healing were examined endoscopically and histologically. Second, in vivo degradation of PCH (n = 3) and HS (n = 3) was examined in independent pig esophagi. MAIN OUTCOME MEASUREMENTS: Outcome measurements included feasibility and safety of PCH-assisted ESD of esophagus, gross and histologic evidence of the treated esophagus, biodegradation of injected PCH, and clinical tolerance by the animals. RESULT: PCH injection led to a longer-lasting elevation with clearer margins compared with SH and HS, thus enabling precise ESD along the margins of the elevated mucosa without complications such as bleeding and perforation. The aspects of wound repair after PCH-assisted ESD were similar to those of SH- and HS-assisted ESDs. Biodegradation of PCH was confirmed to be almost completed within 8 weeks on the basis of endoscopic and histologic observations. LIMITATIONS: In vivo animal model study. CONCLUSION: PCH permits more reliable ESD of the esophagus without complications than do SH and HS. Furthermore, the applied PCH appeared to be completely biodegraded within 8 weeks. Thus, PCH is a promising agent as an SFC in ESD of the esophagus.

Coatings of low-density lipoprotein and synthetic glycoconjugates as substrata for hepatocytes.

Asialoglycoprotein (ASGP) receptors expressed on rat hepatocytes interact with glycoproteins containing galactose or N-acetylgalactosamine residues at the nonreducing termini of oligosaccharide chains to mediate endocytosis, and cholesterol transport protein with apolipoprotein B (LDL, low-density lipoprotein) in plasma interacts with LDL receptors and heparinoids in the extracellular matrix. We developed novel techniques to prepare galactose- and LDL-immobilized culture plates, using galactose-tagged polystyrene (galactose-carrying polystyrene [GalCPS]: N-p-vinylbenzyl-O-beta-D-galactopyranosyl-[1-->4]-D-gluconamide) and poly(2-acrylamide-2-methyl-1-propanesulfonate) (PAPS), respectively. Hepatocytes adhered well to plates coated with either GalCPS or LDL, and therefore the GalCPS- and LDL-coated plates were examined as specific substrata for culturing hepatocytes. These cultures promoted the formation of three-dimensional, multicellular aggregates with regulation of excess proliferation of non-parenchymal cells. Furthermore, the LDL coating resulted in higher albumin synthesis and an identical level of lactate dehydrogenase (LDH) compared with cells cultured on collagen- and GalCPS-coated plates. Thus, the two culture systems described here, and especially the LDL-coated plates, have potential for the development of a hybrid artificial liver.