title: Enhancing Survival of Human Hepatocytes by Neonatal Thymectomy and Partial Hepatectomy in Micro-miniature Pigs.
abstract: BACKGROUND
  With the goal of in vivo cultivation of human hepatocytes that have not been sufficient in full differentiation in vitro, the advantage of neonatal thymectomy was verified on expansion of xenogeneic human hepatocyte in the micro-miniature pig (MMP).
  
  
  METHODS
  The thymus was excised immediately after the birth of the MMPs via cesarean section. Newborns were fed by artificial feeding under specific pathogen-free conditions. The thymectomized and nonthymectomized littermates were transplanted with human hepatocytes via a portal vein with or without partial hepatectomy at the MMP adult stage.
  
  
  RESULTS
  The growth of thymectomized MMPs and the sham operated littermates was not significantly different; the former weighed 1.98 ± 0.30 kg (average ± standard deviation, n = 4) and the latter weighed 2.28 ± 0.39 kg (n = 4) at 1 month of age, and 17.48 ± 1.92 kg and 16.75 ± 2.68 kg at 12 months of age. Blood thymosin α1concentrations in the thymectomy group were significantly lower than in the control group (0.22 ± 0.05 ng/mL vs 0.46 ± 0.16 ng/mL; n = 4, 12 months old, P = .029). After human hepatocyte transplantation, human albumin levels were detectable on day 28 in the peripheral blood of the thymectomy plus hepatectomy group (14.3 ± 4.9 ng/mL [± range, n = 2]) but were not detectable even on day 21 in the control group.
  
  
  CONCLUSIONS
  Neonatal thymectomy was successfully achieved in infantile MMPs born via cesarean section. These pigs were considered to be an ideal in vivo bioreactor for human hepatocytes.
authors.affiliation: Department of Organ Fabrication, Keio University School of Medicine, Tokyo, Japan; Division of Advanced Medical Sciences, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: H C
authors.initials: HC
authors.lastname: Hsu
authors.affiliation: Department of Organ Fabrication, Keio University School of Medicine, Tokyo, Japan; Division of Advanced Medical Sciences, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Enosawa
authors.affiliation: Division of Advanced Medical Sciences, National Center for Child Health and Development, Tokyo, Japan; Kohno Clinical Medicine Research Institute, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamazaki
authors.affiliation: Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tohyama
authors.affiliation: Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Fujita
authors.affiliation: Department of Cardiology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Fukuda
authors.affiliation: Department of Organ Fabrication, Keio University School of Medicine, Tokyo, Japan. Electronic address: organfabri@keio.jp.
authors.forename: E
authors.initials: E
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D005260:Female; D006498:Hepatectomy; D022781:Hepatocytes / Q000166:cytology*; D064593:Heterografts; D006801:Humans; D023421:Models, Animal; D013552:Swine; D013556:Swine, Miniature; D013934:Thymectomy