title: Evaluation of engraftment and immunological tolerance after reduced intensity conditioning in a rhesus hematopoietic stem cell gene therapy model.
abstract: Reduced intensity conditioning (RIC) is desirable for hematopoietic stem cell (HSC) targeted gene therapy; however, RIC may be insufficient for efficient engraftment and inducing immunological tolerance to transgenes. We previously established long-term gene marking in our rhesus macaque autologous HSC transplantation model following 10 Gy total body irradiation (TBI). In this study, we evaluated RIC transplantation with 4 Gy TBI in two rhesus macaques that received equal parts of CD34(+) cells transduced with green fluorescent protein (GFP)-expressing lentiviral vector and empty vector not expressing transgenes. In both animals, equivalently low gene marking between GFP and empty vectors was observed 6 months post-transplantation, even with efficient transduction of CD34(+) cells in vitro. Autologous lymphocyte infusion with GFP marking resulted in an increase of gene marking in lymphocytes in a control animal with GFP tolerance, but not in the two RIC-transplanted animals. In vitro assays revealed strong cellular and humoral immune responses to GFP protein in the two RIC-transplanted animals, but this was not observed in controls. In summary, 4 Gy TBI is insufficient to permit engraftment of genetically modified HSCs and induce immunological tolerance to transgenes. Our findings should help in the design of conditioning regimens in gene therapy trials.
authors.affiliation: Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institutes (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: N
authors.initials: N
authors.lastname: Uchida
authors.affiliation: Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institutes (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: R P
authors.initials: RP
authors.lastname: Weitzel
authors.affiliation: Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institutes (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Evans
authors.affiliation: Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institutes (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: R
authors.initials: R
authors.lastname: Green
authors.affiliation: Hematology Branch, NHLBI, NIH, 5 Research Court, Rockville, MD, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Bonifacino
authors.affiliation: Hematology Branch, NHLBI, NIH, 5 Research Court, Rockville, MD, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Krouse
authors.affiliation: Hematology Branch, NHLBI, NIH, 5 Research Court, Rockville, MD, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Metzger
authors.affiliation: Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institutes (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Hsieh
authors.affiliation: Hematology Branch, NHLBI, NIH, 5 Research Court, Rockville, MD, USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Donahue
authors.affiliation: Molecular and Clinical Hematology Branch, National Heart Lung and Blood Institutes (NHLBI)/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institutes of Health (NIH), Bethesda, MD, USA.
authors.forename: J F
authors.initials: JF
authors.lastname: Tisdale
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism*; D002478:Cells, Cultured; D003131:Combined Modality Therapy; D004307:Dose-Response Relationship, Radiation; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage*; D006085:Graft Survival / Q000276:immunology* / Q000528:radiation effects*; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000276:immunology* / Q000528:radiation effects; D016086:Lentivirus / Q000235:genetics; D008253:Macaca mulatta; D023421:Models, Animal; D014161:Transduction, Genetic; D019076:Transgenes; D019172:Transplantation Conditioning; D014916:Whole-Body Irradiation / Q000379:methods*
chemical_list: D018952:Antigens, CD34