title: Silencing Porcine CMAH and GGTA1 Genes Significantly Reduces Xenogeneic Consumption of Human Platelets by Porcine Livers.
abstract: BACKGROUND
  A profound thrombocytopenia limits hepatic xenotransplantation in the pig-to-primate model. Porcine livers also have shown the ability to phagocytose human platelets in the absence of immune-mediated injury. Recently, inactivation of the porcine ASGR1 gene has been shown to decrease this phenomenon. Inactivating GGTA1 and CMAH genes has reduced the antibody-mediated barrier to xenotransplantation; herein, we describe the effect that these modifications have on xenogeneic consumption of human platelets in the absence of immune-mediated graft injury.
  
  
  METHODS
  Wild type (WT), ASGR1, GGTA1, and GGTA1CMAH knockout pigs were compared for their xenogeneic hepatic consumption of human platelets. An in vitro assay was established to measure the association of human platelets with liver sinusoidal endothelial cells (LSECs) by immunohistochemistry. Perfusion models were used to measure human platelet uptake in livers from WT, ASGR1, GGTA1, and GGTA1 CMAH pigs.
  
  
  RESULTS
  GGTA1, CMAH LSECs exhibited reduced levels of human platelet binding in vitro when compared with GGTA1 and WT LSECs. In a continuous perfusion model, GGTA1 CMAH livers consumed fewer human platelets than GGTA1 and WT livers. GGTA1 CMAH livers also consumed fewer human platelets than ASGR1 livers in a single-pass model.
  
  
  CONCLUSIONS
  Silencing the porcine carbohydrate genes necessary to avoid antibody-mediated rejection in a pig-to-human model also reduces the xenogeneic consumption of human platelets by the porcine liver. The combination of these genetic modifications may be an effective strategy to limit the thrombocytopenia associated with pig-to-human hepatic xenotransplantation.
authors.affiliation: 1 Department of Surgery, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: James Russell
authors.initials: JR
authors.lastname: Butler
authors.forename: Leela L
authors.initials: LL
authors.lastname: Paris
authors.forename: Ross L
authors.initials: RL
authors.lastname: Blankenship
authors.forename: Richard A
authors.initials: RA
authors.lastname: Sidner
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Martens
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Ladowski
authors.forename: Ping
authors.initials: P
authors.lastname: Li
authors.forename: Jose L
authors.initials: JL
authors.lastname: Estrada
authors.forename: Matthew
authors.initials: M
authors.lastname: Tector
authors.forename: A Joseph
authors.initials: AJ
authors.lastname: Tector
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D000910:Antibodies, Heterophile / Q000276:immunology / Q000378:metabolism; D015478:Antigens, Heterophile / Q000276:immunology / Q000378:metabolism; D037263:Asialoglycoprotein Receptor / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D005700:Galactosyltransferases / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D006084:Graft Rejection / Q000276:immunology / Q000517:prevention & control; D006085:Graft Survival; D064593:Heterografts; D006801:Humans; D008099:Liver / Q000276:immunology / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000172:deficiency / Q000235:genetics* / Q000276:immunology; D010587:Phagocytosis; D010973:Platelet Adhesiveness; D013552:Swine; D013921:Thrombocytopenia / Q000097:blood / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D000910:Antibodies, Heterophile; D015478:Antigens, Heterophile; D037263:Asialoglycoprotein Receptor; D006899:Mixed Function Oxygenases; C074383:CMPacetylneuraminate monooxygenase; D005700:Galactosyltransferases; C530267:alpha-1,3-galactosyltransferase 1, porcine