title: Improved survival and ammonia metabolism by intraperitoneal transplantation of microencapsulated hepatocytes in totally hepatectomized rats.
abstract: BACKGROUND
  We evaluated the effects of intraperitoneal transplantation of microencapsulated hepatocytes in a 3-stage total hepatectomy rat model.
  
  
  METHODS
  A new model of total hepatectomy was created as follows. First, the infrahepatic inferior vena cava was ligated just above the right renal vein. Seven days later, the portal vein was ligated and a portacaval shunt was established using a Teflon catheter over a venipuncture needle. Another 7 days later, total hepatectomy was completed by ligating and dividing the suprahepatic inferior vena cava, the hepatic artery, and the bile duct. Next, 4 x 10(7) hepatocytes (4% of the normal liver hepatocyte mass) isolated from male Wistar rats were microencapsulated within a collagen matrix enveloped by a 3-layer membrane of sodium alginate-poly-L-lysine-sodium alginate copolymer. Capsules containing hepatocytes (diameter, 500-800 microm) and empty capsules (control) were transplanted intraperitoneally 4 days before the total hepatectomy. Survival time and selected blood chemistry concentrations after the total hepatectomy were measured. The capsules were also examined histologically with hematoxylin and eosin staining and modified Gmelin's stain for bile pigments.
  
  
  RESULTS
  The survival time was greater in the rats given the microencapsulated hepatocytes than in the control rats (17.3 +/- 3 vs 3.7 +/- 0.1 hours; P <.01). The blood ammonia concentrations increased soon after total hepatectomy but remained significantly lower in the rats with microencapsulated hepatocytes (P <.05). The microcapsules contained numerous viable hepatocytes with abundant bile pigments and no lymphocytic infiltration.
  
  
  CONCLUSIONS
  Microencapsulated hepatocytes with an ultrathin polymer layer that protects them from inflammatory and lymphocytic reactions may facilitate their ability to function. In this study, 4 x 10(7) hepatocytes significantly prolonged the survival of rats that underwent hepatectomy and supported ammonia metabolism. Further development of this technique may permit its use in patients with hepatic failure.
authors.affiliation: Second Department of Surgery, Hirosaki University School of Medicine, Hirosaki, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Umehara
authors.forename: K
authors.initials: K
authors.lastname: Hakamada
authors.forename: K
authors.initials: K
authors.lastname: Seino
authors.forename: K
authors.initials: K
authors.lastname: Aoki
authors.forename: Y
authors.initials: Y
authors.lastname: Toyoki
authors.forename: M
authors.initials: M
authors.lastname: Sasaki
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000818:Animals; D001769:Blood / Q000378:metabolism; D002214:Capsules; D002470:Cell Survival; D006498:Hepatectomy; D022781:Hepatocytes / Q000473:pathology / Q000637:transplantation*; D008297:Male; D008863:Microspheres; D010537:Peritoneum / Q000473:pathology / Q000601:surgery*; D051381:Rats; D017208:Rats, Wistar; D016019:Survival Analysis; D014180:Transplantation / Q000379:methods
chemical_list: D002214:Capsules; D000641:Ammonia