Submitted March 23, 2005
Accepted October 28, 2005
Tolerance induction by lentiviral gene therapy with a non-myeloablative regimen
Noboru Mitsuhashi, Jacqueline Fischer-Lougheed, Irina Shulkin, Annette Kleihauer, Donald B Kohn, Kenneth I Weinberg, Vaughn A Starnes, and Mary Kearns-Jonker*
Division of Cardiothoracic Surgery, Departments of Cardiothoracic Surgery, Transplantation Biology Research Laboratory, Childrens Hospital Los Angeles and Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
Division of Research Immunology and Bone Marrow Transplantation, Department of Pediatrics, Molecular Microbiology and Immunology, Childrens Hospital Los Angeles and Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
* Corresponding author; email: mkearns{at}chla.usc.edu.
Antibodies (Abs) directed at the Gal
1,3Gal
1,4GlcNAc-R (Gal) carbohydrate epitope initiate xenograft rejection. Previously, we have shown that bone marrow transplantation (BMT) with lentivirus-mediated gene transfer of porcine 1,3galactosyltransferase (GalT) is able to induce tolerance to Gal expressing heart grafts following a lethal dose of irradiation. Here we show the first demonstration of permanent survival of Gal+ hearts following transplantation with autologous, lentivirus-transduced BM using a non-myeloablative regimen. Autologous BM from GalT knockout (GalT-/-) mice was transduced with a lentiviral vector expressing porcine GalT and transplanted into sublethally-irradiated (3Gy) GalT-/- mice. Chimerism in the peripheral blood cells (PBCs) remained low, but was higher in the BM, especially within the stromal cell population. Mice reconstituted with GalT did not produce anti-Gal Abs over time. We immunized these mice with Gal expressing cells and assessed humoral immune responses. Anti-Gal xenoantibodies were not produced in mice reconstituted with GalT, but normal Ab responses to other xenoantigens were detected. Mice reconstituted with GalT accepted Gal+ heart grafts over 100 days. Transduction with lentiviral vectors results in chimerism at levels sufficient to induce long-term tolerance under non-myeloablative conditions.
