title: Prolonged survival of pig islets xenograft by adenovirus-mediated expression of either the membrane-bound human FasL or the human decoy Fas antigen gene.
abstract: BACKGROUND
  Pig islets are considered an attractive alternative treatment for patients with Type 1 diabetes. However, pig islet xenografts, transplanted into non-human primates, are directly rejected by cell-mediated processes. We have previously reported that cell-mediated xenograft-rejections, and especially human CD8(+) cytotoxic T lymphocytes (CTL)-mediated cytotoxicity, are highly detrimental to pig xenograft cells. Moreover, we have explored novel strategies for the prevention of CTL killing by overexpression of either human decoy Fas antigen or membrane-bound human FasL in pig endothelial cells. In this study, we assessed the cytoprotective effects of these molecules for pig islets both in vitro and in vivo.
  
  
  METHODS
  Pig islets were freshly isolated by modified Ricordi's methods. Subsequently, these islets were transfected with an adenoviral expression vector containing the DNA fragments of either membrane-bound human FasL or human decoy Fas. Transfected islets were transplanted into preimmunized diabetic rats under the kidney capsule. Control pig islets (i.e., MOCK), which were transfected with an adenoviral expression vector containing only the enhanced green fluorescent protein gene, were also transplanted.
  
  
  RESULTS
  Efficiency of adenoviral expressions of these molecules in pig islets was approximately 80% at a multiplicity of infection of 100. In an in vitro assay, approximately 80% suppression of cytotoxicity was observed in membrane-bound human FasL-expressing pig islets and 60% inhibition of CTL killing was displayed in decoy Fas expression pig islets. In an in vivo transplant model, prolonged survival of pig islets xenografts, expressing either membrane-bound human FasL or human decoy Fas genes, was elicited in comparison with that of control islets xenografts.
  
  
  CONCLUSIONS
  The extracellular remodeling of either death receptor or death ligand genes by adenoviral expression was effective for the prevention of CTL-mediated xenocytotoxicity in pig islets.
authors.affiliation: Department of Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Kawamoto
authors.forename: Masahiro
authors.initials: M
authors.lastname: Tanemura
authors.forename: Toshinori
authors.initials: T
authors.lastname: Ito
authors.forename: Takashi
authors.initials: T
authors.lastname: Deguchi
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Machida
authors.forename: Toshirou
authors.initials: T
authors.lastname: Nishida
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Doki
authors.forename: Masaki
authors.initials: M
authors.lastname: Mori
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Sawa
mesh_terms: D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D053222:Fas Ligand Protein / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005822:Genetic Vectors / Q000235:genetics; D006085:Graft Survival / Q000276:immunology*; D006801:Humans; D007515:Islets of Langerhans / Q000166:cytology / Q000276:immunology; D016381:Islets of Langerhans Transplantation; D011485:Protein Binding; D051381:Rats; D013552:Swine / Q000276:immunology / Q000601:surgery; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D013997:Time Factors; D014183:Transplantation, Heterologous / Q000276:immunology; D019014:fas Receptor / Q000235:genetics / Q000378:metabolism*
chemical_list: D053222:Fas Ligand Protein; D019014:fas Receptor