A novel approach to xenotransplantation combining surface engineering and genetic modification of isolated adult porcine islets.

Academic Article

Abstract

  • BACKGROUND: Effective cytoprotection to xenoislets would circumvent the major tissue limitation for pancreatic islet transplantation (PIT). Cell-surface engineering with poly[ethylene glycol] (PEG) derivatives can successfully prevent antibody binding to the surface antigens. Gene transfer of the antiapoptotic Bcl-2 gene has been shown to decrease cytotoxicity mediated by xenoreactive natural antibodies and complement. In this study, we assessed survival and function of surface-engineered porcine islets genetically modified to overexpress Bcl-2. METHODS: Incorporation of PEG derivatives into the islet surface and adenovirus-mediated gene transfer of Bcl-2 (AdBcl-2) was accomplished within 24 hours post-isolation. Cytotoxicity induced by human xenoreactive natural antibodies was evaluated by islet intracellular lactate dehydrogenase release and microscopic analysis using membrane-integrity staining. Islet functionality was assessed by static incubation and after intraportal infusion (5000 IEQ) into diabetic NOD-SCID mice reconstituted with human lymphocytes (5 x 10 8 /intraperitoneally/15 days before PIT). RESULTS: No significant change in islet viability, morphology, and functionality was demonstrated after the incorporation of PEG-mono-succimidyl-succinate (MSPEG), or PEG-di-succimidyl-succinate "end"-capped with albumin (DSPEG) with or without gene transfer of Bcl-2. Islets treated with MSPEG presented a significant reduction in lactate dehydrogenase release compared with controls (41.2 +/- 3 vs 72.1 +/- 7, respectively, P <.05). Further protection was accomplished by DSPEG or AdBcl-2. The maximal cytoprotection was achieved by DSPEG +AdBcl-2 (15.5 +/- 4.9%, P <.001). Nonfasting glucose >200 mg/dL was found in 100% of the animals given control islets (n = 6) within 48 hours post-transplant. In contrast, euglycemia was achieved in 100% of the animals given islets modified with DSPEG + AdBcl-2 during the observation time. CONCLUSIONS: Surface-engineering with functionalized PEG derivatives in combination with genetic modification with Bcl-2 significantly reduced islet loss after PIT. Application of this novel technology may improve results in xenoislet transplantation.
  • Published In

  • Surgery  Journal
  • Keywords

  • Animals, Apoptosis, Cell Survival, Cells, Cultured, Gene Expression, Gene Transfer Techniques, Genes, bcl-2, Islets of Langerhans, Islets of Langerhans Transplantation, Models, Animal, Polyethylene Glycols, Surface-Active Agents, Swine, Transplantation, Heterologous
  • Digital Object Identifier (doi)

    Authorlist

  • Contreras JL; Xie D; Mays J; Smyth CA; Eckstein C; Rahemtulla FG; Young CJ; Anthony Thompson J; Bilbao G; Curiel DT
  • Start Page

  • 537
  • End Page

  • 547
  • Volume

  • 136
  • Issue

  • 3