title: Transplantation of hepatocytes from genetically engineered pigs into baboons.
abstract: Some patients with acute or acute-on-chronic hepatic failure die before a suitable human liver allograft becomes available. Encouraging results have been achieved in such patients by the transplantation of human hepatocyte progenitor cells from fetal liver tissue. The aim of the study was to explore survival of hepatocytes from genetically engineered pigs after direct injection into the spleen and other selected sites in immunosuppressed baboons to monitor the immune response and the metabolic function and survival of the transplanted hepatocytes.
  
  
  
  Baboons (n=3) were recipients of GTKO/hCD46 pig hepatocytes. All three baboons received anti-thymocyte globulin (ATG) induction and tapering methylprednisolone. Baboon 1 received maintenance immunosuppressive therapy with tacrolimus and rapamycin. Baboons 2 and 3 received an anti-CD40mAb/rapamycin-based regimen that prevents sensitization to pig solid organ grafts. The baboons were euthanized 4 or 5 weeks after hepatocyte transplantation. The baboon immune response was monitored by the measurement of anti-non-Gal IgM and IgG antibodies (by flow cytometry) and CFSE-mixed lymphocyte reaction. Monitoring for hepatocyte survival and function was by (i) real-time PCR detection of porcine DNA, (ii) real-time PCR for porcine gene expression, and (iii) pig serum albumin levels (by ELISA). The sites of hepatocyte injection were examined microscopically.
  
  
  
  Detection of porcine DNA and porcine gene expression was minimal at all sites of hepatocyte injection. Serum levels of porcine albumen were very low-500-1000-fold lower than in baboons with orthotopic pig liver grafts, and approximately 5000-fold lower than in healthy pigs. No hepatocytes or infiltrating immune cells were seen at any of the injection sites. Two baboons (Baboons 1 and 3) demonstrated a significant increase in anti-pig IgM and an even greater increase in IgG, indicating sensitization to pig antigens.
  
  
  
  As a result of this disappointing experience, the following points need to be considered. (i) Were the isolated pig hepatocytes functionally viable? (ii) Are pig hepatocytes more immunogenic than pig hearts, kidneys, artery patch grafts, or islets? (iii) Does injection of pig cells (antigens) into the spleen and/or lymph nodes stimulate a greater immune response than when pig tissues are grafted at other sites? (iv) Did the presence of the recipient's intact liver prevent survival and proliferation of pig hepatocytes? (v) Is pig CD47-primate SIRP-α compatibility essential? In conclusion, the transplantation of genetically engineered pig hepatocytes into multiple sites in immunosuppressed baboons was associated with very early graft failure. Considerable further study is required before clinical trials should be undertaken.
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Hayato
authors.initials: H
authors.lastname: Iwase
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.|Department of General Surgery, First Hospital of Shanxi Medical University, Taiyuan, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Surgery, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Eva
authors.initials: E
authors.lastname: Schmelzer
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ezzelarab
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Martin
authors.initials: M
authors.lastname: Wijkstrom
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Hara
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Whayoung
authors.initials: W
authors.lastname: Lee
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Jagjit
authors.initials: J
authors.lastname: Singh
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Long
authors.affiliation: Department of Pathology, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Lagasse
authors.affiliation: Department of Surgery, University of Pittsburgh, Pittsburgh, PA, USA.|Department of Bioengineering, McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Jörg C
authors.initials: JC
authors.lastname: Gerlach
authors.affiliation: Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: David K C
authors.identifier: 0000-0002-8899-9431
authors.initials: DKC
authors.lastname: Cooper
authors.affiliation: Mediterranean Institute for Transplantation and Advanced Specialized Therapies (ISMETT), Palermo, Italy.
authors.forename: Bruno
authors.initials: B
authors.lastname: Gridelli
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D000906:Antibodies / Q000276:immunology; D000917:Antibody Formation / Q000235:genetics / Q000276:immunology; D000941:Antigens / Q000276:immunology; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology*; D022781:Hepatocytes / Q000276:immunology* / Q000637:transplantation; D007165:Immunosuppression Therapy / Q000379:methods; D007166:Immunosuppressive Agents / Q000494:pharmacology; D048529:Papio hamadryas / Q000276:immunology; D013552:Swine; D014183:Transplantation, Heterologous / Q000379:methods
chemical_list: D000906:Antibodies; D000941:Antigens; D007166:Immunosuppressive Agents
keywords: baboon; hepatocytes; pig; xenotransplantation