title: The development of humanized liver with Rag1 knockout rats.
abstract: BACKGROUND
  The animal model with humanized liver is useful for testing drug metabolism and toxicity in preclinical studies. A mouse model has been reported in which the liver was repopulated more than 90% with human hepatocytes; however, in the rat, the target is far from being reached. In this study, we attempt to develop a humanized liver model with an immunodeficient rat.
  
  
  METHODS
  Rag1 knockout rats were treated with neonatal thymectomy. At 3 and 4 weeks of age, they were injected with hepatotoxin retrorsine; 2 weeks after, the animals were subjected to 70% partial hepatectomy and transplanted with immature human hepatocytes via portal vein. The recipients were also treated with anti-asialo GM1 antibody weekly from the day before transplantation and were injected with FK506 every 3 days after transplantation.
  
  
  RESULTS
  In Rag1 knockout rats, B lymphocytes were deleted almost completely in peripheral blood. However, T and natural killer (NK) lymphocytes were kept present. When they were treated additionally with neonatal thymectomy for T-lymphocyte deletion and suppressed neutralized NK lymphocytes with anti-asialo GM1, B, T, and NK cells in lymphocytes were reduced to very low levels of 0.75%, 1.58%, and 0.26%, respectively. After transplanting human donor hepatocytes into retrorsine-treated recipient livers, at week 3 the human cell-derived hepatic colonies were expanded in the recipient liver and the liver repopulation rate with human hepatocytes reached approximately 17%. The human hepatocyte-specific genes, albumin, CYP3A4, CYP2C18, and CYP2C9, also could be detected in the recipient rat.
  
  
  CONCLUSIONS
  It is possible to generate a chimera animal with humanized liver in a novel severely immunodeficient rat model.
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tsuchida
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan. Electronic address: ywzheng@yokohama-cu.ac.jp.
authors.forename: Y-W
authors.initials: YW
authors.lastname: Zheng
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan.
authors.forename: R-R
authors.initials: RR
authors.lastname: Zhang
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Takebe
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Ueno
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Sekine
authors.affiliation: Department of Regenerative Medicine, Graduate School of Medicine, Yokohama City University, Yokohama, Kanagawa, Japan. Electronic address: rtanigu@med.yokohama-cu.ac.jp.
authors.forename: H
authors.initials: H
authors.lastname: Taniguchi
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics / Q000378:metabolism; D001402:B-Lymphocytes / Q000276:immunology; D049109:Cell Proliferation; D065729:Cytochrome P-450 CYP2C9 / Q000235:genetics / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism; D005677:G(M1) Ganglioside / Q000276:immunology; D016654:Genes, RAG-1; D005819:Genetic Markers; D006498:Hepatectomy; D022781:Hepatocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000637:transplantation*; D006801:Humans; D016867:Immunocompromised Host; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008099:Liver / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000601:surgery*; D008115:Liver Regeneration; D016031:Liver Transplantation / Q000379:methods*; D023421:Models, Animal; D011763:Pyrrolizidine Alkaloids / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D055647:Rats, Transgenic; D012709:Serum Albumin / Q000235:genetics / Q000378:metabolism; D000075462:Serum Albumin, Human; D013045:Species Specificity; D013601:T-Lymphocytes / Q000276:immunology; D016559:Tacrolimus / Q000494:pharmacology; D013934:Thymectomy; D013997:Time Factors; D018183:Transplantation Chimera
chemical_list: C422455:ALB protein, human; D000906:Antibodies; D005819:Genetic Markers; D007166:Immunosuppressive Agents; D011763:Pyrrolizidine Alkaloids; D012333:RNA, Messenger; D012709:Serum Albumin; D005677:G(M1) Ganglioside; C018835:asialo GM1 ganglioside; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C082185:CYP2C18 protein, human; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D016559:Tacrolimus; C003300:retrorsine; D000075462:Serum Albumin, Human